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Objectives: Hypothesis tests for hearing threshold data may be challenging due to the special structure of the response variable, which consists of the measurements from the participant's two ears at multiple frequencies. The commonly-used methods may have inflated type I error rates for the global test that examines whether exposure-hearing threshold associations exist in at least one of the frequencies. We propose using both-ear methods, including all frequencies in the same model for hypothesis testing., Design: We compared the both-ear method to commonly used single-ear methods, such as the worse-ear, better-ear, left/right-ear, average-ear methods, and both-ear methods that evaluate individual audiometric frequencies in separate models, through both theoretical consideration and a simulation study. Differences between the methods were illustrated using hypothesis tests for the associations between the Dietary Approaches to Stop Hypertension adherence score and 3-year change in hearing thresholds among participants in the Conservation of Hearing Study., Results: We found that (1) in the absence of ear-level confounders, the better-ear, worse-ear and left/right-ear methods have less power for frequency-specific tests and for the global test; (2) in the presence of ear-level confounders, the better-ear and worse-ear methods are invalid, and the left/right-ear and average-ear methods have less power, with the power loss in the left/right-ear much greater than the average-ear method, for frequency-specific tests and for the global test; and (3) the both-ear method with separate analyses for individual frequencies is invalid for the global test., Conclusions: For hypothesis testing to evaluate whether there are significant associations between an exposure of interest and audiometric hearing threshold measurements, the both-ear method that includes all frequencies in the same model is the recommended analytic approach., (Copyright © 2024 The Authors. Ear & Hearing is published on behalf of the American Auditory Society, by Wolters Kluwer Health, Inc.)

Objectives: Audiometric testing typically does not include frequencies above 8 kHz. However, recent research suggests that extended high-frequency (EHF) sensitivity could affect hearing in natural communication environments. Clinical assessment of hearing often employs pure tones and frequency-modulated (FM) tones interchangeably regardless of frequency. The present study was designed to evaluate how the stimulus chosen to measure EHF thresholds affects estimates of hearing sensitivity., Design: The first experiment used standard audiometric procedures to measure 8- and 16-kHz thresholds for 5- to 28-year olds with normal hearing in the standard audiometric range (250 to 8000 Hz). Stimuli were steady tones, pulsed tones, and FM tones. The second experiment tested 18- to 28-year olds with normal hearing in the standard audiometric range using psychophysical procedures to evaluate how changes in sensitivity as a function of frequency affect detection of stimuli that differ with respect to bandwidth, including bands of noise. Thresholds were measured using steady tones, pulsed tones, FM tones, narrow bands of noise, and one-third-octave bands of noise at a range of center frequencies in one ear., Results: In experiment 1, thresholds improved with increasing age at 8 kHz and worsened with increasing age at 16 kHz. Thresholds for individual participants were relatively similar for steady, pulsed, and FM tones at 8 kHz. At 16 kHz, mean thresholds were approximately 5 dB lower for FM tones than for steady or pulsed tones. This stimulus effect did not differ as a function of age. Experiment 2 replicated this greater stimulus effect at 16 kHz than at 8 kHz and showed that the slope of the audibility curve accounted for these effects., Conclusions: Contrary to prior expectations, there was no evidence that the choice of stimulus type affected school-age children more than adults. For individual participants, audiometric thresholds at 16 kHz were as much as 20 dB lower for FM tones than for steady tones. Threshold differences across stimuli at 16 kHz were predicted by differences in audibility across frequency, which can vary markedly between listeners. These results highlight the importance of considering spectral width of the stimulus used to evaluate EHF thresholds., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Objectives: Current evidence supports the growing application of extended high-frequency (EHF: 9 to 20 kHz) audiometry in hearing research, which likely results from the high vulnerability of this frequency region to damage induced by known auditory risk factors. The present systematic review and meta-analysis were performed to investigate whether adults with a normal audiogram and tinnitus show increased EHF hearing thresholds relative to control peers., Design: A comprehensive search was undertaken on electronic databases consisting of PubMed, ScienceDirect, Wiley, and Google Scholar using combined keywords: "tinnitus," "extended high frequency," "normal audiogram," and "hidden hearing loss.", Results: From 261 articles found by searching databases, nine studies met the inclusion criteria for the meta-analysis. A significant difference was observed between tinnitus and control groups in the effect size analysis of hearing thresholds at 10, 12.5, 14, 16, and 18 kHz ( p ≤ 0.001), and the I-square heterogeneity analysis was below 50% in all studies ( p ≥ 0.131). Visual inspection by the Funnel plot and Egger's regression test ( p ≥ 0.211) also exhibited no publication bias in the meta-analyses., Conclusions: Our findings are in support of the idea that in most cases, tinnitus is associated with some degree of cochlear mechanical dysfunction, which may not be detected by conventional audiometry alone. This finding underscores the significance of EHF audiometry in clinical practice, which may help both early identification of individuals susceptible to developing tinnitus and reduce the number of new cases through preventive counseling programs., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Objectives: The first objective of this study was to compare the predicted audiometric thresholds obtained by auditory steady state response (ASSR) and auditory brainstem response (ABR) in infants and toddlers when both techniques use optimal stimuli and detection algorithms. This information will aid in determining the basis for large discrepancies in ABR and ASSR measures found in past studies. The hypothesis was that advancements in ASSR response detection would improve (lower) thresholds and decrease discrepancies between the thresholds produced by the two techniques. The second objective was to determine and compare test times required by the two techniques to predict thresholds for both ears at the 4 basic audiometric frequencies of 500, 1000, 2000, and 4000 Hz., Design: A multicenter clinical study was implemented at three university-based children's hospital audiology departments. Participants were 102 infants and toddlers referred to the centers for electrophysiologic testing for audiometric purposes. The test battery included wideband tympanometry, distortion-product otoacoustic emissions, and threshold measurements at four frequencies in both ears using ABR and ASSR (randomized) as implemented on the Interacoustics Eclipse systems with "Next-Generation" ASSR detection and FMP analysis for ABR. Both methods utilized narrow band CE-Chirp stimuli. Testers were trained on a specialized test battery designed to minimize test time for both techniques. Testing with both techniques was performed in one session. Thresholds were evaluated and confirmed by the first author and correction factors were applied. Test times were documented in system software., Results: Corrected thresholds for ABR and ASSR were compared by regression, by the Bland-Altman technique and by matched pairs t tests. Thresholds were significantly lower for ASSR than ABR. The ABR-ASSR discrepancy at 500 Hz was 14.39 dB, at 1000 Hz was 10.12 dB, at 2000 Hz was 3.73 dB, and at 4000 Hz was 3.67 dB. The average test time for ASSR of 19.93 min (for 8 thresholds) was found to be significantly lower (p < 0.001) than the ABR test time of 32.15 min. One half of the subjects were found to have normal hearing. ASSR thresholds plotted in dB nHL for normal-hearing children in this study were found to be the lowest yet described except for one study which used the same technology., Conclusions: This study found a reversal of previous findings with up to 14 dB lower thresholds found when using the ASSR technique with "Next-Generation" detection as compared with ABR using an automated detection (FMP). The test time for an audiogram prediction was significantly lower when using ASSR than ABR but was excellent by clinical standards for both techniques. ASSRs improved threshold performance was attributed to advancements in response detection including utilization of information at multiple harmonics of the modulation frequency. The stimulation paradigm which utilized narrow band CE-Chirps also contributed to the low absolute levels of the thresholds in nHL found with both techniques.

Objectives: The purpose of this study was to describe normal characteristics of distortion product otoacoustic emission (DPOAE) signal and noise level in a group of newborns and infants with normal hearing followed longitudinally from birth to 15 months of age., Design: This is a prospective, longitudinal study of 231 infants who passed newborn hearing screening and were verified to have normal hearing. Infants were enrolled from a well-baby nursery and two neonatal intensive care units (NICUs) in Cincinnati, OH. Normal hearing was confirmed with threshold auditory brainstem response and visual reinforcement audiometry. DPOAEs were measured in up to four study visits over the first year after birth. Stimulus frequencies f1 and f2 were used with f2/f1 = 1.22, and the DPOAE was recorded at frequency 2f1-f2. A longitudinal repeated-measure linear mixed model design was used to study changes in DPOAE level and noise level as related to age, middle ear transfer, race, and NICU history., Results: Significant changes in the DPOAE and noise levels occurred from birth to 12 months of age. DPOAE levels were the highest at 1 month of age. The largest decrease in DPOAE level occurred between 1 and 5 months of age in the mid to high frequencies (2 to 8 kHz) with minimal changes occurring between 6, 9, and 12 months of age. The decrease in DPOAE level was significantly related to a decrease in wideband absorbance at the same f2 frequencies. DPOAE noise level increased only slightly with age over the first year with the highest noise levels in the 12-month-old age range. Minor, nonsystematic effects for NICU history, race, and gestational age at birth were found, thus these results were generalizable to commonly seen clinical populations., Conclusions: DPOAE levels were related to wideband middle ear absorbance changes in this large sample of infants confirmed to have normal hearing at auditory brainstem response and visual reinforcement audiometry testing. This normative database can be used to evaluate clinical results from birth to 1 year of age. The distributions of DPOAE level and signal to noise ratio data reported herein across frequency and age in normal-hearing infants who were healthy or had NICU histories may be helpful to detect the presence of hearing loss in infants.

Objectives: Hearing loss from ototoxicity is often most pronounced at high frequencies. To improve patient monitoring and compliance, high-frequency testing methods should be short and easy to administer. We evaluated the repeatability and accuracy of a Békésy-like, fixed-level frequency threshold (FLFT) technique. This test takes less than a minute and could provide a rapid and effective way to determine the highest audible frequency. We hypothesized the FLFT test would be repeatable in normal-hearing subjects, and accurate when compared with Békésy fixed-frequency audiometry in the sensitive region for ototoxicity (SRO)., Design: Twenty-nine normal-hearing subjects (20 females, 9 males) performed 2 different automated audiometry tests at least 4 times over a period of no less than 3 weeks. Ages ranged from 23 to 35 years (average = 28 years). Subjects completed testing under Sennheiser HDA-200 headsets. Initial fixed-frequency audiometry thresholds were obtained at frequencies ranging from 0.5 to 20 kHz to identify each subject's highest audible frequency, which was used to determine the SRO. The SRO was defined as the seven frequencies at and below the highest audible frequency in 1/6-octave steps. These frequencies were monitored with fixed-frequency audiometry. At each session, the FLFT test was administered at 80 dB SPL. Subjects used a Békésy-style tracking method to determine the frequency threshold. All testing was completed in a sound booth (single wall, Industrial Acoustics Company) using a computerized, laptop-based, system. FLFT repeatability was calculated as the root mean square difference from the first test session. FLFT accuracy was calculated as the difference from the highest audible frequency determined from fixed-frequency audiometry interpolated to 80 dB SPL level., Results: The FLFT average RMSD for intersession variability was 0.05 ± 0.05 octaves. The test showed no learning effect [F(3,78) = 0.7; p = 0.6]. The overall intersession variability for SRO fixed-frequency audiometry thresholds at all frequencies was within clinically acceptable test-retest variability (10 dB) at 5.8 dB (range 2.7 to 9.9 dB). The SRO fixed-frequency audiometry therefore served as a repeatable basis of comparison for accuracy of the FLFT test. The mean absolute difference between the fixed-frequency audiometry and FLFT-determined highest audible frequency was 0.03 octaves. The FLFT and the highest audible frequency via fixed-frequency audiometry at 80 dB SPL were not different statistically (p = 0.12). The FLFT took approximately 30 seconds to complete, compared with approximately 4.5 min for fixed-frequency audiometry SRO and 20 to 25 min for a traditional ototoxic audiometric assessment., Conclusions: The Békésy-style FLFT was repeatable within 1/12 octave (1 step size in the testing procedure). The FLFT agreed well with the highest audible frequency determined via fixed-frequency audiometry at 80 dB SPL. The FLFT test is amenable to automatic and self-administration and may enable quick, accurate, noise-tolerant ototoxicity, and high-frequency hearing monitoring.

Objectives: Currently available behavioral tools for the assessment of noise-induced hearing loss (NIHL) depend on the reliable cooperation of the subject. Furthermore, in workers' compensation cases, there is considerable financial gain to be had from exaggerating symptoms, such that accurate assessment of true hearing threshold levels is essential. An alternative objective physiologic tool for assessing NIHL is the auditory steady state response (ASSR) test, which combines frequency specificity with a high level of auditory stimulation, making it applicable for the evaluation of subjects with a moderate to severe deficit. The primary aim of the study was to assess the value of the multifrequency ASSR test in predicting the behavioral warble-tone audiogram in a large sample of young subjects with NIHL of varying severity or with normal hearing. The secondary goal was to assess suprathreshold ASSR growth functions in these two groups., Design: The study group included 157 subjects regularly exposed to high levels of occupational noise, who attended a university-associated audiological clinic for evaluation of NIHL from 2009 through 2011. All underwent a behavioral audiogram, and on the basis of the findings, were divided into those with NIHL (108 subjects, 216 ears) or normal hearing (49 subjects, 98 ears). The accuracy of the ASSR threshold estimations for frequencies of 500, 1000, 2000, and 4000 Hz was compared between groups, and the specificity and sensitivity of the ASSR test in differentiating ears with or without NIHL was calculated using receiver operating characteristic analysis. Linear regression analysis was used to formulate an equation to predict the behavioral warble-tone audiogram at each test frequency using ASSR thresholds. Multifrequency ASSR amplitude growth as a function of stimulus intensity was compared between the NIHL and normal-hearing groups for 1000 Hz and 4000 Hz carrier frequencies., Results: In the subjects with NIHL, ASSR thresholds to various frequencies were significantly and highly correlated with the behavioral warble-tone thresholds; Pearson correlation coefficients ranged from 0.6 to 0.8 over the four frequencies tested. Differences between thresholds ranged from 10 to 13 dB. The configuration of the ASSR waveforms closely approximated the behavioral audiogram. The sensitivity for screening hearing thresholds was 92%; by frequency, sensitivity ranged between 92.7 and 98.4%, but specificity was lower, especially at the low frequencies. ASSR accurately predicted moderate and severe NIHL. The mean ASSR growth amplitude to increasing stimulus level for 1000 and 4000 Hz was significantly steeper in the NIHL than in the normal-hearing group, with no significant difference between frequencies., Conclusions: The ASSR test has a high sensitivity to detect moderate to severe hearing loss in subjects with NIHL. Its use can facilitate the early identification of noise-exposed workers with NIHL. It may also serve an important medico-legal function in cases of workers' compensation. The ASSR test is not, by itself, an appropriate tool for hearing screening in the general population.

Objectives: Assessment of auditory and vestibular function in Wolfram Syndrome (WS) patients, using a standardized protocol., Design: Prospective cohort study of 11 patients using otoscopic inspection, tympanometry, otoacoustic emissions, pure tones, speech in noise (SIN), the Speech Intelligibility Index, and rotational chair testing., Results: Mean SNHL diagnosis was 7.3 years with 55% prevalence. Four patients with a Speech Intelligibility Index less than 0.75 (better ear) routinely used bilateral amplification devices. Two patients with normal-hearing sensitivity exhibited abnormal SIN scores. The only patient with significant vestibular dysfunction also had a distinctive low-frequency component to her SNHL., Conclusions: Hearing loss may occur earlier than previously suspected, and comprehensive testing including SIN testing may reveal deficits not apparent with pure-tone testing. Particular configurations of hearing loss may indicate a need for comprehensive vestibular assessment. Because SNHL can be the first symptom of WS, audiologists and otolaryngologists should be vigilant about referring patients with hearing loss for ophthalmologic examination.

Objectives: Audiologists regularly use serial monitoring to evaluate changes in a patient's auditory function over time. Observed changes are compared with reference standards to determine whether further clinical action is necessary. Reference standards are established in a control sample of otherwise healthy subjects to identify the range of auditory shifts that one might reasonably expect to occur in the absence of any pathological insult. Statistical approaches to this seemingly mundane problem typically invoke 1 of 3 approaches: percentiles of the cumulative distribution, the variance of observed shifts, and the "standard error of measurement." In this article, the authors describe the statistical foundation for these approaches, along with a mixed model-based alternative, and identify several necessary, although typically unacknowledged assumptions. Regression to the mean, the phenomenon of an unusual measurement typically followed by a more common one, can seriously bias observed changes in auditory function and clinical expectations. An approach that adjusts for this important effect is also described., Design: Distortion product otoacoustic emissions (DPOAEs) elicited at a single primary frequency, f2 of 3175 Hz, were collected from 32 healthy subjects at baseline and 19 to 29 days later. Ninety percent test-retest reference limits were computed from these data using each statistical approach. DPOAE shifts were also collected from a sample of 18 cisplatin patients tested after 120 to 200 mg of cisplatin. Reference limits established according to each of the statistical approaches in the healthy sample were used to identify clinically alarming DPOAE shifts in the cisplatin patient sample., Results: Reference limits established with any of the parametric methods were similar. The percentile-based approach gave the widest and least precisely estimated intervals. The highest sensitivity for detecting clinically alarming DPOAE shifts was based on a mixed model approach that adjusts for regression to the mean., Conclusions: Parametric methods give similar serial monitoring criteria as long as certain critical assumptions are met by the data. The most flexible method for estimating test-retest limits is based on the linear mixed model. Clinical sensitivity may be further enhanced by adjusting for regression to the mean.

Objective: A great deal of variability exists in the speech-recognition abilities of postlingually deaf adult cochlear implant (CI) recipients. A number of previous studies have shown that duration of deafness is a primary factor affecting CI outcomes; however, there is little agreement regarding other factors that may affect performance. The objective of the present study was to determine the source of variability in CI outcomes by examining three main factors, biographic/audiologic information, electrode position within the cochlea, and cognitive abilities in a group of newly implanted CI recipients., Design: Participants were 114 postlingually deaf adults with either the Cochlear or Advanced Bionics CI systems. Biographic/audiologic information, aided sentence-recognition scores, a high resolution temporal bone CT scan and cognitive measures were obtained before implantation. Monosyllabic word recognition scores were obtained during numerous test intervals from 2 weeks to 2 years after initial activation of the CI. Electrode position within the cochlea was determined by three-dimensional reconstruction of pre- and postimplant CT scans. Participants' word scores over 2 years were fit with a logistic curve to predict word score as a function of time and to highlight 4-word recognition metrics (CNC initial score, CNC final score, rise time to 90% of CNC final score, and CNC difference score)., Results: Participants were divided into six outcome groups based on the percentile ranking of their CNC final score, that is, participants in the bottom 10% were in group 1; those in the top 10% were in group 6. Across outcome groups, significant relationships from low to high performance were identified. Biographic/audiologic factors of age at implantation, duration of hearing loss, duration of hearing aid use, and duration of severe-to-profound hearing loss were significantly and inversely related to performance as were frequency modulated tone, sound-field threshold levels obtained with the CI. That is, the higher-performing outcome groups were younger in age at the time of implantation, had shorter duration of severe-to-profound hearing loss, and had lower CI sound-field threshold levels. Significant inverse relationships across outcome groups were also observed for electrode position, specifically the percentage of electrodes in scala vestibuli as opposed to scala tympani and depth of insertion of the electrode array. In addition, positioning of electrode arrays closer to the modiolar wall was positively correlated with outcome. Cognitive ability was significantly and positively related to outcome; however, age at implantation and cognition were highly correlated. After controlling for age, cognition was no longer a factor affecting outcomes., Conclusion: There are a number of factors that limit CI outcomes. They can act singularly or collectively to restrict an individual's performance and to varying degrees. The highest performing CI recipients are those with the least number of limiting factors. Knowledge of when and how these factors affect performance can favorably influence counseling, device fitting, and rehabilitation for individual patients and can contribute to improved device design and application.

Objective: The aim of this study was to develop a version of the threshold-equalizing noise (TEN) test for the diagnosis of dead regions for use with Etymotic ER-3A insert earphones. The use of such earphones is helpful when testing clients with asymmetric hearing loss or clients whose ear canals tend to collapse under the pressure of supra-aural headphones. It can also be useful when ambient noise levels are problematic., Design: The spectral shape of the noise required to give equal masked thresholds at all frequencies, when expressed in dB HL, was derived by empirical measurements of the electrical output of audiometers using ER-3A earphones. To reduce the loudness of the noise and to minimize distortion generated in the audiometer or earphone, the noise was band-limited between 354 and 6500 Hz. In addition, the noise was synthesized using a method that leads to a low crest factor (ratio of peak to root mean square value). This further reduced audiometer/earphone distortion, and allowed higher levels per ERBN; ERBN is the equivalent rectangular bandwidth of the auditory filter at 1 kHz, as determined using young normally hearing subjects. The test tone frequencies were limited to the range 500 to 4000 Hz. Subjects with normal or near-normal hearing were tested using a noise level of 60 dB HL/ERBN, to assess whether the noise did lead to equal masked thresholds in dB HL for all audiometric frequencies from 500 to 4000 Hz. Thresholds in the TEN were measured using manual audiometry with a 2 dB final step size., Results: The mean-masked thresholds varied by 1.3 dB across frequency when expressed in dB HL, and were close to the noise level per ERBN., Conclusion: This version of the TEN test can be used with ER-3A insert earphones.

Objectives: A number of clinical measures of directivity, including the front-to-back ratio (FBR) and front-to-side ratio (FSR), have been suggested to audiologists to monitor the functionality of hearing aids with directional microphones. These suggestions, however, are based on the assumption that directivity measured clinically changes monotonically when compared with changes measured using the directivity index (DI) and perceptual directional benefit. The objective of the present study was to empirically examine this assumption. In addition, the reliability of the clinical directivity measure was estimated to establish a referral threshold for defective directional microphone hearing aids., Design: The directivity of the directional microphones of two behind-the-ear hearing aids was systematically degraded by plugging the microphone ports. The directivity was measured using four clinical measures: the FBR and FSR performed in the test chamber of a hearing aid analyzer and in sound field. Each measure was repeated four times in each directivity-degraded condition. The degraded directivity was also assessed using the DI measure in an anechoic chamber. The perceptual directional benefit in each directivity-degraded condition was obtained by testing 10 hearing-impaired adults in a sound field with diffuse noise using the Hearing in Noise Test (HINT)., Results: The results of the DI and HINT measures showed strong correlation between the two FSRs (test chamber and sound field), while the two FBRs showed no correlation. The directivity generated by the FBRs could remain unchanged even when the directional microphone had lost more than 50% of its directivity. The results further indicated that the measures performed in the sound field were more reliable than those performed in the test chamber. Based on the results of the reliability measures, a 30% change in directivity was suggested as the referral threshold signifying defective directional systems., Conclusions: Because the FSR predicts the DI and HINT measurements more accurately than does the FBR, it is suggested that clinicians use the FSR to monitor hearing aid directivity. By using the FSR measure and informed by the suggested referral threshold, clinicians would be able to correctly identify defective directional microphone hearing aids at an early stage, rather than at a point when the directivity has been diminished completely or even reversed.

Objectives: The frequency-gain curve (FGC) is among the most important parameters to consider when fitting a hearing aid. In practice, a prescriptive FGC, derived from the audiogram, is initially applied. In the subsequent fine-tuning stage, the patient often communicates their concerns about the sound quality using descriptors (e.g., "it sounds hollow") and the clinician modifies the FGC accordingly. In this study, we present and evaluate a method that could enhance this process by rapidly mapping descriptors to FGC shapes. In addition, we begin to use this method to examine the extent to which there is across-individual agreement in how descriptors map to FGC shapes., Design: Ten listeners with hearing loss rated the extent to which each of a series of FGCs captured the meaning of a particular descriptor. Regression analyses were conducted to determine the degree to which these ratings were correlated with the gain values associated with each of 25 frequency bands. The array of slopes of these regression lines across frequency bands is termed the weighting function and was interpreted as the FGC shape that corresponded to the descriptor. We used this procedure to determine the FGC shapes associated with four of the most common descriptors used to describe hearing aid sound quality problems ("tinny," "sharp," "hollow," and "in a barrel, tunnel, or well")., Results: The weighting function shape was highly replicable despite variable listener responses, reached asymptotic performance quickly (<20 ratings), and was predictive of listener responses. On the global level, there was some agreement across individuals about how common descriptors mapped to weighting function shape. However, considerable differences were apparent between individuals in terms of the specifics of that mapping., Conclusions: The current approach for descriptor-to-FGC mapping is a quick, reliable method for determining individualized changes to the FGC. Given the range of individual differences in the specifics of the descriptor-to-FGC mappings observed, this approach could be useful in a clinical setting to easily quantify these acoustic parameters. Implementation of such procedures could lead to more personalized fine-tuning of amplification devices.

Objective: Ear-canal-based wideband reflectance (WBR) measurements may provide objective measures to assess and monitor middle-ear status in young babies. This work presents WBR measurements of power reflectance and transmittance on populations of healthy newborn babies (3 to 5 days) and healthy 1-mo-old babies (28 to 34 days). Thus, this work determines how power reflectance and transmittance vary between newborn and 1-mo-old babies and characterizes the range of these measures in normal populations., Design: Power reflectance and transmittance were calculated from pressure measurements made in the ear canals of seven newborn (12 ears) and eleven 1-mo-old (19 ears) babies. Permutation tests, t tests, and regression (random effects) models were used to test the effects of age (newborn versus 1 mo), gender, and ear side (right versus left)., Results: The power reflectance and transmittance did not differ significantly for the age comparison (newborn versus 1 mo), although the results suggest a possible difference between newborn and 1-mo-old ears near 2000 Hz. There were no differences between the male and female ears. There are small but significant differences between left and right ears in three frequency bands encompassing 500 to 4000 Hz, where the predicted power reflectance mean for the left ear differs from the right ear by 0.02 to -0.07 depending on the frequency band., Conclusions: At most frequencies, power reflectance and transmittance are indistinguishable for newborn and 1-mo-old healthy babies, with limited or no differences between the two age groups and the males and females. There were small differences in some frequency bands for left and right ears. The measurements made here are similar to other published results in some frequency ranges but differ in other frequency ranges; differences among other studies from neonatal intensive care unit babies, healthy newborn babies, and healthy 1-mo-old babies are discussed.

Objective: American Speech-Language-Hearing Association (ASHA) guidelines allow pulsed and warbled tones in measuring audiometric thresholds and include test frequencies of 3000 and 6000 Hz. However, no research has examined the relationship between thresholds obtained with these stimuli at these frequencies. This study investigated the relationship between thresholds obtained with pulsed, warbled, and pulsed-warbled tones., Design: Thresholds from 25 listeners were obtained using pulsed, warbled, and pulsed-warbled tones at test frequencies recommended by ASHA., Results: Thresholds elicited with pulsed, warbled, and pulsed-warbled tones did not significantly differ., Conclusions: Findings support using pulsed, warbled, and pulsed-warbled tones for threshold measurements at the frequencies recommended by ASHA.

Objective: A clinical protocol for diagnosing hearing loss (HL) in infants designed to meet early intervention guidelines was used with the goals of providing normative data for (1) frequency-specific tone burst auditory brain stem response (TBABR) thresholds by air conduction (AC) and bone conduction (BC) in early infancy used to classify type and severity of HL, (2) ear-specific behavioral thresholds for these same infants by 1 yr of age, and (3) the relationship between TBABR thresholds and behavioral thresholds for this group of infants., Design: AC- and BC-TBABRs were measured in young infants (mean age, <3 mo) under natural sleep to classify the type and severity of HL (conductive, sensorineural, or mixed). A small group of normal-hearing adults undergoing the same TBABR protocol served as a control group. Threshold and latency data for AC- and BC-ABR were analyzed for infants classified as having normal hearing and for those with and without conductive HL. The ability to detect conductive HL based on ABR latencies evoked by clicks presented at 80 dB nHL was assessed. Behavioral thresholds using visual reinforcement audiometry (VRA) were measured in infants at a mean age of approximately 10 mo. The relationship between TBABR and behavioral thresholds obtained in infancy was analyzed, and the prediction of behavioral thresholds from TBABR thresholds was examined., Results: Mean TBABR thresholds in young infants with normal hearing tested under natural sleep were similar to previously published data. The relationship between AC- and BC-TBABR thresholds differed as a function of stimulus frequency for infants but not adults. A mean air-bone gap (ABG) of 15 dB was present at 500 Hz even in normal-hearing infants, with those infants classified as having conductive HL presenting with substantially larger ABGs. Wave V latency functions for AC- and BC-TBABR also differed between infants and adults as a function of frequency. Infant BC-TBABR latencies were well matched between those with normal hearing and conductive HL, whereas AC-TBABR latency functions separated these groups. Mean VRA thresholds using insert phones in normal-hearing infants tested were between 14 and 17 dB HL for all three test frequencies at a mean age of 9.7 mo. Correlations between TBABR and VRA thresholds, both obtained during infancy, were strong for all three test frequencies (r = 0.86, 0.90, and 0.91 for 500, 2000, and 4000 Hz, respectively)., Conclusions: AC- and BC-TBABR results can be readily obtained in young infants under natural sleep and were used to classify the type of HL based on the absolute threshold and the size of the ABG. Differences in wave V latency functions for TBABR by AC and BC and wave I and V latencies of the high-level click ABR also distinguish between infants with and without TBABR ABGs. Ear-specific behavioral responses can be obtained at levels under 20 dB HL in normal-hearing infants younger than 1 yr using VRA, and these behavioral thresholds correlate well with TBABR thresholds obtained on average 6.5 mo previously in this population. The current results suggest that protocols for obtaining AC- and BC-TBABR and behavioral thresholds that meet guidelines for early intervention are clinically feasible.

Objective: The aim of this study was to examine the noise exposure and hearing of fishermen from small-scale fisheries from the state of Paraná in Brazil., Design: Participants of this cross-sectional study included 141 male fishermen, ages ranging from 18 to 77 yr old and 136 controls matched by socioeconomic level, age, and gender. We conducted personal noise dosimetry and interviewed the fishermen regarding their hearing and their job. Audiological testing performed included pure-tone audiometry in the 0.5 to 8 kHz frequency range, extended high-frequency audiometry in the 9 to 16 kHz range, and transient and distortion-product otoacoustic emissions. Testing was preceded by a period of at least 14 hr without exposure to noise. Participants were subdivided in subgroups according to their noise exposure history., Results: Sound level measurement results ranged from 38 to 58 Leq dB (A) in vessels without an engine and between 90 and 108 Leq dB (A) in vessels with an engine. Results from additional area sound level measurements conducted in five different seating locations in the 9HP engine boat ranged from 86 to 105 dB (A). Statistical analysis of the pure-tone audiometry results showed that fishermen with current or a history of occupational noise exposure had significantly poorer thresholds than controls or unexposed fishermen in several of the tested audiometric frequencies. Results of the otoacoustic emissions testing showed differences between exposed and unexposed groups regarding the presence of responses in bilateral amplitude and reproducibility at all frequency bands tested., Conclusions: Because of the fishermen's increased risk of hearing disorders, a variety of solutions are recommended, which include dissemination of information on control of noise emissions generated by the boat engines, audiological care, and hearing loss prevention services tailored to workers from small-scale fisheries.

Objectives: This study had two related purposes: first, to define the range of optimal ear canal levels of aided speech in both high frequency and low frequency regions for adults, using both subjective and objective definitions of optimal; and second, to determine whether a prescribed frequency response, such as that given by Desired Sensation Level [Input/Output], falls within the adult listener's optimal range., Design: Twenty-three adult listeners with mild to moderately severe sensorineural hearing loss were selected from a pool of research volunteers. They were fitted in the laboratory with the Siemens Signia hearing instrument and tested with 20 nominally different frequency responses. All advanced processing options of the hearing instrument were disabled. Subjective ratings of loudness and quality and objective measures of consonant identification were obtained for every frequency response., Results: These adult listeners had, on average, a 10 dB range of measured responses in both the low and the high frequencies that resulted in optimal performance on all the measurements. The range did not vary with degree or configuration of hearing loss, or previous hearing aid experience. Desired-Sensation-Level Input/Output targets were within the optimal range for the low frequencies, and 3 dB above the optimal range for the high frequencies., Conclusions: A range of aided ear canal frequency responses was determined within which adults with mild to moderately severe hearing loss performed optimally on both objective and subjective outcomes. Clinical implications of this finding include the following: prescriptive methods providing different targets may all result in optimal fittings; and a range of targets may be more appropriate than a single target when setting the frequency-gain characteristics of the hearing instrument.

Objective: The overall objective was to begin the investigation, in humans, of distortion product otoacoustic emission measurements, which are intended to be part of a diagnostic protocol being developed. This protocol, designed to distinguish among different cochlear hearing disorders, has been tested to date only through lesion studies in the gerbil (Mills, Ear and Hearing, 27, 508-525, 2006). To be applied successfully to human subjects, it was required that parameters and procedures for emission measurements be found, which resulted in sufficiently small intersubject variability in normal subjects, among other requirements. To attain these objectives, measurements of particular otoacoustic emission responses were made in a reference group of young adults having excellent hearing., Design: Twenty young adults (age 18 to 24 yr; 40 ears) comprised the subject group, with equal numbers of men and women. Inclusion criteria included hearing thresholds of 10 dB HL or better in both ears at all frequencies (0.5, 1, 2, 3, 4, 6, and 8 kHz), plus a tympanometric peak response located within +/-30 daPa of ambient pressure in both ears. The otoacoustic emission stimulus consisted of two tones (frequencies f1 and f2) varied in level using 5-dB steps with the lower-frequency stimulus level always 10 dB greater than that of the higher-frequency stimulus. The emission isoresponse threshold was defined to be the stimulus level required to obtain an emission amplitude of -10 dB SPL. Another potential measure was defined to be the emission amplitude at the highest stimulus levels routinely tested. Mean emission amplitudes and thresholds were determined for f2 frequencies equal to audiometric frequencies from 1 to 8 kHz, using two different stimulus frequency ratios, f2/f1=1.21 and 1.28., Results: One result of the study was the derivation of reference standards for the emission threshold level, similar to the HL scale for pure-tone thresholds. For use in diagnosis, the optimal measure was found to be the otoacoustic emission threshold for the stimulus frequency ratio f2/f1=1.21 and for f2 frequencies from 1 to 6 kHz. The f2 frequency of 8 kHz seemed less useful because the emission had a relatively high mean threshold. For frequencies 1 to 6 kHz, the variances were adequately small: 95% of the emission thresholds fell within +/-13 dB of the mean at each frequency, a variability only slightly larger than that for the gerbil. Finally, even within the 10-dB HL limit, responses showed a slight trend for increased emission thresholds with increased auditory threshold. Only at 8 kHz was the amount of covariance important, however, with the relationship between emission and auditory thresholds strongest for men., Conclusions: Emission reference standards can be developed by testing a group of young adults with excellent hearing. The diagnostic procedure previously proposed on the basis of gerbil lesion studies may be adapted with relatively little modification for use in human subjects. However, validity of the test and specific numerical results for human subjects remain to be firmly established for the purpose of distinguishing among different cochlear disorders.

Objective: To compare the auditory function of normal-hearing children attending mainstream schools who were referred for an auditory evaluation because of listening/hearing problems (suspected auditory processing disorders [susAPD]) with that of normal-hearing control children., Design: Sixty-five children with a normal standard audiometric evaluation, ages 6-14 yr (32 of whom were referred for susAPD, with the rest age-matched control children), completed a battery of four auditory tests: a dichotic test of competing sentences; a simple discrimination of short tone pairs differing in fundamental frequency at varying interstimulus intervals (TDT); a discrimination task using consonant cluster minimal pairs of real words (CCMP), and an adaptive threshold task for detecting a brief tone presented either simultaneously with a masker (simultaneous masking) or immediately preceding it (backward masking). Regression analyses, including age as a covariate, were performed to determine the extent to which the performance of the two groups differed on each task. Age-corrected z-scores were calculated to evaluate the effectiveness of the complete battery in discriminating the groups., Results: The performance of the susAPD group was significantly poorer than the control group on all but the masking tasks, which failed to differentiate the two groups. The CCMP discriminated the groups most effectively, as it yielded the lowest number of control children with abnormal scores, and performance in both groups was independent of age. By contrast, the proportion of control children who performed poorly on the competing sentences test was unacceptably high. Together, the CCMP (verbal) and TDT (nonverbal) tasks detected impaired listening skills in 56% of the children who were referred to the clinic, compared with 6% of the control children. Performance on the two tasks was not correlated., Conclusions: Two of the four tests evaluated, the CCMP and TDT, proved effective in differentiating the two groups of children of this study. The application of both tests increased the proportion of susAPD children who performed poorly compared with the application of each test alone, while reducing the proportion of control subjects who performed poorly. The findings highlight the importance of carrying out a complete auditory evaluation in children referred for medical attention, even if their standard audiometric evaluation is unremarkable.

Objective: To develop a new version of the threshold-equalizing-noise (TEN) test for the diagnosis of dead regions, with levels calibrated in dB HL rather than dB SPL, and with levels corresponding to the dial readings on the audiometer., Design: The spectral shape of the noise required to give equal masked thresholds at all frequencies, when expressed in dB HL, was derived by two calculation methods and by empirical measurements of the electrical output of audiometers using TDH50 earphones and TDH39 earphones. To reduce the loudness of the noise and to minimize distortion generated in the audiometer and/or earphone, the noise was bandlimited between 354 and 6500 Hz. In addition, the noise was synthesized using a method that leads to a low crest factor (ratio of peak to root-mean-square value). This further reduced audiometer/earphone distortion and allowed higher levels per ERBN; ERBN is the equivalent rectangular bandwidth of the auditory filter at 1 kHz, as determined in young, normally hearing subjects. The test tone frequencies were limited to the range 500 to 4000 Hz. Subjects with normal or near-normal hearing were tested by using a noise level of 60 dB HL/ERBN to assess whether the noise did lead to equal masked thresholds in dB HL for all audiometric frequencies from 500 to 4000 Hz. Thresholds in the TEN were measured by means of manual audiometry with a 2 dB final step size., Results: The mean masked thresholds were almost constant across frequency when expressed in dB HL and were within 0.5 dB of the noise level per ERBN. For a single noise level, the test takes approximately 5 minutes per ear to administer., Conclusions: The new TEN test has the following advantages over the original version (which used levels calibrated in dB SPL): (1) All levels are expressed in dB HL. Thus, absolute thresholds only need to be measured once. (2) Calibration is such that both the noise level/ERBN and the test tone levels correspond to the values indicated on the audiometer. This makes the test simpler to apply and reduces the likelihood of errors. (3) The noise bandwidth is restricted, and the noise has a low crest factor. This allows the noise level/ERBN to be increased while avoiding distortion, excessive loudness, and possible further damage to hearing.

Objective: This study was undertaken to determine the relationship between extended-high-frequency (EHF) hearing losses and wideband middle ear impedance in children with chronic otitis media (OM) histories., Design: Children with OM histories were selected from a prospective study cohort if they had normal tympanograms, no air-bone gaps, and no otoscopic evidence of active OM at the time of testing. OM subjects were divided into two groups, those with Better Hearing in the EHF range and those with Worse Hearing in the EHF range. The OM groups were compared with an age-matched, healthy Control group that had no more than five documented episodes of OM and no more than two in any 1 yr. All children were 9 to 16 yr of age. Subjects were tested by standard audiometric methods in the conventional audiometric range (0.25 to 8.0 kHz) and the EHF range (8 to 20 kHz). Middle ear impedance and reflectance were measured with an experimental system over the frequency range 0.25 to 10.08 kHz., Results: The Worse Hearing OM group had slightly poorer hearing in the conventional audiometric frequency range compared with the other two groups. The Better Hearing OM group and the Control group had nearly identical EHF hearing. The Worse Hearing OM group had significantly poorer EHF hearing compared with the other two groups, the difference increasing exponentially with frequency. Middle ear impedance differences among groups were confined to low frequencies (<2 kHz). The Control group had significantly higher negative reactance than the two OM groups. There were no significant group differences in impedance or reflectance in the high frequencies (2 to 10 kHz)., Conclusions: The results of this study confirm those of previous reports that children who have recovered from chronic OM have significantly poorer hearing in the EHF range compared with children without significant OM histories. The EHF hearing losses that occur in children with OM histories are strongly frequency dependent, suggesting a preferential effect on the base of the cochlea. Middle ear impedance and reflectance differences do not account for the EHF hearing losses observed in children with OM histories. The results support the hypothesis that OM-related EHF hearing losses are cochlear in origin.

Objective: The aim of this study was to identify auditory frequencies at which serial threshold testing would provide the greatest sensitivity for early detection of ototoxicity. The overall objective is to develop a more time-efficient ototoxicity monitoring protocol., Design: Threshold data were analyzed from 370 hospitalized patients treated with aminoglycoside antibiotics (AMGs) or cisplatin (CDDP) who received serial auditory monitoring before, during, and after treatment at conventional (0.25 to 8 kHz) and high (9 to 20 kHz) frequencies., Results: For patients showing hearing changes due to ototoxicity, a frequency range was identified for its apparent high sensitivity to initial ototoxicity. This sensitive range is identified according to an individual's hearing threshold configuration, and is, therefore, unique for each patient. The range consists of five frequencies, generally separated by 1/6 octave, e.g., 8, 9, 10, 11.2, and 12.5 kHz. To determine frequencies and combinations of frequencies that were most often involved in ototoxicity detection, threshold data in the sensitive range were analyzed in detail. This analysis suggests that patients receiving treatment with AMG or CDDP can be monitored for hearing thresholds at only five frequencies, resulting in an 84% detection rate for AMG and 94% for CDDP compared with monitoring at all conventional and high frequencies., Conclusions: This comprehensive analysis supports earlier observations that a sensitive, limited frequency range exists in which serial threshold monitoring will provide early warning of ototoxicity before effects in the speech frequency range. This finding is now being evaluated in a prospective investigation.

Objective: To demonstrate a technique for objectively calibrating bone conductors on an individual basis using distortion product otoacoustic emissions (DPOAEs)., Design: Individual calibrations were obtained using DPOAEs recorded from a single ear of 21 normally hearing adults. Validity and robustness of the technique were investigated through subjective phase cancellation measurements and sensitivity analysis., Results: Calibrations obtained using the DPOAE method were well supported by phase cancellation results. Intersession repeatability was good, and manipulation of the DPOAE data showed that the calculated calibration is relatively insensitive to small variations of emission magnitude. Bilateral stimulation through bone conduction did not display an apparent effect on emission magnitude in a single individual., Conclusion: Bone conductors can be accurately calibrated on an individual basis with good repeatability using DPOAEs. The technique is robust and offers an objective, noninvasive calibration method for research and specialized clinical applications. No training and only passive cooperation are required, making the procedure ideal for special groups such as children. A number of limitations will reduce the clinical utility of this technique. Important audiometric frequencies below 1 kHz cannot be tested because of noise, because individuals with significant hearing loss are unlikely to produce sufficient DPOAEs, and because commercial bone conductors typically have poor high-frequency response above 4 kHz.

Therapeutic drugs such as the aminoglycoside antibiotics (AMG) and the chemotherapy agent cisplatin (CDDP) are known to cause irreversible hearing loss, typically affecting highest frequency hearing first with progression of loss to the lower frequency regions. Conventional (0.25-8 kHz) and high-frequency (9-20 kHz) serial hearing threshold monitoring was done in 123 hospitalized patients (222 ears) administered AMG or CDDP. Of ears showing a decrease in sensitivity corresponding with treatment, 62.5% demonstrated initial hearing loss solely in the high-frequency range, 13.5% first showed loss only in the conventional-frequency range, and 24.0% showed loss in both frequency ranges concurrently. Thus, if only high frequencies had been monitored, early change in auditory sensitivity would have been detected in 86.5% of these patients. Further analysis revealed a range of five frequencies, specific to each individual's hearing threshold configuration, in which initial ototoxicity appeared most likely to be detected. Testing only these five frequencies would have identified 89.2% of ears that showed change. The results of this study confirm the need to serially monitor auditory thresholds, especially in the high-frequency range, of patients receiving ototoxic drugs. A shortened five-frequency monitoring protocol is presented and suggested for use with patients unable to tolerate lengthy audiometric testing procedures.

This study investigated the feasibility of using a localization task to rule out unilateral hearing loss in infants. Fourcorner localization ability was assessed in 29 normal-hearing infants (9-20 mo) using four different test stimuli. In these same infants, a mild unilateral hearing loss was simulated by occlusion of the external auditory canal and the test sequence was repeated. Analysis of front-back, right-left, and combined errors for each of the test stimuli revealed that this type of task may allow detection of unilateral hearing loss as slight as 25 dB HL.

Intratester test-retest reliability of the real ear unaided response (REUR) was determined on 49 ears using the Frye 6500 real ear analyzer. Results revealed mean differences of less than 1 dB for repeat measurements at seven test frequencies between 250 and 4000 Hz. The average peak resonant frequency of the repeated measure was within 16 Hz of the initial measure. In addition, the intersubject variability of the amplitude of REUR was quite large. A range of 7 dB was found at 250 to 500 Hz with the range expanding to 15 to 20 dB at 2000 to 4000 Hz. Also, the peak resonant frequency varied between 2100-4800 Hz. These results are discussed in terms of those dispensers who use the REUR to "custom" order hearing aids.

This study examined test-retest reliability of infant auditory thresholds in a single evaluation session. Eight- to 11-month-olds were assessed in both operant and nonoperant audiometric procedures. Operant testing produced an average of 8.5 thresholds. Mean threshold level did not shift significantly over the course of the operant session, although some individual threshold functions varied from the group trend. Nonoperant assessment yielded two or more measures of threshold for only a portion of the subject group. The pattern of repeated measures for this subgroup showed a significant upward shift in threshold level.

Test and re-test high-frequency (10-20 kHz) thresholds were obtained for 200 ears of 100 normally hearing (0.25-8 kHz) young adults (18-28 years old) using a Beltone 2000 audiometer and Sennheiser HD 250 earphones referenced to sound pressure levels developed in a Bruel and Kjaer flat-plate coupler. Normative high-frequency thresholds could not be recommended for clinical use due to the very large intersubject threshold variability. This occurred even though test versus re-test thresholds were not significantly different (p greater than 0.05) at any frequency. However, comparisons of the test minus re-test threshold for individual ears were within a clinically acceptable range of +/- 10 dB for at least 95% of the ears at each frequency. Future research should concern intrasubject threshold reliability and variability rather than specifying intersubject normative thresholds.

The attenuation provided by TDH earphones in MX-41/AR and P/N 51 cushions, Audiocup earphone enclosures and ER-3A insert earphones with ER3-14 foam earplugs was determined for 30 normally hearing subjects using a real-ear attenuation at threshold paradigm. The MX-41/AR and P/N 51 cushions provided about the same amount of attenuation which was less than the attenuation provided by the Audiocup enclosures. The ER-3A/ER3-14 provided the highest amount of attenuation. The MX-41/AR and ER-3A/ER3-14 attenuation values were in agreement with other studies using similar methodology. However, the attenuation provided by the Audiocup enclosures was considerably less, in the lower frequencies, than reported in two other studies. ANSI S3.1-1977 supra-aural earphone cushion attenuation values, which were determined using pure-tones presented in a free-field, should be replaced by earphone cushion attenuation values determined with 1/3 octave bands of noise presented in a diffuse sound field.

This is an investigation of the accuracy with which the 40-Hz evoked potential (EP) threshold can be used to predict low frequency behavioral audiometric thresholds. The EP thresholds for 500 and 1000 Hz tone bursts were compared with behavioral thresholds obtained from 40 hearing-impaired ears. Correlation coefficients (between EP and behavioral thresholds) of 0.79 and 0.87 were obtained for the 500 and 1000 Hz signals, respectively. Confidence intervals for EP estimates of behavioral thresholds were -10 to +30 dB for 500 Hz signals and -20 to +20 for 1000 Hz. Problems associated with the use of the EP for predicting behavioral thresholds are discussed.

Our purpose was to investigate the influence of acoustic radiation produced by bone vibrators at 4000 Hz on bone conduction (BC) testing. In one study, BC thresholds were obtained with a Radioear B-70A, B-71, and B-72 vibrator when the subject's ear canal was unoccluded and occluded. In another study, probe-tube microphone measurements were made just inside the entrance to the ear canal for each vibrator and for an air conduction source at comparable sensation levels. Results of both studies were interpreted to indicate that the B-70A and B-71 produced minimal acoustic radiation. However, the B-72 was found to have excessive acoustic radiation which would be sufficient to influence BC thresholds and produce an invalid high-frequency air-bone gap.

Differences in the Bekesy tracking levels of continuous (C) and interrupted (I) tones at both threshold and most comfortable loudness (MCL) were determined in a large clinical sample of persons with hearing loss. Results indicate small but significant C-I differences not only at the two levels separately but also in the tracking of C and I tones at threshold relative to MCL, regardless of frequency or hearing loss severity. Such results may have implications for both diagnostic and rehabilitative audiology.

We discuss our experience with evaluation of 167 children by auditory brainstem response audiometry in 1978. We summarize experience with referral sources, medication for sedation, and interpretation of test outcome. Medication for sedation was required for 136 children. Concommitant central nervous system involvement rendered auditory brainstem response ambiquous in some children; however, the technique still provide useful information about status of peripheral auditory sensitivity obtainable in no other way. Finally, agreement among auditory brainstem response, behavioral, and impedance audiometry predictions was usually quite good.

This paper is the first in a series of three concerning audiological tests and test batteries designed to differentiate cochlear from retrocochlear site-of-lesion. This paper concentrates on the techniques of clinical decision analysis with particular application to audiology. Those principles of clinical decision analysis which are most relevant for the audiologist are presented. Several techniques for measuring test performance are described and evaluated. In addition, this paper considers the problem of comparing test performance to determine the superior test.

Different types of hearing aid test equipment use different methods to calculate total harmonic distortion (THD). Comparisons of the THD measured by four commercially available systems were made by evaluating eight hearing aids, three times each. The results obtained were significantly different (p less than 0.001) among three of the test instruments. Furthermore approximately 10% of the hearing aids, which met the ANSI S3.22-1976 specifications for THD when tested with an apparatus that measures true THD, failed this measurement when evaluated on the other three systems.

It has been suggested that hearing level might be assessed by comparing the acoustic reflex thresholds (ARTs) for two modes of stimulation: by pure tones alone and by a combination of two pure tones, one of which is used as a "preactivator." Using an extrapolatory method for determining the reflex thresholds, 35 subjects (17 normal hearing and 18 hearing impaired) were used to test the above hypothesis. For the individual frequencies 75% of the hearing levels estimated from the ARTs lay within +/- 10 dB of the true threshold, and 97% within +/- 20 dB. However, although the method does appear to be more accurate than the Niemeyer and Sesterhenn method of estimating hearing loss from the ARTs for pure tones and noise bands, it has limitations due to the high levels of preactivating tone required, and the number of stimuli it is necessary to use. Some possible refinements are suggested that might improve the clinical applicability of the technique.

This research determined the influence of temperature on the output of two Bruel and Kjaer 4930 mechanical couplers using a Radioear B-71, B-72, and a Pracitronic KH 70 bone vibrator. When the temperature of the mechanical couplers was varied from 17 degrees C (62.6 degrees F) to 29 degrees C (84.2 degrees F) in steps of 3 degrees C (5.4 degrees F) and the bone vibrators had a constant temperature, the output of each mechanical coupler systematically decreased as its temperature increased for each bone vibrator type. The largest output differences for both couplers and each vibrator occurred at 4000 Hz. The average of these differences across the couplers and vibrators was 6.6 dB higher at 17 degrees C than at 29 degrees C which dB/3.6 degrees F). When the temperature of the bone vibrators was 17 and 29 degrees C and the mechanical couplers were maintained at a constant temperature, there were little or no differences in the output of the mechanical couplers. The temperature of a mechanical coupler rather than that of the bone vibrator is a critical variable in bone conduction calibration. Mechanical coupler temperature-dependent output coefficients were determined for use in bone conduction calibration from 250 to 4000 Hz for all three bone vibrator types and at 6000 and 8000 Hz for the KH 70.

Acoustic reflex amplitude data were obtained for 92 subjects. Uncrossed (ipsilateral) and crossed (contralateral) acoustic reflex activity was measured simultaneously and computer averaged with specially constructed apparatus. For all subjects, amplitude was greater for uncrossed than crossed acoustic reflexes. The ratio of maximum uncrossed versus crossed reflex amplitude for young normal-hearing subjects ranged from 1.06 to 2.38, with an average of 1.50. This relationship was not significantly influenced by subject age, sensorineural hearing impairment, or mild abnormalities in acoustic immittance. Clinical investigation of the diagnostic application of the uncrossed versus crossed reflex amplitude ratio in central auditory nervous system pathology is suggested.

It was the objective of this preliminary investigation to determine whether psychoacoustic tuning curves could be obtained on naive listeners utilizing a sweep, frequency-modulated masker. Psychoacoustic tuning curves were obtained on 10 normal-hearing young adult listeners. A simultaneous masking paradigm was utilized. The probe tone was a 2 kHz signal and the masker was a sweep, frequency-modulated tone between and including 750 Hz and 4 kHz. A mean Q value of 4.93 with a standard deviation of 0.85 was obtained from the subjects. Clinical implications and needs for further research are discussed.

Although a great deal of information is available concerning cardiovascular responsitivity to sensory stimuli, little is known regarding the pragmatic application of cardiac response measures to the problems of audiological assessment. Some relationships between arousal systems and cardiovascular function have begun to emerge, and the assessment of communicative behavior using HR response measures has become a more realistic goal, but the clinician who desires to utilize these techniques for audiological evaluation faces serious difficulties until further basic research has been conducted. Eisenberg (9) observed that instrumentation for measuring HR changes to auditory stimuli was research oriented and that measurement of HR data, although holding promise for the future, could not be realistically viewed as a clinical tool for audiological evaluation. Indeed, Eisenberg challenged audiologists to suspend the clinical application of these procedures until sufficient basic research evidence has accumulated to operationally define the problems at hand. Until that challenge is met, cardiotachometry will remain only a potentially rewarding procedure for assessment of the auditory system.

We used cost-effectiveness analysis to compare two strategies for screening for severe hearing loss in the neonatal intensive care unit (NICU): the auditory brain stem response (ABR) and the Crib-O-Gram (COG). We studied hypothetical cohorts of infants using data derived from the literature on screening test characteristics. We included the costs of initial screening and those of further diagnostic testing for infants who fail the screening test. The ABR cost more per test administered than COG, but had higher sensitivity and specificity to detect hearing loss. We found the ABR, therefore, to be more cost effective than the COG. Using best-estimate assumptions, ABR cost $10,610 for each correctly detected case of hearing loss; COG cost $14,310 for each correctly detected case; among every 1,000 NICU infants screened, furthermore, ABR detected all cases of hearing loss, whereas COG failed to detect five hearing-impaired infants. We conclude that cost-effectiveness analysis justifies using ABR as a screening tool.

Interjudge validity and intrajudge reliability were studied in a task in which three sets of judges (scores) identified middle latency responses under varying conditions of intensity and number of stimuli per response. The results demonstrated that intensity level was the only factor that had a statistically significant effect on the scorers' judgments. As intensity decreased it became increasingly difficult to detect middle latency responses; however, silent controls were clearly identified as response absent. Definite trends were seen for the scorer groups as a function of experience; the experienced groups generally had slightly higher mean confidence levels and percent correct judgments than the naive scorers. Surprisingly, increasing the number of stimuli had no significant effect on the scorers' judgments. Last, intrajudge reliability was high across all scorers for all conditions except at 10 dB SL. Most of the unreliable judgments and difficulty in detection (interjudge validity) occurred at the 10 dB SL.

This paper is the second in a series of three concerning audiological tests and test batteries designed to differentiate cochlear from retrocochlear site-of-lesion. The first paper discussed the application of clinical decision analysis to diagnostic tests, particularly audiological tests. This paper uses the techniques of clinical decision analysis to evaluate the clinical performance of audiological, vestibular, and radiological tests based on data derived from the last 15 years of the clinical literature. Using calculated measures of test performance, we compared and divided the test into four groups.

A retrospective, cross-sectional analysis of component latencies of the auditory brain stem response (ABR) was performed on 466 patients ranging in age from 30 weeks postconception to adulthood. The ontogeny of ABR component wave latencies was adequately described by two exponential curves having different slopes; the steeper curve represented an early, rapid maturation ending by 8 to 10 weeks post partum, and the ensuing, more gradual curve corresponded to developmental events which were completed by the beginning of the third year of extrauterine life. These observations conform to previous maturational concepts of peripheral versus central segments of the auditory pathway and to the gradual decrease in interwave latencies with increasing age. Unlike interwave latency, however, the ratio of the latencies of selected component waves was constant with increasing age. This was especially apparent in developing newborns less than 50 weeks postconception. The nonlinear bases of this phenomenon are outlined, and the insights which stem from this perspective are discussed.

Babies (N = 642) were tested for auditory disorder, using the auditory brain stem response (ABR), at the time of their discharge from a tertiary intensive care nursery (ICN). Of those with ABR threshold elevation in one or both ears (N = 97), 61% (N = 59) were retested some months later by a battery of audiological tests; 21 (N = 3.3% of the 642) suffered binaural peripheral loss and 11 (1.7%) now wear hearing aids. These new data, when combined with similar data previously reported from the same ICN, yield a sample of 1613 babies examined during a 5.8-year period from which these conclusions emerge: (1) About 16% of our ICN babies leave the hospital with reduced sensitivity in one or both ears; (2) the hearing deficiency is permanent for 8 to 10%; (3) the loss is sensorineural, bilateral, and so severe for about 4% that hearing aids will be required to optimize their language and psychosocial development. Use of the ABR procedure for neonatal hearing testing is the target of several criticisms: it is being applied too early in life; its predictions about permanent hearing loss are unacceptably inaccurate; or/and it is too costly. We discuss these and still other objections that have been raised.

The general routine for recording the auditory brainstem responses (ABR) includes the use of earlobe electrodes as reference. Electrically linked electrodes on each side of the neck are almost indifferent with regard to the ABR, and such electrodes were used as reference in an analysis of the response patterns at the vertex and both earlobes. These contribute very significantly to conventional recordings, and it is preferable to use an indifferent electrode as reference for the active vertex electrode. If this measurement is supplemented with a differential recording between the 2 earlobes, the N1 of the whole nerve action potential and other parts of the early ABR are easy to identify and the diagnostic possibilities in pathological cases will be improved.

Digital filtration with zero and standard-phase shift characteristics was performed on unfiltered auditory evoked potentials recorded from 10 adult subjects. Standard-phase shift filters were seen to distort the response. Mild phase shift distortion often augmented the IV/V-Na1 amplitude (auditory brain stem response). When recording the IV/V-Na1 amplitude on a narrow timebase (20 msec), we recommend using a phase shift filter that has a high-pass cutoff frequency approximating 15 Hz and a slope of 12 to 24 dB/octave, in order to take advantage of the observed phase shift augmentation. The augmentation of the IV/V-Na1 amplitude is at the expense of the IV/V-Na2 amplitude. Thus, this phase shift distortion is not desirable if a long timebase (50 msec) is used. If a high-pass standard-phase shift filter of 100 Hz is used to eliminate muscle artifact, a reduction in the IV/V-Na1 amplitude from phase shift distortion is seen compared to the zero-phase shift control. In site-of-lesion testing, a nondistorted waveform produced by digital zero-phase shift filtration is also desirable over a distorted analog response. It is recommended that the slow wave activity of the response be recorded with a timebase of at least 40 to 50 msec and with a filter that produces minimal or no phase shifting. The major recorded response will be the Na trough and Pa peak. Evoked response units with steep filters will phase shift the response and produce a reduction in the IV/V-Na amplitude and a concomitant augmentation of the latter middle latency response waveforms.(ABSTRACT TRUNCATED AT 250 WORDS)