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BACKGROUND Higher probe tone frequencies have been shown to increase the elicitation rates in electrically evoked stapedius reflex threshold (eSRT) measurements. OBJECTIVES To determine the optimal probe tone frequency for contralateral eSRT measurements at individual electrodes in children with unilateral cochlear implants and to assess the relationship between eSRTs for this frequency and most comfortable levels (M-levels). MATERIALS AND METHODS Contralateral eSRT measurements with three probe tone frequencies (226, 678, and 1000 Hz) at individual electrodes were performed on 26 paediatric Advanced Bionics cochlear implant recipients. RESULTS The elicitation rates of eSRTs for 226, 678, and 1000 Hz probe tones were 73.08% (57/78), 88.46% (69/78), and 88.46% (69/78), respectively. The average eSRT for the 1000 Hz probe tone was significantly lower than those for 226 and 678 Hz probe tones (p

This method might be an effective intra-operative way to access hearing threshold under general anesthesia in the operating room.To develop an intra-operative hearing monitoring method for surgeons to access hearing threshold under general anesthesia in the operating room.System establishment and calibration was done firstly. Normal hearing (NH) and conductive hearing loss (CHL) participants were recruited. This study applied pure tone audiometry (PTA) to all subjects and tone pip ABR (tp-ABR) via loudspeakers in sound booth and operating room for NH and CHL subjects, respectively. For NH subjects, Bland Altman was conducted to compare 1k Hz PTA and tp-ABR threshold. For CHL participants, Paired t-test, Satterth waite t'-test, and linear correlation analysis were used to compare the two methods. p .05 was considered statistically different.(1) Bland Altman showed all plots were inside the 95% confidence interval, indicating that there was no difference between the two methods for NH subjects. (2) The two methods had a high correlation (Pearson's coefficient =0.872 0.6, p .05) in assessing hearing threshold in the operating room. (3) Satterth waite t'-test showed the ossicular chain malfunction enlarged the deviation of threshold by the two methods (.01 p .025).

Conclusion This study demonstrated excellent hearing recovery following the combined treatment of diuretic and oral steroid, and electrocochleography (ECoG) was significantly higher than normal side. This study reports characteristics of acute low-tone hearing loss (ALHL) that show the greater low-tone hearing loss, the higher ECoG, and excellent recovery, even-though low-tone hearing loss is worse, which can be different compared with sudden deafness. Objective To analyze ALHL without vertigo, this study compared the ALHL group with all patients exhibiting low-tone hearing loss and ear fullness. Hearing changes and vestibular functions were analyzed. Materials and methods ALHL was defined as a mean hearing loss of ≥ 30 dB at 125, 250, and 500 Hz, and ≤ 20 dB at 2, 4, and 8 kHz. From 156 cases of low-tone hearing loss of more than 10 dB without vertigo, 31 met the ALHL criteria and were subjected to audio-vestibular assessments including PTA, ECoG, vestibular evoked myogenic potential (VEMP) testing, and caloric testing. Results In ALHL, low-tone hearing loss was 42.7 ± 9.5 dB, and 83.9% of ALHL significantly recovered by more than 10 dB. The ECoG in ALHL was 0.334 ± 0.11 (higher than 0.25 ± 0.08 on the normal side) and ECoG abnormality was 35.5% (the greater low-tone hearing loss, the higher ECoG value).

The investigated experimental coding strategies significantly improved tone identification as compared with the participants' everyday audio processor settings. However, this benefit could not be attributed entirely to temporal fine structure stimulation but seems to be caused by decreasing the lower corner frequency of the filter bank. The 6 week habituation period used in this study might have been too short to allow the listeners to derive additional lexical information from the unfamiliar stimulation patterns.To evaluate a cochlear implant coding strategy that explicitly conveys temporal fine structure information in the context of the tonal language Mandarin.The study was designed as a longitudinal, monocentric, prospective, controlled, and randomized cross-over study and included 12 postlingually deafened adults, who were experienced cochlear implant users. Two experimental coding strategies, one of which explicitly presents temporal fine structure information, were compared to the participants' personal TEMPO+ speech processors, which do not convey fine structure information.Both experimental coding strategies improved tone identification by approximately 11 percentage points. This improvement was significant in the female speaker test. Sentence perception, as assessed with the M-HINT test, and quality of life scores were identical with all three coding strategies.

Not stimulating the apical cochlear region in tonal language speaking cochlear implantees significantly reduces discrimination of Mandarin vowels. The data presented here suggest that electrode arrays that allow complete cochlear coverage with stimulation pulses seem to be preferable over shorter arrays for use in cochlear implant (CI) indications.To assess the contribution of electrical stimulation beyond the first cochlear turn on tonal language speech perception.Twelve Mandarin-speaking users of the MED-EL COMBI 40+ cochlear implant with complete insertion of the standard COMBI 40+ electrode array participated in the study. Acute speech tests were performed in seven electrode configurations with stimulation either distributed over the whole length of the cochlea or restricted to the apical, middle or basal regions. The test battery comprised tone, consonant, and vowel identification in quiet as well as a sentence recognition task in quiet and noise.While neither tone nor consonant identification depended crucially on the placement of the active electrodes, vowel identification and sentence recognition decreased significantly when the four apical electrodes were not stimulated.

The longitudinal findings presented in this study suggest that with the maturational development, the conduction time of the auditory nerve decreases while the thresholds had no physiological changes within 0-6 months after birth. Comparing the tone-pip auditory brainstem response (ABR) with the auditory steady-state response (ASSR), the former had lower thresholds than the latter at 500-8000 Hz, which indicates that the estimation of tone-pip ABR maybe nearer to the actual hearing level of infants.To evaluate the feasibility of tone-pip ABR and ASSR for newborns and infants, and to follow the development of the threshold estimates from tone-pip ABR and ASSR in normal infants through the first 6 months of life.The tone-pip ABR and ASSR thresholds were measured at octave frequencies from 250 to 8000 Hz bilaterally in 80 infants aged 0-6 months with normal hearing.For click ABR at 70 dB nHL, the absolute and inter-peak wave latencies decreased as the age increased. The tone-pip ABR had similar waveforms to the click ABR, its wave latencies decreased and the waveforms improved as the age and frequency increased. On average, the thresholds of tone-pip ABR and ASSR were observed at 1.2-41.2 dB nHL (SD = 2.6-8.0 dB) and 16.9-43.0 dB nHL (SD = 2.5-8.0 dB), respectively, at 250-8000 Hz in infants aged 0-6 months, but there were no physiological differences. Tone-pip ABR thresholds were significantly lower than those for ASSR except at 250 Hz (p0.05). Both ASSR and ABR had stable and similar audiograms in the different groups.

Conclusion. High-frequency overstimulation can cause the loss of duration selectivity in low-frequency inferior colliculus neurons in guinea pigs. Objective. To investigate the effect of high-frequency overstimulation on duration tuning in low-frequency inferior colliculus neurons in guinea pigs. Materials and methods. Duration tuning pattern was recorded by measuring the spikes of single neurons in response to the best frequency (BF) of different durations. The effect of high-frequency overstimulation was verified by comparing the responses before and after the tone exposure. Results. In total, 40 duration-tuned neurons were successfully recorded before and after the tone exposure. After the high-frequency tone trauma, a total of 29 neurons (72.5%) became non-duration-tuned.

Conclusion. This study demonstrated that the artificial neural network can successfully classify Mandarin Chinese tone patterns produced by multiple children. The neural network can be used as an objective way of evaluating tone production of children. Objectives. Traditionally, tone production is evaluated subjectively using human listeners. The aim of the present study was to investigate the efficacy of using an artificial neural network in evaluating tone production of Mandarin-speaking children. Subjects and methods. Speech materials were recorded from 61 normal-hearing children. The fundamental frequency (F0) of each monosyllabic word was extracted and then used as inputs to a feed-forward backpropagation artificial neural network. The number of inputs was set at 12, whereas the number of hidden neurons was set at 16 in the neural network. The output layer consisted of four neurons representing the four Mandarin tone patterns. The tone recognition performance of the neural network was further compared with that of native Mandarin-speaking adult listeners. Results. The neural network successfully classified the tone patterns of the 61 child speakers with an accuracy of about 85% correct. This high accuracy exceeded the tone recognition performance by the adult listeners. Individual child speakers showed varied tone production accuracy as recognized by the adult listeners or by the neural network.

Objective To evaluate the short-term effects of varying the number and location of programmed electrodes on Mandarin tone perception in young children using Nucleus CI 24 implants. Material and methods Six children using CI 24 implants participated in the study. The Mandarin tone recognition of each subject was assessed using a self-designed word list containing 80 words under 5 different map conditions. The map conditions were: (i) the subject's current map with all functional electrodes; (ii) removing (i.e. not programming) the even-numbered active electrodes; (iii) removing the five most apical electrodes; (iv) removing the six most basal electrodes; and (v) removing all electrodes except the six most apical. Results Reducing the number of active electrodes caused a small but significant decrease in performance of Mandarin tone perception. However, a relatively high tone perception score (58.1%) could be maintained even when subjects used only six apical electrodes. The location of the electrodes, i.e. apical or basal, did not appear to be important in tone perception. For each individual tone, the scores for tones 1 and 4 were significantly higher than those for tones 2 and 3 for all map conditions. Comparing tone perception with word recognition, reducing the number of active electrodes had a much more negative effect on word recognition. Conclusions A small but significant decrease in Mandarin tone perception was observed when the number of active electrodes was reduced in children using CI 24 implants. The location of the electrode is not important in tone recognition. Moreover, tone recognition is far more resistant than word recognition to the negative effects of reducing the number of active programmable electrodes, possibly because it relies mostly on temporal envelopes while word recognition requires more spectral details.

The aim of this study was to test for differences between normal-hearing and hearing-impaired listeners regarding two fundamental aspects of intensity perception: loudness integration and loudness summation. Loudness functions for three different stimuli were measured using categorical loudness scaling in 8 normal-hearing and 12 hearing-impaired subjects. The results indicated that temporal loudness integration, defined as the difference in SPL between 16.25-ms and 300-ms noise bursts of equal loudness, was larger in the hearing-impaired than in the normal-hearing listeners. Loudness summation, defined as the difference in SPL between a 300-ms, 1,600-Hz tone pip and a white noise burst of the same duration and loudness, did not differ between the two groups. Implications of these results for hearing aid fitting strategies based on loudness normalization are discussed.

Although some findings suggest that auditory efferent fibers are involved in perception in noise, their function remains controversial. The contralateral suppression of evoked otoacoustic emissions (EOAEs) has recently provided a means of exploring the medial olivocochlear system (MOCS) in humans. In an experiment based on this paradigm, the present study examined the relationships between variations of both EOAEs and detection-in-noise thresholds, induced in the same subjects by a contralateral 50-dB-SPL broad-band noise masker. EOAEs were recorded in response to a burst of a multitone complex composed of 1, 1.5 and 2-kHz components. The detection thresholds of this 3-component complex were measured at 2 ipsilateral noise levels: 50 and 70 dB SPL. The main finding was a significant correlation between EOAE suppression and threshold variations under contralateral masking. A relationship was also found between the contralateral suppression of EOAEs and threshold variation induced by the increase in ipsilateral noise level. These findings support the notion that the MOCS is involved in the detection of multicomponent stimuli in noise.

In prelingually deaf children with cochlear implants, tone perception and production performance are highly correlated. This result is consistent with the hypothesis that tone perception is the prerequisite for good tone production.Previous research has shown remarkable deficits in tone perception and production in native tone language-speaking, prelingually deafened children with cochlear implants. The purpose of the present study was to investigate the relationship between tone perception and production in those children.Twenty-five prelingually deaf children with cochlear implants participated in the study. All subjects were Advanced Bionics CII/90K users with various lengths of implant use. To evaluate tone perception performance, subjects completed a computerized tone contrast test. For tone production performance, an artificial neural network was used to evaluate the accuracy of tones recorded from each of the 25 subjects.Large individual differences in tone perception and production performance were observed in these subjects. Tone perception accuracy ranged from 50.0 to 96.9% correct (chance performance = 50% correct; mean = 71.0% correct). Tone production performance ranged from 19.4 to 97.2% correct (mean = 52.0% correct). A strong correlation was found between tone perception and production performance in this group of subjects (r = 0.805).

Cochlear implant (CI) recipients' performance of lexical tone identification and consonant recognition can be enhanced by providing greater spectral details.To evaluate the effects of increasing the number of total spectral channels on the lexical tone identification and consonant recognition by normally hearing listeners who are native speakers of Mandarin Chinese.Lexical tone identification and consonant recognition were measured in 15 Mandarin-speaking, normal-hearing (NH) listeners with varied numbers of total spectral channels (i.e. 4, 6, 8, 10, 12, 16, 20, and 24), using acoustic simulations of CIs.The group of NH listeners' performance of lexical tone identification ranged from 44.53% to 66.60% with 4-24 spectral channels. The performance of tone identification between channels 4 and 16 remained similar; between channels 16 and 20 performance improved significantly. As regards consonant recognition, the NH listeners' overall accuracy ranged from 73.17% to 95.33% with 4-24 channels. Steady improvement in consonant recognition accuracy was observed as a function of increasing the spectral channels. With about 12-16 spectral channels, the NH listeners' overall accuracy in consonant recognition began to be comparable to their accuracy with the unprocessed stimuli.

Frequency allocation with extended frequency ranges yielded significantly higher accuracy in pediatric CI recipients' lexical tone identification. These findings suggest that frequency allocation with extended frequency ranges may be useful in improving lexical tone recognition for at least some pediatric CI recipients.To assess the effects of frequency allocation on lexical tone identification by Mandarin-speaking children with a cochlear implant (CI).In a prospective study, 15 prelingually deafened children between 7.17 and 16.17 years of age served as participants. Using Med-el CI devices, each participant's accuracy in lexical tone identification was compared in two conditions: first, the experimental condition, i.e. use of the extended frequency range from 233 to 8501 Hz; second, the control condition, i.e. use of the participant's clinically assigned frequency range from 300 to 8404 Hz.The group mean of pediatric CI users' accuracy in lexical tone identification was 88.02% (SD = 6.31%) in the experimental condition and 83.82% (SD = 9.84%) in the control condition. The group mean was 4.20% (SD = 5.48%) higher in the experimental condition than that in the control condition; this difference was statistically significant (t(14) = 2.97, p=0.010).

Frequency selectivity represents an important contributory factor in the understanding of human speech. It refers to the ability of the ear to discriminate between two simultaneously occurring sounds of different spectral composition. The capabilities of frequency selection, time pattern analysis, and information processing can be determined generally only by speech audiometry. Schorn and co-workers (1977) published a simplified method for audiological investigations whereby results obtained at two different frequency values are sufficient. The test tone frequencies of 0.5 and 4 kHz were selected because they are representative of the frequency range of normal speech. To determine the influence of ageing on frequency selectivity we investigated three groups of patients between the ages of 20-30, 40-50 and 60-70 years. All of the subjects had normal hearing according to ISO 7029 standards. The measurements of pure-tone audiometry, speech audiometry, and the psychoacoustic tuning curves were performed sequentially on the same day. The influence of ageing on frequency selectivity mainly concerns frequencies above 2 kHz. This is related to the progressive loss of outer hair cells in the basal parts of the cochlea in old age. Our investigations show that particular attention must be paid to a loss of frequency selectivity in old age. This becomes evident mainly after the 60th year. Frequency selectivity is not significantly disturbed before that age, although pure tone audiograms show high frequency inner ear hearing loss earlier in life.

Absolute pitch (AP) is the ability to name a note without any reference, while relative pitch (RP) needs a previous and known tone to recognize such a note. We suggest that AP is due both to environmental impact and physiological particularity. From the responses of 263 musicians including 169 AP we observed that for AP musical environment in childhood was better, the earlier the age of instrumental beginning as compared to RP. The study of otoacustic emissions evoked by a supraliminar stimulation in 183 musicians' ears including 68 AP showed that the echo was significantly greater in cases of AP than in cases of RP.

A group of profoundly hearing-impaired adults is being studied in order to determine their residual auditory capabilities. Most tests use acoustic contrasts that have relevance for the perception of speech, so that the results obtained may be used to guide the development of appropriate hearing aids. All the listeners are postlingually deafened, with losses greater than 95 dB HL at and above 500 Hz, and least loss at low frequencies. Trends in detection thresholds, discomfort levels, dynamic ranges, intensity discrimination (both static and dynamic), frequency selectivity, spectral shape discrimination, gap detection, tone/noise discrimination, frequency discrimination and phase sensitivity are reported and discussed. Generally speaking, temporal resolving power seems to be more resistant to degradation than mechanisms of frequency selectivity. Furthermore, at least some of the differences in performance between normal and profoundly-impaired listeners may be attributable to the loss of frequency selectivity. Implications are drawn for hearing aid fitting and design, and comparisons made to the electro-auditory abilities of users of single-channel cochlear implants.

To evaluate the effect of ipsilateral and contralateral low-frequency (250 Hz) narrow-band noise (NBN) on the temporary threshold shift (TTS) induced by a 2 kHz tone in young normally hearing subjects with a functioning auditory efferent system.Sixteen young volunteers served as subjects. All the subjects were young (20-30 years), disease-free and had a medical history negative for otological disease, noise exposure and use of ototoxic drugs. They had normal hearing [thresholds of 125-8,000 Hz below 20 dB hearing level (HL)], transient-evoked otoacoustic emissions and contralateral suppression. The subjects were randomly assigned to one of three different groups. Subjects in Group A (n = 5) were exposed to a 90 dB HL 2 kHz pure tone for 10 min. Subjects in Group B (n = 6) were exposed to a 90 dB HL 2 kHz pure tone and an ipsilateral 45 dB HL 250 Hz NBN for 10 min. Subjects in Group C (n = 5) were exposed to a 90 dB HL 2 kHz pure tone and a contralateral 45 dB HL 250 Hz NBN for 10 min. The right ear served as the test ear. The TTS 2 min after the end of the exposure (TTS2) was measured in all subjects at 2, 3 and 4 kHz.TTS, in Group A was significantly higher at 3 kHz (p = 0.011) and at 4 kHz (p = 0.003) than TTS2 in Group B. At 4 kHz, TTS2 in Group C was significantly higher (p = 0.013) than TTS2 in Group B. Although TTS2 in Group C was lower than TTS2 in Group A, this difference was not significant. The presence of an ipsilateral low-frequency NBN significantly reduced TTS2 induced by a 90 dB HL 2 kHz tone. A contralateral low-frequency NBN reduced TTS2 in this group of subjects; however, the reduction was not significant.The results of this study show that an ipsilateral low-intensity, low-frequency (250 Hz) NBN can give protection from a TTS induced by a 2 kHz tone. Contralateral low-frequency NBN did not induce any protective effect.

The hypothesis that temporal code is mainly responsible for speech recognition is discussed. Data from cochlear implant research demonstrate that single-channel speech processors, supplying only temporal code, enable understanding of spoken language. Physiological findings supporting the observation are presented. A temporal theory of tone pitch perception is discussed.

This study was designed to evaluate the effects of gender and probe frequency on the ipsilateral click-evoked acoustic reflex thresholds. Ipsilateral acoustic reflex thresholds were obtained from the left ear of each subject (12 male and 12 female normal young adults) by presenting clicks at the rate of 180/sec. The probe tone frequencies were 226, 678 and 1.000 Hz. The results revealed that acoustic reflex thresholds for the 678 Hz probe were significantly higher than those obtained with the 226 and 1.000 Hz probes. No gender differences were apparent. However, the static admittance was significantly correlated with the acoustic reflex thresholds for the 678 Hz probe in only the female subjects. For the 226 Hz probe, the elicitation of the reflex resulted in a decrease in static admittance in all the subjects. For the 678 Hz probe, the admittance decreased in 58% of the subjects and it increased in 42% of the subjects. For the 1,000 Hz probe, an increase in admittance was apparent in all of the subjects. The results suggest that either the 226 Hz or the 1,000 Hz probes can be used for the measurement of click-evoked acoustic reflex thresholds in adults.

The cochlear implant program in Budapest began in 1985, since when 60 operations have been performed, 14 of them on children (51 primary procedures and 9 reimplantations). Different devices and also different techniques have been used: extracochlear promontory, extracochlear round window and intracochlear implants. Various speech processors were applied; at first a digital pulsatile sound-encoding system, later on analog processors were used, while processors operating on the basis of the CIS strategy are preferred nowadays. The operations were performed on both pre- and postlingual patients. In several cases contralateral hearing improvement was observed 6 months after the operation. Considerable experience has been gained of unique cases, such as a deaf-blind prelingual child and prelingual twins. Evaluating cochlear implant performance, in addition to the usual audiological tests measuring postoperative speech understanding, warble tone sound field thresholds were also established.

Experimental animals (cats) were exposed to tones of 125, 1000, 2000, and 4000 Hz at sound pressure levels in the range 120 to 157.5 dB, and for durations of one hour (1000, 2000, 4000 Hz) or four hours (125 Hz). Pure tone audiograms were obtained for each animal before and after exposure. Post-exposure tests were continued until complete recovery of hearing had occurred or until a stable permanent threshold shift had been measured. Cochleas of animals were examined by phase-contrast microscopy; condition of all hair cells was recorded. Extent of inner-ear damage and range of frequencies for which hearing loss occurred increased as exposure tone was decreased in frequency. For example, exposure to 4000 Hz produced damage in a restricted region of the cochlea and hearing loss for a relatively narrow range of frequencies; exposure to 125 Hz produced wide-spread inner ear damage and hearing loss throughout the frequency range 125 to 6000 Hz.

In humans, a partially implantable middle ear implant (MEI) will first be applied, followed by a wholly implantable MEI, since with the former only an induction coil and a vibrator (to the stapes' head) are used. One of the various advantages of the partially implantable MEI vis-à-vis air conduction hearing aids is that the tone quality is of much higher fidelity, with less noise.

Bone-conduction measurements are inaccurate and often troubled by masking problems. Determination of the temporal integration of acoustic energy by Brief Tone Audiometry permits an estimate of the cochlear threshold. In 71 patients with middle ear pathology, the conductive impairment was measured using both conventional audiometry and Brief Tone Audiometry. In 85% of the patients, the estimates coincided within 15 dB. Results from pre- and post-operative measurements are given, and it is demonstrated that Brief Tone Audiometry can be used as an alternative to bone-conduction audiometry to determine the degree of conductive loss with the same accuracy, but without the latter's limitations.

Two main parameters of stimulation were checked as an attempt to investigate the limits of the tonotopic organization in the human auditory cortex. Auditory Evoked magnetic Field (AEF) experiments from a dozen normal subjects are reported. Five of them clearly showed tonotopic AEF responses to long tone bursts stimuli, which disappeared when equivalent white noise was superimposed to the tone. Discrepancies from previous reports and high inter-individual variability are discussed.

A battery of psychophysic tests has been designed through a computerized command of the patient's emitter. Because of the fatigability of these implanted patients, especially in the case of deaf-mute children, and the tedious aspect of these exams only 4 tests are commonly used: the threshold level in a Bekesy way, the tone decay test, the 2 channels discrimination at different intensity levels, the lowest intensity discrimination. If the electrode impedances have been per-operatively measured, these tests are useful to understand the particular phonemic discrimination difficulties of each patient.

In order to avoid false and quantitatively unprecise responses the stimulating electrode must be directly placed on the round window membrane. That necessitates a transmeatal approach removing the eardrum, which is commonly achieved under local anesthesia. The positive response is subjectively easy to identify; it may be objectively registered by means of brain stem evoked responses; this registration is indispensable in case of children who need general anesthesia. This positive response signifies that some cochlear nerve fibers are still present, and therefore that the rehabilitation of the cochlear implant is possible. Among the 460 totally deaf, stimulated patients, more than 93% of them presented a positive response. The threshold level voltage value represents a statistically significant representation of the functional value of the electrode nerve interface. The features of the tone decay tests, which may be also subjectively or objectively performed, present important data which may be used to predict the clinical results that can be obtained by the cochlear implant.

Using the technique of manual adaptation test, recordings of perstimulatory changes at threshold were made during a 3-min. stimulation period on 300 patients, suffering mainly of perception deafness. Results are reported of the magnitude of the perstimulatory threshold shift at various frequencies, of the relation of this shift to recruitment phenomenon, and of the frequency of cases with extreme tone decay in various diagnostic groups.

Based upon the work of Lane (1925) and Lehnhardt (1961), the phenomenon of binaural beats was further studied. The behaviour of the beats as a function of frequency points to three distinctly different frequency regions with an optimum audibility in the range from 90 to 800 cps, less clear from 850 to 1100 cps, audibility falling rapidly beyond 1100 to 1400 cps, disappearance at 1500 cps. In the optimum range the loudness modulation of binaural beats is comparable to that of a monaural, about 2 db modulated tone. Binaural beats are detectable at levels of 20 db below threshold in one ear, if the level in the other ear is above or near threshold.

Studies on perstimulatory threshold adaptation were made in 41 presbyacutic ears with a Grason-Stadler model E 800 Btetey-audiometer using both interrupted and continuous test tones. No adaptation appeared when 200 msec pulsed tones were used. With continuous tones adaptation after 3 min was always less than 10 dB at 250 and 500 Hz. At 1,000 Hz adaptation between 10–30 dB was found in 8%, at 2,000 Hz in 25% and at 4,000 Hz in 2976. During the stimulation, the excursion amplitude remained unchanged with a pulsed tone and with continuous tone there was diminution in size at 4,000 Hz only.

A preliminary report of the effect of high-intensity noise on cochlear hair cells. The animals have been exposed to various kinds of noise from two different tone generators, jet engines, helicopters, gun shots and white noise. The structural changes appearing inside the organ of Corti are described.

A new test has been used as a clinical aid in the topical diagnosis of impaired hearing.A pure tone (2000 cps) was presented at threshold for 90 seconds unless it faded away before that time. In the latter case the intensity was increased by 5 db. The procedure was repeated until the tone was heard at one level for 90 seconds.In normal individuals, the maximum tone decay was 10 db. In pure conductive hearing loss, the values were as in normal individuals. In cochlear deafness a more pronounced tone decay was measured in some cases; in others the test was normal. Excessive “relapse” was found only in retrocochlear deafness.Pronounced threshold tone decay is considered to be indicative of functional impairment of the central auditory pathways or the acoustic nerve.

Single unit study of the cochlear nucleus complex in the mouse was performed. Two types of units were encountered which differed in their tuning curves, their threshold excitability and their response to increasing sound stimulation. The findings suggest that a type I unit conveys information concerning the frequency of a tone and the type II unit the intensity of the stimulating sound. Inhibition with two tone interaction was shown to exist in type I units. Attempts were made to determine the mode of inhibition in peripheral auditory units. Inhibitory interbeat tracking by units indicates a neural mechanism for the inhibition encountered in peripheral auditory units seen during two tone interaction.

As far as the tone decay test may be used to demonstrate the existence of pathological fatigue, it is possible to show that such fatigue may be present only in restricted frequency ranges. The topological anatomy of the eighth nerve seems to indicate in which fibers such pathological fatigue is most likely to occur. This conception is in good agreement with the positive findings of pathological tone decay in certain frequency ranges, together with normal conditions for other tones.

The hearing loss in otosclerosis follows certain fairly typical lines. At the early stage the loss is often greatest at the low frequencies. According to the impedance formula of Johansen, this is due to stiffness of the ossicular chain. Later, when the stapes footplate has become fixed to the oval window, the audiograms show mass flattening; hearing now deteriorates also in the high-frequency range, the final result being a more or less even impairment throughout the auditory range. Yet, as we all know, audiograms indicating greater hearing loss in the high than in the low range are not infrequent in patients with otosclerosis. The air-bone gap—always great in these cases at the low frequencies—is reduced towards the high frequencies, and in some cases the air and bone audiograms may even unite. This results in a curve of mixed deafness type, attributed to a cochlear involvement complicating a purely conductive lesion.

The Zwislocki acoustic bridge was used to study the acoustic stapedius reflex in 30 normal young adults. The stimuli were bursts of white noise, narrow bands of noise centered at 2 000 and 4 000 Hz, and pure tones of 250, 2 000 and 4 000 Hz. An electroacoustic data recording system was substituted for the aural monitoring system that is normally used with the Zwislocki bridge; the sensitivity of the system was such that it allowed identification of one to two decibel changes in the probe tone level. The mean threshold values for the pure tones studied were 81 dB SL, while the means associated with the several noise stimuli were 62 dB SL. The thresholds for the noise stimuli were found to be significantly more stable than those for pure tones.

A method is described for the quantitative performance of the test of Gelle, the tone threshold for air- as well as bone-conduction as a function of air-pressure in the auditory canal being determined by amplitude modulation. Special attention is paid to the influence of the occlusion effect and the necessity for masking in bone-conduction measurements.The author has tried to determine the range in which the results may vary, for normals as well as for patients with otosclerosis. In agreement with many other investigators, it has been found that in cases of stapedial ankylosis the bone-conduction threshold is not affected by air-pressure changes in the auditory canal. An attempt is made to explain this phenomenon.

(1964). Measurement Of Tone Response By The Human Foetus: A preliminary report. Acta Oto-Laryngologica: Vol. 57, No. 1-2, pp. 188-192.

A survey has been made of different special procedures in speech audiometry which are based on creating difficulties for the correct perception and comprehension of speech and the elements which constitute it. According to the procedure followed, a modification or distortion (sensibility) may take place of: 1°, One of the qualities of the voice (pitch, intensity or tone quality) in speech function; 2°, One of the rhythmic qualities of the word and speech (acceleration of the words or phrases, interruption in the word, inversion of the phrases, translation of the accents); 3°, One of the superior qualities—mnesic, of attention and semantic—of language (phrases or lists of words of different amplitude, lists of difficult words, meaningless phrases, alternated phrases, different simultaneous speeches). These recent procedures in speech audiometry constitute a new chapter promising in range, principally for the topographical diagnosis of central lesions (which, as we have seen, could not be carried out throug...

The authors examined reaction of rhythm of the fetus heart in 32 pregnant women in the last month of pregnancy, after tone giving of 1000 and 2000 c/s and of intensity 100 db for 5 sec. The pulses of the mother and fetus were registered by Hellige's phonocardiograph before, during and after tone giving.Acceleration of fetus heart was observed in the group tested 1000 c/s average 7 beats a minute, in the group tested 2000 c/s 11 beats a minute. The mother's pulse did not show any acceleration during the tone or later on.

During continuous tone stimulation a gradual decrease of the provoked impedance change in the normal human ear occurs. The reactivation from this reflex fatigability when superimposing a second tone is studied by means of an electroacoustic impedance bridge. The assumption that the reactivation implies a frequency difference between the two tones is not confirmed in our investigations.

In guinea pigs cochlear microphonic responses were studied during stimulation with harmonic high tone complexes. In the apical portion of the cochlea a sine wave with the frequency of the “missing fundamental” could be recorded. The amplitude of this low frequency microphonic potential (CM) in the third turn of the cochlea appears to be about equal to the amplitude of the strongest component of the high tone complex recorded in the basal turn. The “missing fundamental” appears to stimulate the apical portion of the cochlea, which indicates cochlear analysis according to a certain place principle, although apparently not the Fourier principle.

A Grason—Stadler E800 Bekesy audiometer was used for threshold measurements with sweep—frequency technique starting from the low tones (forward) and then from the high frequencies (reverse). The tracings were superimposed for both interrupted and continuous tones in normal—hearing subjects and in cochlear deafness. In some cases, most frequently in retro—cochlear lesions, the reverse tracing was poorer than the forward curve for continuous tones in the middle—and/or high—frequency regions. This behaviour was associated with pronounced threshold tone decay and, almost without any exceptions, with negative or incomplete recruitment.

Analysis of the sweep frequency audiograms of the 58 affected members tested revealed a characteristic pattern of progression of hearing deterioration in the family under observation. Five stages of impairment, viz. A-E and their intermediate phases, could be distinguished. It was observed that at first only the high frequencies above about 1000 Hz deteriorate. This occurs in two phases, first up to 60 dB, and then up to 80 dB. Thereafter hearing in the low frequency region deteriorates similarly while the high tone loss remains almost constant. It is suggested that this separate, and successive, impairment of high and low frequency hearing might be explained by the existence of a high and a low frequency system in the cochlea, as recently established in various investigations. The two-step progression of hearing loss could be explained by the difference in excitability between outer and inner hair-cells as observed experimentally. It is assumed that the outer haircells degenerate first, resulting in a 60...

In a group of 30 MS patients a normal peripheral hearing was measured (tone audiogram, speech threshold and discrimination ability), but pathological finding in about 50 per cents in both BRA and a filtered speech test was found. The correlation between these pathological findings was only about 0.5.

Clinical examination, audiometry and impedance measurements were performed on 82 patients after myringoplasty. In the operated ears the mean compliance was 0.41 ml (S.D. 0.31 ml) and the middle ear pressure –8.1 mm H2O (S.D. 34.2 mm H2O). The respective values of 73 normal ears were 0.53 ml (S.D. 0.26 ml) and 0.0 mm H2O (S.D. 19.4 mm H2O). The tympanogram with 0.22 kHz probe tone was generally V-shaped, although in one case it was flat and in another W-shaped. In the normal ears the curve was always V-shaped. With 0.8 kHz probe tone a W-shaped curve was obtained in 31 of the myringoplasty ears but only in one normal ear. The stapedius reflex was positive in 31 operated ears and almost all of the normal ears. The correlations of tympanometry to both the clinical status and audiometry were good, but those of compliance values were low. Operated ears with a conductive gap often revealed a deep V-shaped curve with the 0.22 kHz probe tone and a W-shaped one with the 0.8 kHz probe tone.

Eleven normal subjects were examined by the impedance method with respect to the influence of probe—tone intensity on the middle ear muscle reflexes. If the probe tone is reduced from 70 dB sensation level to 60 dB SL, the threshold tends to become higher and the reflexes are smaller. This holds for reflex—eliciting stimuli up to around 95—100 dB. With stronger stimuli, the reflexes become stronger with weak probe tones. Thus, exact knowledge about probe—tone intensity is important for accurate evaluation of the middle—ear muscle reflexes by the impedance method.

TTSs produced by short (500-1000 msec) pure frequency (2000, 3000, 4000 c.p.s.) tones on normal young subjects show, under comparable conditions, the same essential characteristics as TTSs which follow longer stimulations. In particular, they show a tendency to a displacement of their maximal values, as soon as the stimulating tone is presented at adequately high (100 dB SPL) intensity levels, towards a frequency about a halfoctave higher than that of the stimulating tone. In our experiments, however, this tendency was more clearly and constantly demonstrable following stimulations with 3000 c.p.s. tones. Significant individual variations in quantitative aspects of the TTSs have been observed. It is suggested that the use of short tones may be easier and more applicable in practice in investigations concerning the after effects of acoustical stimulation and possible also in procedures aimed at obtaining a better understanding of the significance of individual variations in the behaviour of the receptor organ upon exposure to high intensity stimulations.

Decades of medical examinations have shown that large-scale risks of hearing defects exist not only from 90 dB(A) upwards, but even from 85 dB(A) upwards. This experience is confirmed by the analysis of 25 000 tone threshold audiograms and by the results of experimental hearing fatigue tests.ZusammenfassungWie die jahrzehntelange arztliche Begutachtung zeigt, bestehen starkere Horschadigungsrisken nicht erst ab 90, sondern schon ab einem Larmpegel von 85 dB(A). Diese Erfahrung wird durch eine Analyse von 25000 Tonschwellenaudiogrammen und durch das Ergebnis ex-perimenteller Gehoremudungstest bestatigt.

A 500 Hz pure tone is presented binaurally with earphones. The tone is adjusted to give a midline impression at confortable loudness level. An electronic variable time delay line unit and a generator for randomizing the shift of the phase lag of the signal to the right or to the left ear, respectively, are used. By shortening the time delay the threshold of the recognition of the phase difference is reached. At every test sequence the tone is first presented in the center of the head without delay and then with delay. The patient runs the test by indicating in which ear the tone is heard. The phase difference is thus gradually reduced from 500 musec down to a threshold value of about 48 musec equal on right and left ears in normal-hearing subjects. The results of phase audiometry on subjects with normal hearing and with different types of hearing losses are in good agreement with the results of sound localization tests in free field. Phase audiometry seems to be of especial value in diagnosing retrocochlear lesions.