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Objective: To validate a method using self-reported speech communication effort in noise to estimate occupational noise levels by comparing with measured noise levels. Design: A comparative observational study. Reported vocal effort to communicate with a person at a distance of 1.2 m during workplace-related tasks was used to provide an estimate of noise levels in the workplace. These estimated noise levels were compared against noise level measurements obtained using personal noise dosimetry badges for corresponding tasks undertaken by participants. Study sample: Participants ( n  = 168) aged 16-25 years were recruited from companies where workplace noise levels were at least 85 dB(A). Results: Estimated noise levels using speech communication ability were evenly distributed above and below the measured noise levels ( n  = 134), indicating a lack of systematic bias in the method. For 91% of participants, estimates of noise levels using speech communication were within ±6 dB of the measured levels, whilst 56% were within ±3 dB. Conclusions: Report of speech communication effort required in noise by employees is an effective method of estimating noise levels within the workplace. This can be used for retrospective noise level assessment where there are no recorded noise level measurements, such as for retrospective research studies or in medicolegal work.

Objectives: To assess longitudinal outcomes in a large and varied population of children receiving bilateral cochlear implants both simultaneously and sequentially., Methods: This observational non-randomized service evaluation collected localization and speech recognition in noise data from simultaneously and sequentially implanted children at four time points: before bilateral cochlear implants or before the sequential implant, 1 year, 2 years, and 3 years after bilateral implants. No inclusion criteria were applied, so children with additional difficulties, cochleovestibular anomalies, varying educational placements, 23 different home languages, a full range of outcomes and varying device use were included., Results: 1001 children were included: 465 implanted simultaneously and 536 sequentially, representing just over 50% of children receiving bilateral implants in the UK in this period. In simultaneously implanted children the median age at implant was 2.1 years; 7% were implanted at less than 1 year of age. In sequentially implanted children the interval between implants ranged from 0.1 to 14.5 years. Children with simultaneous bilateral implants localized better than those with one implant. On average children receiving a second (sequential) cochlear implant showed improvement in localization and listening in background noise after 1 year of bilateral listening. The interval between sequential implants had no effect on localization improvement although a smaller interval gave more improvement in speech recognition in noise. Children with sequential implants on average were able to use their second device to obtain spatial release from masking after 2 years of bilateral listening. Although ranges were large, bilateral cochlear implants on average offered an improvement in localization and speech perception in noise over unilateral implants., Conclusion: These data represent the diverse population of children with bilateral cochlear implants in the UK from 2010 to 2012. Predictions of outcomes for individual patients are not possible from these data. However, there are no indications to preclude children with long inter-implant interval having the chance of a second cochlear implant.

Objectives: This fourteen-centre project used professional rating scales and parent questionnaires to assess longitudinal outcomes in a large non-selected population of children receiving simultaneous and sequential bilateral cochlear implants., Methods: This was an observational non-randomized service evaluation. Data were collected at four time points: before bilateral cochlear implants or before the sequential implant, one year, two years, and three years after. The measures reported are Categories of Auditory Performance II (CAPII), Speech Intelligibility Rating (SIR), Bilateral Listening Skills Profile (BLSP) and Parent Outcome Profile (POP)., Results: Thousand and one children aged from 8 months to almost 18 years were involved, although there were many missing data. In children receiving simultaneous implants after one, two, and three years respectively, median CAP scores were 4, 5, and 6; median SIR were 1, 2, and 3. Three years after receiving simultaneous bilateral cochlear implants, 61% of children were reported to understand conversation without lip-reading and 66% had intelligible speech if the listener concentrated hard. Auditory performance and speech intelligibility were significantly better in female children than males. Parents of children using sequential implants were generally positive about their child's well-being and behaviour since receiving the second device; those who were less positive about well-being changes also generally reported their children less willing to wear the second device., Conclusion: Data from 78% of paediatric cochlear implant centres in the United Kingdom provide a real-world picture of outcomes of children with bilateral implants in the UK. This large reference data set can be used to identify children in the lower quartile for targeted intervention.

Objectives: Guidelines published in 2000 by the authors are widely used by medical and legal professionals in the UK for diagnosis of noise-induced hearing loss in a medicolegal context. However, they cannot be used for quantification of the noise-induced hearing loss, which is required in most cases. This requirement is addressed., Design: A method is developed here to quantify noise-induced hearing loss, thereby overcoming this shortcoming., Setting: Assessment of noise-induced hearing loss in medicolegal cases., Participants: A consecutive series of 124 cases of noise-induced hearing loss is used for evaluation., Main Outcome Measure: Magnitude of noise-induced hearing loss based on hearing threshold levels averaged over the frequencies 1, 2 and 3 kHz., Results: The rationale of the method, practical application and three worked examples are developed. A simpler short-cut method is developed and shown to be equivalent to the full method in most cases., Conclusions: The method offers a practical approach to quantification of noise-induced hearing loss., (© 2015 John Wiley & Sons Ltd.)

Current cochlear implant (CI) strategies carry speech information via the waveform envelope in frequency subbands. CIs require efficient speech processing to maximize information transfer to the brain, especially in background noise, where the speech envelope is not robust to noise interference. In such conditions, the envelope, after decomposition into frequency bands, may be enhanced by sparse transformations, such as nonnegative matrix factorization (NMF). Here, a novel CI processing algorithm is described, which works by applying NMF to the envelope matrix (envelopogram) of 22 frequency channels in order to improve performance in noisy environments. It is evaluated for speech in eight-talker babble noise. The critical sparsity constraint parameter was first tuned using objective measures and then evaluated with subjective speech perception experiments for both normal hearing and CI subjects. Results from vocoder simulations with 10 normal hearing subjects showed that the algorithm significantly enhances speech intelligibility with the selected sparsity constraints. Results from eight CI subjects showed no significant overall improvement compared with the standard advanced combination encoder algorithm, but a trend toward improvement of word identification of about 10 percentage points at +15 dB signal-to-noise ratio (SNR) was observed in the eight CI subjects. Additionally, a considerable reduction of the spread of speech perception performance from 40% to 93% for advanced combination encoder to 80% to 100% for the suggested NMF coding strategy was observed., (© The Author(s) 2015.)

Objective: Correlating electrical activity within the human brain to movement is essential for developing and refining interventions (e.g. deep brain stimulation (DBS)) to treat central nervous system disorders. It also serves as a basis for next generation brain-machine interfaces (BMIs). This study highlights a new decoding strategy for capturing movement and its corresponding laterality from deep brain local field potentials (LFPs)., Approach: LFPs were recorded with surgically implanted electrodes from the subthalamic nucleus or globus pallidus interna in twelve patients with Parkinson's disease or dystonia during a visually cued finger-clicking task. We introduce a method to extract frequency dependent neural synchronization and inter-hemispheric connectivity features based upon wavelet packet transform (WPT) and Granger causality approaches. A novel weighted sequential feature selection algorithm has been developed to select optimal feature subsets through a feature contribution measure. This is particularly useful when faced with limited trials of high dimensionality data as it enables estimation of feature importance during the decoding process., Main Results: This novel approach was able to accurately and informatively decode movement related behaviours from the recorded LFP activity. An average accuracy of 99.8% was achieved for movement identification, whilst subsequent laterality classification was 81.5%. Feature contribution analysis highlighted stronger contralateral causal driving between the basal ganglia hemispheres compared to ipsilateral driving, with causality measures considerably improving laterality discrimination., Significance: These findings demonstrate optimally selected neural synchronization alongside causality measures related to inter-hemispheric connectivity can provide an effective control signal for augmenting adaptive BMIs. In the case of DBS patients, acquiring such signals requires no additional surgery whilst providing a relatively stable and computationally inexpensive control signal. This has the potential to extend invasive BMI, based on recordings within the motor cortex, by providing additional information from subcortical regions.

Although there are numerous papers describing single-channel noise reduction strategies to improve speech perception in a noisy environment, few studies have comprehensively evaluated the effects of noise reduction algorithms on speech quality for hearing impaired (HI). A model-based sparse coding shrinkage (SCS) algorithm has been developed, and has shown previously (Sang et al., 2014) that it is as competitive as a state-of-the-art Wiener filter approach in speech intelligibility. Here, the analysis is extended to include subjective quality ratings and a method called Interpolated Paired Comparison Rating (IPCR) is adopted to quantitatively link the benefit of speech intelligibility and speech quality. The subjective quality tests are performed through IPCR to efficiently quantify noise reduction effects on speech quality. Objective measures including frequency-weighted segmental signal-to-noise ratio (fwsegSNR), perceptual evaluation of speech quality (PESQ) and hearing aid speech quality index (HASQI) are adopted to predict the noise reduction effects. Results show little difference in speech quality between the SCS and the Wiener filter algorithm but a difference in quality rating between the HI and NH listeners. HI listeners generally gave better quality ratings of noise reduction algorithms than NH listeners. However, SCS reduced the noise more efficiently at the cost of higher distortions that were detected by NH but not by the HI. SCS is a promising candidate for noise reduction algorithms for HI. In general, care needs to be taken when adopting algorithms that were originally developed for NH participants into hearing aid applications. An algorithm that is evaluated negatively with NH might still bring benefits for HI participants., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Previous investigations have shown that components of a tone burst-evoked otoacoustic emission (TBOAE) evoked by a 1 kHz tone burst (TB1) can be suppressed by the simultaneous presence of a 2 kHz tone burst (TB2) or a pair of tone bursts at 2 and 3 kHz (TB2 and TB3 respectively). No previous study has measured this "simultaneous suppression of TBOAEs" for both TB2 alone and TB2 and TB3 from the same ears, so that the effect of the additional presence of TB3 on suppression caused by TB2 is not known. In simple terms, three outcomes are possible; suppression increases, suppression is reduced or suppression is not affected. Comparison of previously reported simultaneous suppression data suggests TB3 causes a reduction in suppression, though it is not clear if this is a genuine effect or simply reflects methodological and ear differences between studies. This issue has implications for previously proposed mechanisms of simultaneous suppression of TBOAEs and the interpretation of clinical data, and is clarified by the present study. Simultaneous suppression of TBOAEs was measured for TB1 and TB2 as well as TB1, TB2 and TB3 at 50, 60 and 70 dB p.e. SPL from nine normal human ears. Results showed no significant difference between mean suppression obtained for the two and three-tone burst combinations, indicating the reduction of suppression inferred from comparison of previous data is likely a result of methodological and ear differences rather than a genuine effect., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Objective: The aim of the present study was to investigate how well the virtual psychophysical measures of spatial hearing from the preliminary auditory profile predict self-reported spatial-hearing abilities., Design: Virtual spatial-hearings tests (conducted unaided, via headphones) and a questionnaire were administered in five centres in Germany, the Netherlands, Sweden, and the UK. Correlations and stepwise linear regression models were calculated among a group of hearing-impaired listeners., Study Sample: Thirty normal-hearing listeners aged 19-39 years, and 72 hearing-impaired listeners aged 22-91 years with a broad range of hearing losses, including asymmetrical and mixed hearing losses., Results: Several significant correlations (between 0.24 and 0.54) were found between results of virtual psychophysical spatial-hearing tests and self-reported localization abilities. Stepwise linear regression analyses showed that the minimum audible angle (MAA) test was a significant predictor for self-reported localization abilities (5% extra explained variance), and the spatial speech reception threshold (SRT) benefit test for self-reported listening to speech in spatial situations (6% extra explained variance)., Conclusions: The MAA test and spatial SRT benefit test are indicative measures of everyday binaural functioning. The binaural SRT benefit test was not found to predict self-reported spatial-hearing abilities.

Tone burst-evoked otoacoustic emission (TBOAE) components measured in response to a 1 kHz tone burst (TB1) are suppressed by the simultaneous presence of an additional tone burst (TB2). This "simultaneous suppression of TBOAEs" has been explained in terms of a mechanism based on local nonlinear interactions between the basilar membrane (BM) travelling waves caused by TB1 and TB2. A test of this local nonlinear interaction (LNI)-based mechanism, as a function of the frequency separation (Δf, expressed in kHz) between TB1 and TB2, has previously been reported by Killan et al. (2012) using a simple mathematical model [Killan et al., Hear. Res. 285, 58-64 (2012)]. The two experiments described in this paper add additional data on the extent to which the LNI-based mechanism can account for simultaneous suppression, by testing two further hypotheses derived from the model predictions. Experiment I tested the hypothesis that TBOAE suppression is directly linked to TBOAE amplitude nonlinearity where ears that exhibit a higher degree of amplitude nonlinearity yield greater suppression than more linear ears, and this relationship varies systematically as a function of Δf. In order to test this hypothesis simultaneous suppression at a range of values of Δf at 60 dB peak-equivalent sound pressure level (p.e. SPL) and TBOAE amplitude nonlinearity from normal human ears was measured. In Experiment II the hypothesis that suppression will also increase progressively as a function of increasing tone burst level was tested by measuring suppression for a range of Δf and tone burst levels at 40, 50, 60 and 70 dB p.e. SPL. The majority of the findings from both experiments provide support for the LNI-based mechanism being primarily responsible for simultaneous suppression. However, some data were inconsistent with this view. Specifically, a breakdown in the relationship between suppression and TBOAE amplitude nonlinearity at Δf = 1 (i.e. when TB2 was reasonably well separated from, and had a higher frequency than TB1) and unexpected level-dependence, most notably at Δf = 1, but also where Δf = -0.5, was observed. Either the LNI model is too simple or an alternative explanation, involving response components generated at basal regions of the basilar membrane, is required to account for these findings., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Although there are numerous single-channel noise reduction strategies to improve speech perception in noise, most of them improve speech quality but do not improve speech intelligibility, in circumstances where the noise and speech have similar frequency spectra. Current exceptions that may improve speech intelligibility are those that require a priori knowledge of the speech or noise statistics, which limits practical application. Hearing impaired (HI) listeners suffer more in speech intelligibility than normal hearing listeners (NH) in the same noisy environment, so developing better single-channel noise reduction algorithms for HI listeners is justified. Our model-based "sparse coding shrinkage" (SCS) algorithm extracts key speech information in noisy speech. We evaluate it by comparison with a state-of-the-art Wiener filtering approach using speech intelligibility tests with NH and HI listeners. The model-based SCS algorithm relies only on statistical signal information without prior information. Results show that the SCS algorithm improves speech intelligibility in stationary noise and is comparable to the Wiener filtering algorithm. Both algorithms improve intelligibility for HI listeners but not for NH listeners. Improvement is less in fluctuating (babble) noise than in stationary noise. Both noise reduction algorithms perform better at higher input signal-to-noise ratios (SNR) where HI listeners can benefit but where NH listeners have already reached ceiling performance. The difference between NH and HI subjects in intelligibility gain depends fundamentally on the input SNR rather than the hearing loss level. We conclude that HI listeners need different signal processing algorithms from NH subjects and that the SCS algorithm offers a promising alternative to Wiener filtering. Performance of all noise reduction algorithms is likely to vary according to extent of hearing loss and algorithms that show little benefit for listeners with moderate hearing loss may be more beneficial for listeners with more severe hearing loss., (Copyright © 2014 Elsevier B.V. All rights reserved.)

One of the putative functions of the medial olivocochlear (MOC) system is to enhance signal detection in noise. The objective of this study was to elucidate the role of the MOC system in speech perception in noise. In normal-hearing human listeners, we examined (1) the association between magnitude of MOC inhibition and speech-in-noise performance, and (2) the association between MOC inhibition and the amount of contralateral acoustic stimulation (CAS)-induced shift in speech-in-noise acuity. MOC reflex measurements in this study considered critical measurement issues overlooked in past work by: recording relatively low-level, linear click-evoked otoacoustic emissions (CEOAEs), adopting 6 dB signal-to-noise ratio (SNR) criteria, and computing normalized CEOAE differences. We found normalized index to be a stable measure of MOC inhibition (mean = 17.21%). MOC inhibition was not related to speech-in-noise performance measured without CAS. However, CAS in a speech-in-noise task caused an SNRSP enhancement (mean = 2.45 dB), and this improvement in speech-in-noise acuity was directly related to their MOC reflex assayed by CEOAEs. Individuals do not necessarily use the available MOC-unmasking characteristic while listening to speech in noise, or do not utilize unmasking to the extent that can be shown by artificial MOC activation. It may be the case that the MOC is not actually used under natural listening conditions and the higher auditory centers recruit MOC-mediated mechanisms only in specific listening conditions-those conditions remain to be investigated.

Objectives: Otoacoustic emissions-based efferent assays are evolving to become a part of auditory diagnostics. The wide range of clinical applications, such as assessment of auditory neuropathy, auditory processing disorders, learning disability, monitoring success in auditory intervention and others illustrate the significance of this measurement. Defining the procedure's test-retest repeatability is of critical importance, to allow for distinction between measurement deviations and true physiological or pathological changes. The purpose of this study was to assess the repeatability of a click-evoked otoacoustic emission-based (CEOAE) test of the medial olivocochlear (MOC) reflex in normal-hearing (NH) adults., Design: Test-retest data were collected from 35 NH young adults in two distinct test sessions separated by 1 to 4 days. CEOAEs were recorded without and with contralateral acoustic stimulation (CAS; 35 dB SL). Three indices of the MOC reflex were computed: CAS-induced (a) absolute changes in CEOAE amplitude, (b) normalized changes in CEOAE amplitude, and (c) changes in CEOAE input-output functions. Repeatability of these indices was assessed by a three-layered approach, which consisted of Bland-Altman plots, coefficient of reliability (Cronbach's α), and analysis of variance., Results: Analyses indicated good repeatability of three CEOAE-based MOC reflex indices. A two-way analysis of variance of the indices demonstrated no significant difference between test and retest. Normalized index showed similar repeatability as other indices. CEOAE signal to noise ratio did not seem to vary between test sessions. Notably, CAS caused a decrease in CEOAE input-output functions slope in a majority of participants (n = 29)., Conclusions: The present study is the first to elucidate the intrasubject variability of absolute and normalized indices of the MOC inhibitory effect. Although the measurements were conducted under realistic conditions resembling the clinical setting, repeatability was generally good in NH adults. For MOC reflex test, the signal to noise ratio of 6 dB for recording CEOAEs seems to be a recommendable criterion when considering practicability and measurement quality in clinical conditions. The present findings exemplify the suitability of CEOAE-based MOC assay as a monitoring tool of medial efferent status over time. The data are intended to assist clinicians and scientists alike in the accurate interpretation of CAS-induced CEOAE changes in the test-retest situation.

Objective: This paper describes the composition and international multi-centre evaluation of a battery of tests termed the preliminary auditory profile. It includes measures of loudness perception, listening effort, speech perception, spectral and temporal resolution, spatial hearing, self-reported disability and handicap, and cognition. Clinical applicability and comparability across different centres are investigated., Design: Headphone tests were conducted in five centres divided over four countries. Effects of test-retest, ear, and centre were investigated. Results for normally-hearing (NH) and hearing-impaired (HI) listeners are presented., Study Sample: Thirty NH listeners aged 19-39 years, and 72 HI listeners aged 22-91 years with a broad range of hearing losses were included., Results: Test-retest reliability was generally good and there were very few right/left ear effects. Results of all tests were comparable across centres for NH listeners after baseline correction to account for necessary differences between test materials. For HI listeners, results were comparable across centres for the language-independent tests., Conclusions: The auditory profile forms a clinical test battery that is applicable in four different languages. Even after baseline correction, differences between test materials have to be taken into account when interpreting results of language-dependent tests in HI listeners.

Background: Hearing loss is common among older adults and has consequences for sufferers, families and society, but there is substantial unmet need for intervention. Screening could expedite intervention and improve outcomes., Methods: We use Markov models to estimate the incremental cost-effectiveness ratio (ICER) of potential screening programmes compared with current provision (GP-referral), from a health service perspective. Alternative options are investigated through scenario analysis. One-way and probabilistic sensitivity analyses are undertaken., Results: All modelled screens are cost-effective and reduce unmet need for hearing aids. The most cost-effective option identified is a one-stage audiometric screen for bilateral hearing loss ≥30 dB hearing level (HL) at age 60, repeated at ages 65 and 70. This option has an ICER of £1461 compared to GP-referral and would mean an additional 15 437 adults benefiting from hearing intervention per 100 000 population aged 60. The cost-effectiveness acceptability curve shows that screening is more cost-effective than GP-referral provided a Quality Adjusted Life Year is valued at £2000 or more., Conclusions: Adult hearing screening would provide a cost-effective way to improve quality of life for older adults. We recommend piloting an audiometric screen offered to all adults age 60, 65 and 70 years to identify bilateral hearing loss of at least 30 dB HL.

Tone burst-evoked otoacoustic emission (TBOAE) components in response to a 1 kHz tone burst are suppressed by the simultaneous presence of tone bursts at higher frequencies. To date, the underlying cause of this "simultaneous suppression" of TBOAEs is unclear. This paper describes a potential mechanism based on local nonlinear interactions between basilar membrane (BM) travelling waves, and tests the extent to which it is able to account for this specific suppression phenomenon. A simple mathematical model based on local nonlinear interactions was developed, and its predictions for a range of tone burst pairs were compared to corresponding TBOAE suppression data recorded from fourteen normally hearing human ears at a level of 60 dB p.e. SPL. Model predictions and mean TBOAE suppression data showed close agreement for all pairs of tone bursts. These results suggest that simultaneous suppression of TBOAEs can be explained solely in terms of the local nonlinear interaction-based mechanism. However, the involvement of other mechanisms, involving components generated at places basal to their characteristic place along the BM, cannot be excluded., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Objective: Established methods for predicting speech recognition in noise require knowledge of clean speech signals, placing limitations on their application. The study evaluates an alternative approach based on characteristics of noisy speech, specifically its sparseness as represented by the statistic kurtosis., Design: Experiments 1 and 2 involved acoustic analysis of vowel-consonant-vowel (VCV) syllables in babble noise, comparing kurtosis, glimpsing areas, and extended speech intelligibility index (ESII) of noisy speech signals with one another and with pre-existing speech recognition scores. Experiment 3 manipulated kurtosis of VCV syllables and investigated effects on speech recognition scores in normal-hearing listeners., Study Sample: Pre-existing speech recognition data for Experiments 1 and 2; seven normal-hearing participants for Experiment 3., Results: Experiments 1 and 2 demonstrated that kurtosis calculated in the time-domain from noisy speech is highly correlated (r > 0.98) with established prediction models: glimpsing and ESII. All three measures predicted speech recognition scores well. The final experiment showed a clear monotonic relationship between speech recognition scores and kurtosis., Conclusions: Speech recognition performance in noise is closely related to the sparseness (kurtosis) of the noisy speech signal, at least for the types of speech and noise used here and for listeners with normal hearing.

Prior to 2009, UK public funding was mainly only available for children to receive unilateral cochlear implants. In 2009, the National Institute for Health and Clinical Excellence (NICE) published guidance for cochlear implantation following their review. According to these guidelines, all suitable children are eligible to have simultaneous bilateral cochlear implants or a sequential bilateral cochlear implant if they had received the first before the guidelines were published. NICE stated that they would review this decision in 2011. In preparation for this review, 13 UK cochlear implant centres formed a consortium, and the decision was made to carry out a multi-centre audit. The audit involves collecting data from simultaneously and sequentially implanted children at three intervals: before bilateral cochlear implants or before the sequential implant, 1 year after bilateral implants, and 2 years after bilateral implants. The measures include localization, speech recognition in quiet and background noise, speech production, listening, vocabulary, parental perception, quality of life, and surgical data including complications. The audit has now passed the 1-year point, and data have been received on more than 400 children. Preliminary results will be available a year later.

Due to individual characteristics such as head size, earmould type, and earmould venting, the directional benefit that an individual will obtain from a hearing aid cannot be predicted from average data. It is therefore desirable to measure real ear directional benefit. This paper demonstrates a method to measure real ear hearing aid directivity based on a general approach to measure the broadband output signal-to-noise ratio of a hearing aid. Errors arising from non-linearity were tested in simulation and found to be low for typical hearing aid compression ratios. Next, the efficacy of the method to estimate directional benefit was demonstrated on KEMAR. Finally the variability of directional benefit was explored in real-ears. Significant differences in signal-to-noise ratio between directional and omnidirectional microphone settings were demonstrated at most azimuths. Articulation-Index-weighted directional benefit varied by more than 7 dB across ears at some azimuths. Such individual variation in directional benefit has implications when fitting hearing aids: it should not be assumed that all users will receive similar directional benefit from the same hearing aid.

The aim of this study, which was performed in the framework of the European project EMFnEAR, was to investigate the potential effects of Universal Mobile Telecommunications System (UMTS, also known as 3G) exposure at a high specific absorption rate (SAR) on the human auditory system. Participants were healthy young adults with no hearing or ear disorders. Auditory function was assessed immediately before and after exposure to radiofrequency (RF) radiation, and only the exposed ear was tested. Tests for the assessment of auditory function were hearing threshold level (HTL), distortion product otoacoustic emissions (DPOAE), contralateral suppression of transiently evoked otoacoustic emission (CAS effect on TEOAE), and auditory evoked potentials (AEP). The exposure consisted of speech at a typical conversational level delivered via an earphone to one ear, plus genuine or sham RF-radiation exposure obtained by an exposure system based on a patch antenna and controlled by software. Results from 73 participants did not show any consistent pattern of effects on the auditory system after a 20-min UMTS exposure at 1947 MHz at a maximum SAR over 1 g of 1.75 W/kg at a position equivalent to the cochlea. Analysis entailed a double-blind comparison of genuine and sham exposure. It is concluded that short-term UMTS exposure at this relatively high SAR does not cause measurable immediate effects on the human auditory system.

Objective: Cochlear implants for children are known to have impact on the lives of recipients and their families in a variety of ways. To obtain a clearer picture of these benefits, we explored the quality of life of 36 Finnish children and their families 2-3 years after unilateral cochlear implantation., Methods: The studied children were, on average 5 years old, and had received their implant at the median age of 2 years:5 months (range 1:6 to 12:3). Most (67%) of the children used speech, eight (22%) used speech and signs, and four (11%) used sign language as their main communication mode. A third of the children had concomitant problems in addition to their profound hearing impairment. A validated closed-set questionnaire "Children with cochlear implants: parental perspectives" (available, e.g., at http://www.earfoundation.org.uk/research/questionnaires.html) was used to find out parents' views and experiences on implantation and explore life after it., Results: Parents were most satisfied with improved/expanded social relations, improved communication (the development of spoken language), general functioning with the help of hearing and improved self-reliance of the child. Benefit of cochlear implantation was also detected with the Categories of Auditory Performance (CAP), which was concordant with views of the parents on the progress of their child in the areas of communication and education. When deciding on implantation, the parents particularly expected auditory information to enhance their child's safety in traffic, joining socially the hearing world, and better employment prospects as adults. Concerning the process of implantation, parents especially valued the know-how and fluent services of the implant centre, positive attitude within the family and information received from other families during the time they were considering the implant decision. Parents also found it important that they have the possibility to influence the communication mode that is used in their child's educational setting., Conclusions: Parents report that cochlear implants affect their children in a wide variety of ways that cannot be summarized by a single scale. A broader descriptive framework is required to capture their experiences adequately.

Objectives: To estimate the distribution of inter-aural sensorineural hearing threshold level differences in the non-noise-exposed adult population of the UK., Setting: A two-stage population study carried out in 1979-1986, initially by postal questionnaire, followed up in a proportion of participants by clinical and audiological examination., Participants: Volunteers (n = 48 313) initially selected at random from the electoral registers of four cities, subsequently selected at random from questionnaire respondents stratified by answers to questions about hearing., Main Outcomes Measure: Inter-aural hearing threshold level differences measured audiometrically, as a function of age and gender., Results: Tables of inter-aural threshold level differences provided as a resource with potential medicolegal, clinical and research applications. Based on the average of the frequencies 0.5, 1, 2 and 4 kHz, approximately 1% of the general UK population aged 18-80 years have an asymmetry of 15 dB or more. The prevalence is greater in older than in younger people., Conclusions: Inter-aural threshold differences greater than attributable to measurement error are not uncommon in the adult population, even after screening for conductive hearing loss and substantial noise exposure. They are typically of unknown origin.

Abstract The European project EMFnEAR was undertaken to assess potential changes in human auditory function after a short-term exposure to radiofrequency (RF) radiation produced by UMTS (Universal Mobile Telecommunication System) mobile phones. Participants were healthy young adults with no hearing or ear disorders. Auditory function was assessed immediately before and after exposure to radiofrequency radiation, and only the exposed ear was tested. Tests for the assessment of auditory function were hearing threshold level (HTL), distortion product otoacoustic emissions (DPOAE), contralateral suppression of transiently evoked otoacoustic emission (CAS effect on TEOAE), and auditory evoked potentials (AEP). The exposure consisted of speech at a typical conversational level delivered via an earphone to one ear, plus genuine or sham RF-radiation exposure produced by a commercial phone controlled by a personal computer. Results from 134 participants did not show any consistent pattern of effects on the auditory system after a 20-min UMTS exposure at the maximum output of the phone with 69 mW/kg SAR in the cochlea region in a double blind comparison of genuine and sham exposure. An isolated effect on the hearing threshold at high frequencies was identified, but this was statistically nonsignificant after correction for multiple comparisons. It is concluded that UMTS short-term exposure at the maximum output of consumer mobile phones does not cause measurable immediate effects on the human auditory system.

A prototype self-report measure of vestibular rehabilitation outcome is described in a previous paper. The objectives of the present work were to identify the most useful items and assess their psychometric properties. Stage 1: One hundred fifty-five participants completed a prototype 36-item Vestibular Rehabilitation Benefit Questionnaire (VRBQ). Statistical analysis demonstrated its subscale structure and identified redundant items. Stage 2: One hundred twenty-four participants completed a refined 22-item VRBQ and three established questionnaires (Dizziness Handicap Inventory, DHI; Vertigo Symptom Scale short form, VSS-sf; Medical Outcomes Study short form 36, SF-36) in a longitudinal study. Statistical analysis revealed four internally consistent subscales of the VRBQ: Dizziness, Anxiety, Motion-Provoked Dizziness, and Quality of Life. Correlations with the DHI, VSS-sf, and SF-36 support the validity of the VRBQ, and effect size estimates suggest that the VRBQ is more responsive than comparable questionnaires. Twenty participants completed the VRBQ twice in a 24-hour period, indicating excellent test-retest reliability. The VRBQ appears to be a concise and psychometrically robust questionnaire that addresses the main aspects of dizziness impact.

Research suggests that Vestibular Rehabilitation (VR) is an effective treatment for dizziness, but there is currently no measure specifically designed to assess treatment outcome. A review of existing self-report measures of dizziness indicates that no measure has been designed for longitudinal application and all suffer from limitations which restrict their usefulness in measuring VR outcome. A need for a psychometrically robust patient-oriented measure of quality of life benefit from VR is identified. The aim of the present study was to explore dimensions relevant to VR with a view to developing a measure of outcome. Eighteen adults receiving VR participated in interviews about the quality of life impact of dizziness. Qualitative analysis revealed 64 themes describing self-perceived quality of life impact. Themes were developed into potential questionnaire items and 35 were selected to represent the quality of life impact of dizziness in a prototype questionnaire. A quarter of items in the prototype questionnaire refer to issues not addressed by existing measures; the remaining items draw together issues covered by the range of questionnaires currently in use.

We performed a retrospective analysis of TEOAEs from 1415 neonatal ears to investigate whether the application of linear averaging techniques may provide greater screening specificity than conventional nonlinear averaging techniques. Pass criteria were based on correlations between replicate averages, and pass rates were compared between linear and nonlinear averaging techniques. The linear averaging technique gave a higher pass rate as hypothesized, so that 35% of ears that passed using the linear method failed using the nonlinear method. In addition, lack of saturation was more evident for the short-latency components of the TEOAE. These results, from a large sample of recordings obtained under field conditions, indicate that there is potential to improve specificity of neonatal TEOAE screening using linear averaging techniques. A combination of linear and nonlinear techniques for the long and short latency components of the TEOAE, respectively, may offer further advantages.

The European multicenter project named GUARD involved nine centers and aimed to assess potential changes in auditory function as a consequence of exposure to low-intensity electromagnetic fields (EMFs) produced by GSM cellular phones. Participants were healthy young adults without any evidence of hearing or ear disorders. Auditory function was assessed immediately before and after exposure to EMFs, and only the exposed ear was tested. The procedure was conducted twice in a double blinded design, once with a genuine EMF exposure and once with a sham exposure (at least 24 h apart). Tests for assessment of auditory function were hearing threshold level (HTL), transient otoacoustic emissions (TEOAE), distortion product otoacoustic emissions (DPOAE), and auditory brainstem response (ABR). The exposure consisted of speech at a typical conversational level delivered via an earphone to one ear, plus genuine or sham EMF exposure. The EMF exposure used the output of a software-controlled consumer cellular phone at full power for 10 min. A system of phone positioning that allowed participants to freely move their heads without affecting exposure was used. Analysis of the data showed there were no effects of exposure to GSM mobile phone signals on the main measures of the status of the auditory system.

This study investigated learning, in normal-hearing adults, associated with training (i.e. repeated practice) on the discrimination of ongoing interaural time difference (ITD). Specifically, the study addressed an apparent disparity in the conclusions of previous studies, which reported training-induced learning at high frequencies but not at low frequencies. Twenty normal-hearing adults were trained with either low- or high-frequency stimuli, associated with comparable asymptotic thresholds, or served as untrained controls. Overall, trained listeners learnt more than controls and over multiple sessions. The magnitudes and time-courses of learning with the low- and high-frequency stimuli were similar. While this is inconsistent with the conclusion of a previous study with low-frequency ITD, this previous conclusion may not be justified by the results reported. Generalization of learning across frequency was found, although more detailed investigations of stimulus-specific learning are warranted. Overall, the results are consistent with the notion that ongoing ITD processing is functionally uniform across frequency. These results may have implications for clinical populations, such as users of bilateral cochlear implants.

Mobile phones have become very commonly used worldwide within a short period of time. To date there is only limited knowledge about interaction between electromagnetic fields (EMFs) emitted by mobile phones and the auditory function. Moreover, there is widespread concern that there may be potential for harm. The aim of this study was to assess potential subtle changes in cochlear function by measuring the temporal and spectral fine structure of transiently evoked otoacoustic emissions (TEOAE) in normal hearing subjects after exposure to EMFs emitted by Global System for Mobile Communication (GSM) mobile phones. TEOAEs were recorded in 27 healthy young adults before and after 10 min of real or sham exposure in a double-blind design. TEOAE data were analyzed both globally (broadband analysis) and using the Wavelet Transform (analysis of the time-frequency fine structure). The broadband analysis revealed no significant effect on TEOAEs related to exposure, confirming results of previous studies; in addition, no significant change was detected in the analysis of the elementary wavelet components, suggesting that the temporal and spectral fine structure of TEOAEs is not affected by 10 min exposure to low-intensity EMFs emitted by GSM mobile phones.

Background: Preverbal vocal and auditory skills are essential precursors of spoken language development and they have been shown previously to predict later speech perception and production outcomes in young implanted deaf children., Objectives: To assess the effect of age at implantation on the development of vocal and auditory preverbal skills in implanted children., Methods: The study assessed 99 children, 33 in each of three groups (those implanted between 1 and 2 years; 2 and 3 years; and 3 and 4 years). Preverbal skills were measured in three areas: turn taking, autonomy and auditory awareness of spoken language, using the Tait video analysis method., Results: The youngest implanted group made an exceptional progress outperforming in all measures the two other groups (p<0.01), 6 and 12 months post-implantation, whereas there was no such difference before implantation. In the youngest group there was also significantly greater use of an auditory/oral style of communication: 85% of the group by 12 months post-implantation compared with 30% and 18% of the two older groups., Conclusions: Vocal and auditory preverbal skills develop much more rapidly in children implanted between 1 and 2 years in comparison with older implanted children and reach a significantly higher level by 6 and 12 months post-implantation. In addition, younger implanted children are significantly more likely by 12 months post-implantation to adopt an auditory/oral mode of communication. These findings favour cochlear implantation as early as between 1 and 2 years, provided that correct diagnosis and adequate hearing-aid trial have been achieved.

Mobile phone ownership and usage is now widespread and public concern has developed over possible harmful physiological effects of their use. This study aimed to investigate the prevalence of student mobile phone ownership and any possible chronic effects of usage on hearing, tinnitus and balance. Questionnaires for electronic self-completion were distributed to University of Southampton postgraduates, and 117 out of 160 returned met the criteria for analysis. A total of 94% were current mobile phone users, and only 2% had never used a mobile phone. Duration of ownership and daily usage ranged from 0-7 years and 0-45 minutes respectively. Text-messaging was more popular than talking. High or long-term users reported no worse hearing, tinnitus, or balance than low or short-term users. The results of this study confirm that the prevalence of mobile phone ownership amongst students is extremely high. However there appear to be no harmful effects of mobile phone usage on their audiovestibular systems within the range of exposure of the study, insofar as can be detected by the self-report method employed.

The 2f1-f2 distortion product otoacoustic emission (DPOAE) is considered to consist of two components in normally hearing ears, one having constant phase with changing DP frequency (wave fixed) and one having an increasing phase lag with increasing frequency (place fixed). The aim was to identify the wave-fixed and place-fixed components of both 2f1-f2 and 2f2-f1 DPs, and, in particular, to show whether a wave-fixed 2f2-f1 DP exists in normally hearing adults. DPOAE recordings were made in 20 ears of normally hearing young adults. Four frequency ratios were used and recording entailed fixed frequency-ratio sweeps. A separation into wave-fixed and place-fixed components was carried out using a time-window separation method. A method for estimating the noise floor after data processing was developed. Results confirmed the presence of wave-fixed and place-fixed components for 2f1-f2, consistent with previous studies. Both components were also present for 2f2-f1 in virtually all subjects. This latter finding conflicts with current models of DPOAE generation, and so a modified model is proposed. Unlike the 2f1-f2 emission, which has a wave-fixed component that is strongly dependent on the frequency ratio, neither component of the 2f2-f1 emission showed such a dependence. The proposed model explains these findings in terms of the overlap of the primary frequency traveling waves.

The advent of bilateral cochlear implants (CIs) has increased interest in learning on binaural tasks, and studies in normal-hearing listeners provide important background information. However, few studies have considered learning with discrimination of interaural time difference (ITD). Here, learning with ITD was explored using stimuli that are more relevant to bilateral CIs than used previously. Inexperienced listeners were trained with envelope-based ITD using high-frequency amplitude-modulated tones with or without an interaural carrier frequency difference (IFD), the former to simulate asymmetrical bilateral CI insertions. All were tested with and without IFD before and after training. In most listeners, ITD thresholds improved substantially with training, not necessarily reaching asymptote after 3,000 trials. In these, the magnitude and time-course of learning was larger than anticipated from a previous study with low-frequency ITD. Learning generalized across IFD and the effect of IFD on ITD thresholds at post-test was smaller than reported previously. These results have implications for studies of bilateral CIs, such as the need to provide extensive training to avoid over-estimating any apparent 'impairment'.

The auditory evoked potential known as the middle latency response (MLR), evoked with regular click stimulation at around 5 Hz, has been suggested as an indicator of adequacy of anesthesia. The MLR is a very small signal embedded in high levels of background noise, so it can take a long time to acquire. However, using a stimulus paradigm of chirps presented in a maximum length sequence, the acquisition of the MLR can be improved compared to using conventional click stimulation. In this pilot study, we investigated this new technique in a clinical environment. Significant changes in MLR amplitude, but not latency, were measured for six of seven subjects in association with changes in responsiveness to command using the isolated forearm technique. The absence of any latency shift differs from other studies of the MLR during anesthesia and highlights the limited understanding of the relationship between anesthesia and the MLR.

The 2F1-F2 distortion product otoacoustic emission (DPOAE) is considered to consist of two generation mechanisms, the so-called place-fixed and wave-fixed mechanisms, depending on the frequency ratio F2/F1. The general assumption is that for a small frequency ratio there is a predominantly place-fixed emission mechanism, while with a larger frequency ratio there is a predominantly wave-fixed mechanism. There is also a lack of published data on the repeatability of the two components when separated. One aim of this study was therefore to identify the wave-fixed and place-fixed components of the 2F1-F2 DPOAE using a time-window separation method. The second aim was to quantify the test-retest repeatability of the separated 2F1-F2 DPOAE components in a group of normally hearing subjects. Results confirmed the presence of wave-fixed and place-fixed components for 2F1-F2 and a predominance of place or wave-fixed DPOAE as a function of frequency ratio. This pattern varied somewhat among subjects. Moreover, regardless of which component was stronger for any F2/F1, both components were highly repeatable across time within individual ears.

Methodology is proposed for perceptual assessment of both subjective sound quality and speech recognition in such way that results can be compared between these two aspects. Validation is performed with a noise suppression system applied to hearing instruments. A method termed Interpolated Paired Comparison Rating (IPCR) was developed for time efficient assessment of subjective impression of different aspects of sound quality for a variety of noise conditions. The method is based on paired comparisons between processed and unprocessed stimuli, and the results are expressed as the difference in signal-to-noise ratio (dB) between these that give equal subjective impression. For tests of speech recognition in noise, validated adaptive test methods can be used that give results in terms of speech-to-noise ratio. The methodology was shown to be sensitive enough to detect significant mean differences between processed and unprocessed speech in noise, both regarding subjective sound quality and speech recognition ability in groups consisting of 30 subjects. An effect on sound quality from the noise suppression equivalent to about 3-4 dB is required to be statistically significant for a single subject. A corresponding effect of 3-6 dB is required for speech recognition (one-sided test). The magnitude of difference that occurred in the present study for sound quality was sufficient to show significant differences for sound quality within individuals, but this was not the case for speech recognition.

Closed-set word tests can be implemented with or without trial-by-trial visual feedback. Feedback is considered to increase subject motivation yet its influence on performance is unknown. The aim of this study was to compare performance on the Four Alternative Auditory Feature (FAAF) test with and without visual feedback over a 24-week period following fitting of a hearing aid. A total of 32 elderly subjects were recruited as new users and fitted monaurally with the same model of linear, programmable hearing aid that provided in excess of 20 dB insertion gain at 2-4 kHz. Half of the subjects were provided with visual feedback. In these subjects, mean performance increased by 5% across the study period. The improvement in performance over time was statistically significant on analysis of variance (p < 0.05). Mean performance did not increase in the remaining subjects who were not provided with feedback. If closed-set word tests are to be used with visual feedback to measure changes over time, the potentially confounding effects of practice must be controlled carefully. Alternatively, omitting feedback leads to simpler experimental designs.