The hearing health of live-music sound engineers.

Most studies of hearing loss prevention in the music industry focus on the risk of hearing injury to musicians. However, live-music sound engineers (LMSE) may also be at risk of hearing injury due to their work-related sound exposure. We studied 27 LMSE, all of whom underwent otologic examination, including audiometry, distortion product otoacoustic emissions, speech discrimination and uncomfortable loudness levels, and completed a questionnaire investigating their history of sound exposure and use of hearing protectors. Hearing thresholds were significantly poorer than normative data across several frequencies, and a substantial proportion reported constant tinnitus (30%) and reduced sound tolerance (41%). Use of hearing protection was relatively low, with many reporting interference with their job when using it. Our results suggest that LMSE are at risk of hearing injury due to their work-related sound exposure.

Speech Perception Outcomes for Adult Cochlear Implant Recipients Using a Lateral Wall or Perimodiolar Array.

AIM: To assess the speech perception outcomes of adult CI recipients with significant preimplant low frequency hearing, examining differences between perimodiolar and lateral wall electrode placement in order to provide clinical guidance for clinicians and surgeons. METHODS: A prospective cohort study was undertaken identifying all adults who received a thin straight electrode array (TSEA) at the Royal Victorian Eye & Ear Hospital (RVEEH) from 2010 to 2015 and who had a preimplant low frequency pure tone median ≤70 dB HL (n = 63). A retrospective review was completed of the RVEEH database to identify a comparison group who had been implanted with a perimodiolar electrode array, comprising adults implanted between 2004 and 2011 (PM Group) with preimplant hearing equivalent to the TSEA group (n = 70). The TSEA Group were further divided into subgroups in which n = 19 used EAS (TSEA-EAS) and n = 44 who used electric-only hearing (TSEA-Standard). RESULTS: There was no significant difference in median speech perception outcomes between the TSEA and PM Groups (TSEA 61.7%, PM 67.3%, p = 0.954). A significant difference was found between the TSEA-EAS and TSEA-Standard subgroups for median speech perception outcome (TSEA-EAS median 73.5%, TSEA-Standard median 58.3%, p = 0.043). CONCLUSIONS: Significant speech perception benefit following cochlear implantation was achieved with both the perimodiolar and lateral wall electrode arrays and no significant difference was found between outcomes with those array types in this population of adults with functional low frequency hearing pre-implant. Those that received a TSEA, had preserved hearing, and utilised an EAS sound processor performed better than their peers with a TSEA and electric-only hearing.

Clinical outcomes for adult cochlear implant recipients experiencing loss of usable acoustic hearing in the implanted ear.

OBJECTIVES: The first aim of the study was to quantify the change in clinical performance after cochlear implantation for adults who had pre-operative levels of acoustic hearing in each ear of greater than or equal to 46% phoneme score on an open-set monosyllabic word test, and who subsequently experienced loss of useable acoustic hearing in the implanted ear. Pre- and postoperative spatial hearing abilities were assessed, because a clinical consideration for candidates with bilateral acoustic hearing is the potential for post-operative reduction in spatial hearing ability. Second, it was of interest to examine whether preoperative localization ability, as an indicator of access to interaural timing and level cues preoperatively, might be correlated with post-operative change in spatial hearing abilities. DESIGN: Clinical performance measures in the binaural condition were obtained preoperatively and at 12 months postoperatively in 19 postlinguistically hearing-impaired adult subjects. Preoperative localization ability was investigated as a potential correlate with post-operative change in spatial hearing abilities. RESULTS: Significant postoperative group mean improvement in speech perception was observed on measures of open-set monosyllabic word perception in quiet and on an adaptive sentence test presented in coincident 4-talker babble. Observed benefit was greater for a lower presentation level of 55 dB SPL as compared with a conversational speech level of 65 dB SPL. Self-reported ratings of benefit also improved for all questionnaires administered. Objective assessment of localization ability revealed poorer localization postoperatively, although subjective ratings of post-operative change in localization ability in real-world environments were more variable. Postoperative spatial release from masking was not different to that measured preoperatively for the configuration where the side of the head with the hearing aid was advantaged, but improved postoperatively for the configuration that advantaged the implanted side. Preoperative binaural localization ability was not correlated with postoperative spatial hearing abilities. CONCLUSIONS: The findings from this study support cochlear implantation for candidates with pre-operative levels of binaural acoustic hearing within the range examined within the present study. This includes subjects with preoperative open-set monosyllabic word scores ranging from 11 to 62% in the implanted ear, and from 16 to 75% on the contralateral side. Post-operative improvement would be expected for those subjects on a range of clinical measures, even when acoustic hearing was lost in the implanted ear after implantation.

Factors influencing electrical place pitch perception in bimodal listeners.

Factors that might affect perceptual pitch match between acoustic and electric stimulation were examined in 25 bimodal listeners using magnitude estimation. Pre-operative acoustic thresholds in both ears, and duration of severe-profound loss, were first examined as correlates with degree of match between the measured pitch and that predicted by the spiral ganglion frequency-position model. The degree of match was examined with respect to (1) the ratio between the measured and predicted pitch percept on the most apical electrode and (2) the ratio between the slope of the measured and predicted pitch function. Second, effect of listening experience was examined to assess whether adaptation occurred over time to match the frequency assignment to electrodes. Pre-experience pitch estimates on the apical electrode were within the predicted range in only 28% of subjects, and the slope of the electrical pitch function was lower than predicted in all except one subject. Subjects with poorer hearing tended to have a lower pitch and a shallower electrical pitch function than predicted by the model. Pre-operative hearing thresholds in the contralateral ear and hearing loss duration were not correlated with the degree of pitch match, and there was no significant group effect of listening experience.

Outcomes of early- and late-identified children at 3 years of age: findings from a prospective population-based study.

OBJECTIVE: To address the question of whether, on a population level, early detection and amplification improve outcomes of children with hearing impairment. DESIGN: All families of children who were born between 2002 and 2007, and who presented for hearing services below 3 years of age at Australian Hearing pediatric centers in New South Wales, Victoria, and Southern Queensland were invited to participate in a prospective study on outcomes. Children's speech, language, functional, and social outcomes were assessed at 3 years of age, using a battery of age-appropriate tests. Demographic information relating to the child, family, and educational intervention was solicited through the use of custom-designed questionnaires. Audiological data were collected from the national database of Australian Hearing and records held at educational intervention agencies for children. Regression analysis was used to investigate the effects of each of 15 predictor variables, including age of amplification, on outcomes. RESULTS: Four hundred and fifty-one children enrolled in the study, 56% of whom received their first hearing aid fitting before 6 months of age. On the basis of clinical records, 44 children (10%) were diagnosed with auditory neuropathy spectrum disorder. There were 107 children (24%) reported to have additional disabilities. At 3 years of age, 317 children (70%) were hearing aid users and 134 children (30%) used cochlear implants. On the basis of parent reports, about 71% used an aural/oral mode of communication, and about 79% used English as the spoken language at home. Children's performance scores on standardized tests administered at 3 years of age were used in a factor analysis to derive a global development factor score. On average, the global score of hearing-impaired children was more than 1 SD below the mean of normal-hearing children at the same age. Regression analysis revealed that five factors, including female gender, absence of additional disabilities, less severe hearing loss, higher maternal education, and (for children with cochlear implants) earlier age of switch-on were associated with better outcomes at the 5% significance level. Whereas the effect of age of hearing aid fitting on child outcomes was weak, a younger age at cochlear implant switch-on was significantly associated with better outcomes for children with cochlear implants at 3 years of age. CONCLUSIONS: Fifty-six percent of the 451 children were fitted with hearing aids before 6 months of age. At 3 years of age, 134 children used cochlear implants and the remaining children used hearing aids. On average, outcomes were well below population norms. Significant predictors of child outcomes include: presence/absence of additional disabilities, severity of hearing loss, gender, maternal education, together with age of switch-on for children with cochlear implants.

The new Nucleus 5 model cochlear implant: a new surgical technique and early clinical results.

OBJECTIVE: The Nucleus 5 or CI500 series cochlear implants are the new generation of Nucleus(®) cochlear implants. The receiver-stimulator package has a low profile without a pedestal projecting from the medial surface. This study aimed to demonstrate that the new design can facilitate a minimally invasive surgical approach, without the need for tie-down sutures and without a seat drilled for the receiver-stimulator package. METHODS: The surgical technique involved placing the device directly on the surface of the bone in a secure sub-periosteal pocket with a channel drilled for the lead. A well or ramped seat was not drilled and tie-down sutures were not used. Measurements were taken from the transmitting coil to the tragus and the coil to the lobule immediately after implantation, and serially thereafter to document implant position. RESULTS: To date, over 200 implants have been performed with the Nucleus 5 device. In all cases, healing was uneventful without major complications. Of 137 patients with at least 6-week follow-up data, 8% showed a measurement change of greater than 1 cm whereas only 4.4% demonstrated any clinically evident movement. None had any complications relating to migration and none required repositioning of the device. DISCUSSION: The new design can safely be inserted without drilling a well for the receiver-stimulator package. Some early post-operative movement of the package was observed which caused no clinical impact. This modified surgical technique reduces the risk of intracranial complications and reduces operating time.

Initial clinical experience with a totally implantable cochlear implant research device.

OBJECTIVE: To evaluate the effectiveness and issues associated with a research totally implantable cochlear implant (TIKI). STUDY DESIGN: Limited patient trial. SETTING: Tertiary referral center. PATIENTS: Three adult human subjects with severe-to-profound sensorineural hearing loss. INTERVENTIONS: Subjects were implanted with a research TIKI developed by Cochlear Limited and the Co-operative Research Centre for Cochlear Implant and Hearing Aid Innovation. The TIKI has a lithium ion rechargeable battery, a package-mounted internal microphone, and sound-processing electronics that enable the use of "invisible hearing" without the use of an external device. The TIKI also functions with an external ESPrit 3G sound processor as a conventional cochlear implant. The standard surgical technique was modified to accommodate the larger device package. Postoperatively, subjects used TIKI in both invisible hearing and the conventional ESPrit 3G modes. MAIN OUTCOME MEASURES: Device use was recorded in both invisible hearing and ESPrit 3G listening modes. Performance of the internal battery and microphone was assessed over time. Psychophysical MAP data were collected, and speech perception was measured at 1, 3, 6, and 12 months postoperatively in both listening modes. RESULTS: There were no surgical or postoperative complications. All subjects use both invisible hearing and conventional ESPrit 3G modes. Speech perception outcomes for all patients showed improvement from preoperative scores. As a consequence of the reduced sensitivity of the implanted microphone, speech perception results using the invisible hearing mode were significantly lower than the ESPrit 3G mode. Subjects reported some body noise interference that limited use of the invisible hearing mode; however, all continue to use the invisible hearing mode on a limited daily basis. The rechargeable battery functioned well, with a cycle time indicating the low-power implant design is effective and will deliver long battery life. CONCLUSION: This study demonstrates that the challenges in developing a safe and effective TIKI can be overcome. Three subjects implanted with the research TIKI all reported benefit from routine use. For each subject, hearing outcomes using invisible hearing mode were not as good as when using the external ESPrit 3G sound processor in the conventional mode.

Psychophysical measures in patients fitted with Contour and straight Nucleus electrode arrays.

The objective of this study was to compare the psychophysical performance of patients using the Nucleus Contour electrode array with that of patients using the straight banded-electrode array. In particular, we wished to consider how psychophysical parameters would differ for an electrode array positioned closer to the modiolus, and how this might influence both patient benefits and the design of speech processing strategies. Nine subjects participated in the study: four used the Nucleus straight array and five used the Nucleus Contour electrode array. Radiographic analyses found that the Contour array lay closer to the modiolus, was more deeply inserted and spanned a larger fractional length of the basilar membrane than the straight banded-electrode array. The results were analysed in terms of array type and of the position of the individual electrode band, both distance from the modiolus and longitudinal placement. Mean threshold was lower for the Contour array but maximum comfortable level was similar. Whereas threshold varied significantly with distance of electrode band from the modiolus, maximum comfortable level did not. Pitch varied fairly regularly with longitudinal position of the stimulated electrode, with the exception of one Contour subject. The forward masking profiles, using moderately loud maskers, were narrower for the Contour array, indicative of more localized neural excitation.

A psychophysical forward masking comparison of longitudinal spread of neural excitation in the Contour and straight Nucleus electrode arrays.

The objective of the study was to compare the widths of forward masking profiles in subjects implanted with the Nucleus 24 Contour or straight electrode array. The Contour array is typically positioned closer to the modiolus than the straight array. Subjects were fourteen postlingually hearing-impaired adults with severe-profound hearing loss, seven used the Contour array and seven used the straight array. Forward masking profiles were measured at three positions along the array (apical, mid, and basal) using maskers at the 15% loudness level. It was hypothesized that masking profile widths would be more sensitive to differences in distance from the neural structures using low-level maskers. Masking width was calculated at the 50% point of the masking peak amplitude. There were no significant differences in masking widths between Contour and straight array subject groups. Current levels for hearing thresholds and maximum comfortable listening levels were significantly lower for the Contour array subjects.

Measurement and analysis of access resistance and polarization impedance in cochlear implant recipients.

BACKGROUND: Impedance measurements are commonly performed at the end of cochlear implant surgery, not only to confirm that all electrodes are working but also to monitor the impedances of the newly implanted electrodes. The current method of testing allows the determination of only the overall electrode impedance but not its components, access resistance and polarization impedance. To determine whether any longitudinal change in the electrode impedance is caused by a change in the endocochlear environment or rather caused by a change in the surface quality of the electrode, it is necessary to extract access resistance and polarization impedance. METHODS: We applied an impedance model that enabled us to calculate access resistance and polarization impedance after measurement of electrode impedance at three points along the voltage waveform. RESULTS: The results show that the value of the components of electrode impedance varied with time after surgery: access resistance increased slowly over time, whereas polarization impedance increased up to Week 2 but decreased after commencement of electrical stimulation at that stage. These results are consistent with the hypothesis that a layer of fibrous tissue forms around the electrode within the cochlear canal, resulting in a slow increase of access resistance, whereas a layer of proteins forms on the surface of the electrode in the early phase after implantation. Electrical stimulation appears to disperse this surface layer, thereby reducing both the polarization impedance and electrode impedance. CONCLUSION: The method presented enables the extraction of more detailed information about the longitudinal changes in the intracochlear environment after cochlear implantation.

Poly-vinyl-alcohol (PVA) coating of cochlear implant electrode arrays: an in-vivo biosafety study.

OBJECTIVE: The tissue response and biosafety of poly-vinyl-alcohol (PVA) has been investigated to explore its potential use as an agent to straighten pre-curved cochlear implant electrode arrays for surgical insertion. METHODS: Test arrays were implanted either subcutaneously or into the cochlea of guinea pigs for 3 months. The arrays were uncoated (Treatment 1) or coated with low molecular weight (MW) PVA (Treatment 2), high MW PVA (Treatment 3) or a 50:50 mixture of low and high MW PVA (Treatment 4). After explantation the tissues were examined histologically. RESULTS: In both study groups, Treatment 2 dissolved completely and induced the least tissue reaction, while Treatments 3 and 4 not only dissolved incompletely, but also induced more fibrous tissue growth. Treatment 4 coated arrays induced severe insertion trauma in all the cochleas, most likely due to the thickness of the coat and the resulting rigidity of the array. Spiral ganglion cell density (SGCD) in the basal turn of the scala tympani was reduced for both Treatments 2 and 4. While the reduction in SGCD in the Treatment 4 group is likely to be a result of the insertion trauma caused and the subsequent loss of peripheral dendrites, it is unknown what caused the reduction of SGCD in the Treatment 2 group. CONCLUSION: Prior to the specific use of PVA as electrode array coating material, the ideal composition and its biosafety needs to be reassessed.

Spatial spread of neural excitation in cochlear implant recipients: comparison of improved ECAP method and psychophysical forward masking.

This study introduces and evaluates a method for measurement of the longitudinal spread of electrically evoked neural excitation in the cochlea, using the Neural Response Telemetry system (NRT) available with the Nucleus((R)) 24 cochlear implant system. The recently released version of the NRT software (version 3.0) enables presentation of the 'masker' and 'probe' on different electrodes. In the present method the probe position was fixed, while the masker position was varied across the electrode array. The amplitude of the response to the partially masked probe provides a measure of the amount of masking, which is dependent on the extent of overlap of the excitation regions of the masker and probe. These measurements were performed in seven subjects implanted with the Nucleus 24 cochlear implant system (four with straight and three with Contour electrode arrays), for basal, middle and apical probe electrodes. Similar excitation profiles were obtained using either the standard NRT subtraction paradigm or an alternative 'Miller' method. The excitation profiles were compared with those obtained from psychophysical forward masking and good agreement was found. The widths of electrically evoked compound action potential (ECAP) and forward masking profiles did not differ significantly. Whereas the width of the ECAP measure was significantly correlated with both the maximum comfortable level and the distance of the electrode band from the modiolus, the width of the forward masking profile was not.

Assessing children with profound hearing loss and severe language delay: getting a broader picture.

Six children with profound hearing loss and severe language delay participated in this pilot study. Four of the children used a Nucleus multi-channel cochlear implant only, while two wore binaural hearing aids. All the children had been diagnosed at an early age, fitted with a sensory device soon after, had considerable device experience and had attended an auditory oral early intervention setting. All the children were identified as having slower-than-expected development of spoken language. The study identified a number of potentially contributory factors including: inconsistency of device use and low levels of functioning on conversational attentiveness, speech perception, speech intelligibility, pragmatics, social competence, behaviour and temperament.