The effects of hearing loss on the contribution of high- and low-frequency speech information to speech understanding. II. Sloping hearing loss

High-Frequency Gain and Maximum Output Effects on Speech Recognition in Bone-Conduction Hearing Devices: Blinded Study

INTRODUCTION

Bone-conduction hearing device (BCHD) uses natural sound transmission through bone and soft tissue, directly to the cochlea, via an external processor that captures and processes sound, which is converted into mechanical vibrations. Key parameters, as maximum power output (MPO) and broader frequency range (FR), must be considered when indicating a BCHD because they can be decisive for speech recognition, especially under listening challenge conditions.

OBJECTIVES

Compare hearing performance and speech recognition in noise of two sound processors (SPs), with different features of MPO and FR, among BCHD users.

MATERIALS AND METHODS

This single-blinded, comparative, observational study evaluated 21 individuals Baha 4 system users with conductive or mixed hearing impairment. The free-field audiometry and speech recognition results were blindly collected under the following conditions: unaided, with Baha 5, and with Baha 6 Max SP.

RESULTS

In free-field audiometry, significant differences were observed between the SP at 0.25, 3, 4, 6, and 8 kHz, with Baha 6 Max outperforming Baha 5. The Baha 6 Max provided significantly better speech recognition than Baha 5 under all the speech in noise conditions evaluated. Separating the transcutaneous from the percutaneous users, Baha 6 Max Attract SP provided the best results and significantly lowered the free-field thresholds than Baha 5 Attract. The Baha 6 Max also significantly improved speech recognition in noise, among both Attract and Connect users.

CONCLUSION

The present study revealed that the greater MPO and broader FR of the Baha 6 Max device helped increase high-frequency gain and improved speech recognition in BCHD-experimented users.

Exploring level- and spectrum-based music mixing transforms for hearing-impaired listeners

Multitrack mixing is an essential practice in modern music production. Research on automatic-mixing paradigms, however, has mostly tested samples of trained, normal hearing (NH) participants. The goal of the present study was to explore mixing paradigms for hearing-impaired (HI) listeners. In two experiments, the mixing preferences of NH and HI listeners with respect to the parameters of lead-to-accompaniment level ratio (LAR) and the low to high frequency spectral energy balance were investigated. Furthermore, preferences of transformed equalization (EQ-transform) were assessed, achieved by linearly extrapolating between the power spectrum of individual tracks and a reference spectrum. Multitrack excerpts of popular music were used as stimuli. Results from experiment 1 indicate that HI participants preferred an elevated LAR compared to NH participants but did not suggest distinct preferences regarding spectral balancing or EQ-transform. Results from experiment 2 showed that bilateral hearing aid (HA) disuse among the HI participants yielded higher LAR values, stronger weighting of higher frequencies, as well as sparser EQ-transform settings compared to a condition with HA use. Overall, these results suggest that adjusting multitrack mixes may be a valuable way for making music more accessible for HI listeners.

Association of Clinical Aspects and Genetic Variants with the Severity of Cisplatin-Induced Ototoxicity in Head and Neck Squamous Cell Carcinoma: A Prospective Cohort Study

Background: Cisplatin (CDDP) is a major ototoxic chemotherapy agent for head and neck squamous cell carcinoma (HNSCC) treatment. Clinicopathological features and genotypes encode different stages of CDDP metabolism, as their coexistence may influence the prevalence and severity of hearing loss. Methods: HNSCC patients under CDDP chemoradiation were prospectively provided with baseline and post-treatment audiometry. Clinicopathological features and genetic variants encoding glutathione S-transferases (GSTT1, GSTM1, GSTP1), nucleotide excision repair (XPC, XPD, XPF, ERCC1), mismatch repair (MLH1, MSH2, MSH3, EXO1), and apoptosis (P53, CASP8, CASP9, CASP3, FAS, FASL)-related proteins were analyzed regarding ototoxicity. Results: Eighty-nine patients were included, with a cumulative CDDP dose of 260 mg/m2. Moderate/severe ototoxicity occurred in 26 (29%) patients, particularly related to hearing loss at frequencies over 3000 Hertz. Race, body-mass index, and cumulative CDDP were independent risk factors. Patients with specific isolated and combined genotypes of GSTM1, GSTP1 c.313A>G, XPC c.2815A>C, XPD c.934G>A, EXO1 c.1762G>A, MSH3 c.3133A>G, FASL c.-844A>T, and P53 c.215G>C SNVs had up to 32.22 higher odds of presenting moderate/severe ototoxicity. Conclusions: Our data present, for the first time, the association of combined inherited nucleotide variants involved in CDDP efflux, DNA repair, and apoptosis with ototoxicity, which could be potential predictors in future clinical and genomic models.

Ontogeny of cellular organization and LGR5 expression in porcine cochlea revealed using tissue clearing and 3D imaging

Over 11% of the world's population experience hearing loss. Although there are promising studies to restore hearing in rodent models, the size, ontogeny, genetics, and frequency range of hearing of most rodents' cochlea do not match that of humans. The porcine cochlea can bridge this gap as it shares many anatomical, physiological, and genetic similarities with its human counterpart. Here, we provide a detailed methodology to process and image the porcine cochlea in 3D using tissue clearing and light-sheet microscopy. The resulting 3D images can be employed to compare cochleae across different ages and conditions, investigate the ontogeny of cochlear cytoarchitecture, and produce quantitative expression maps of LGR5, a marker of cochlear progenitors in mice. These data reveal that hair cell organization, inner ear morphology, cellular cartography in the organ of Corti, and spatiotemporal expression of LGR5 are dynamic over developmental stages in a pattern not previously documented.

Obstructive sleep apnea risk and hearing impairment among occupational noise-exposed male workers

This study aimed to investigate the association between obstructive sleep apnea (OSA) risk and hearing impairment among workers exposed to occupational noise. A cross-sectional study was conducted among 607 healthy male workers at a tire-manufacturing factory. The subjects underwent audiometric testing, and their OSA risk was examined based on the STOP-Bang questionnaire. Hearing impairment was defined as a hearing threshold >25 dB hearing level (HL) in any frequency of 1, 2, 3 and 4 kHz in either ear. High OSA risk was defined as a STOP-bang score of ≥3. Hearing thresholds at 1, 2, 3 and 4 kHz in both ears were significantly higher among workers with high OSA risk than among those with low OSA risk after adjusting for confounders. Multiple logistic regression analysis examining the association of OSA risk and STOP-Bang score with hearing impairment revealed an odds ratio of 1.738 (95% confidence interval [CI] 1.113-2.713, p = 0.015) and 1.256 (95% CI 1.031-1.529, p = 0.023), respectively, after adjusting for confounders. In addition, when the hearing impairment was reclassified into high- and low-frequency hearing impairment, a statistically significant OR was seen for high-frequency hearing impairment. In conclusion, high OSA risk was associated with hearing impairment in occupational noise-exposed workers, especially in the high-frequency range of 3 and 4 kHz. More efforts are required to improve the management of OSA and its risk factors to preserve hearing in occupational noise-exposed workers.

Predicting neural deficits in sensorineural hearing loss from word recognition scores

The current gold standard of clinical hearing assessment includes a pure-tone audiogram combined with a word recognition task. This retrospective study tests the hypothesis that deficits in word recognition that cannot be explained by loss in audibility or cognition may reflect underlying cochlear nerve degeneration (CND). We collected the audiological data of nearly 96,000 ears from patients with normal hearing, conductive hearing loss (CHL) and a variety of sensorineural etiologies including (1) age-related hearing loss (ARHL); (2) neuropathy related to vestibular schwannoma or neurofibromatosis of type 2; (3) Ménière’s disease; (4) sudden sensorineural hearing loss (SSNHL), (5) exposure to ototoxic drugs (carboplatin and/or cisplatin, vancomycin or gentamicin) or (6) noise damage including those with a 4-kHz “noise notch” or reporting occupational or recreational noise exposure. Word recognition was scored using CID W-22 monosyllabic word lists. The Articulation Index was used to predict the speech intelligibility curve using a transfer function for CID W-22. The level at which maximal intelligibility was predicted was used as presentation level (70 dB HL minimum). Word scores decreased dramatically with age and thresholds in all groups with SNHL etiologies, but relatively little in the conductive hearing loss group. Discrepancies between measured and predicted word scores were largest in patients with neuropathy, Ménière’s disease and SSNHL, intermediate in the noise-damage and ototoxic drug groups, and smallest in the ARHL group. In the CHL group, the measured and predicted word scores were very similar. Since word-score predictions assume that audiometric losses can be compensated by increasing stimulus level, their accuracy in predicting word score for CHL patients is unsurprising. The lack of a strong age effect on word scores in CHL shows that cognitive decline is not a major factor in this test. Amongst the possible contributions to word score discrepancies, CND is a prime candidate: it should worsen intelligibility without affecting thresholds and has been documented in human temporal bones with SNHL. Comparing the audiological trends observed here with the existing histopathological literature supports the notion that word score discrepancies may be a useful CND metric.

Effects of extended high frequency bandwidth in osseointegrated bone conduction device users

High-frequency hearing above 5000 Hz improves the detection and discrimination of high frequency phonemes. Improved access to high-frequency hearing may be particularly advantageous in unilaterally deafened listeners who experience reduced access to high frequency speech cues on their impaired side and decreased speech perception abilities in competing noise. This study aimed to investigate the effects of extended high-frequency bandwidth on speech perception in unilaterally deafened osseointegrated bone conduction hearing device recipients. To study the effect of extended high-frequency bandwidth, participants underwent aided testing in narrow bandwidth and extended high-frquency bandwidth BCD listening conditions. Aided word and phoneme recognition in quiet was assessed at soft and conversational speech levels with the better ear plugged. Aided thresholds and Ling 6 phoneme sounds were also assessed in quiet with the better ear plugged. Speech perception in noise was assessed at ± 90° and co-located at 0° using the adaptive Hearing in Noise Test. Findings demonstrate a significant improvement in speech perception outcomes when listening with extended high-frequency bandwidth. Extended high-frequency bandwidth significantly improved word and phoneme recognition for soft and average conversational speech. The largest effects were observed for voiceless phonemes. Results suggest use of bone conduction devices with extended high-frequency bandwidth result in improved hearing outcomes when compared with narrow bandwidth bone conduction devices.

Audiology Practices in the Preoperative Evaluation and Management of Adult Cochlear Implant Candidates

Importance

Currently, no clear guidelines exist regarding clinical testing methods for identifying adult cochlear implant (CI) candidates. Indications provided by the US Food and Drug Administration, Medicare, and private insurers are ambiguous concerning test materials and the level and mode of test presentation. This could lead to wide variability in clinical assessment and, potentially, unequal access to CIs for individuals with clinically significant hearing loss.

Objective

To examine the preoperative testing methods used by audiologists in evaluating adult CI candidates across the United States.

Design, Setting, and Participants

A survey assessing audiology practice patterns was created using a Research Electronic Data Capture system hosted at the University of Miami. A link to a survey (65 questions in multiple-choice or rank-order format was distributed electronically along with a request for completion to members of the American Cochlear Implant Alliance and to the Institute for Cochlear Implant Training forum. Responses were collected from January 17 to June 4, 2018. Participation was limited to audiologists who evaluate adult CI candidates, and respondents who do not provide adult CI care were excluded. Collected demographic information included work setting, years of experience, and highest level of education attained.

Main Outcomes and Measures

Percentages, medians, and interquartile ranges were from aggregated responses concerning hearing aid verification methods; testing methods, materials, and practices; nonauditory factors that might affect CI candidacy; audiology practice patterns; and expanded indications for CIs.

Results

Anonymized surveys were returned by 99 respondents; because surveys were available electronically, the number of audiologists who viewed the survey but did not respond was not available. Seven respondents identified themselves as pediatric specialists and were excluded, resulting in a total of 92 surveys available for analysis (denominators vary because respondents could complete the survey without answering all questions). Seventy percent of respondents (51 of 72) were doctors of audiology, and nearly 50% (33 of 74) were employed at universities and academic centers performing more than 50 CIs per year. When assessing adult candidacy for implant, most respondents reported using test materials from the Minimum Speech Test Battery: 96% (51 of 53), using AzBio sentences in quiet; 89% (47 of 53), AzBio sentences in noise; and 100% (53 of 53), the consonant-vowel nucleus-consonant, monosyllabic words test. However, these tests were applied inconsistently, with 39 of 53 respondents (74%) reporting use of a sound pressure level scale and the other 14 (26%) a hearing level scale at various decibel levels, and with some using a single signal-to-noise ratio and others using multiple ratios for sound-in-noise tests. Respondents' definitions of the best aided listening condition for assessing implant candidates also varied widely. Among the nonauditory factors ranked most important for assessing CI candidacy were patient's level of cognition and expectations of CI; yet, few respondents reported including cognitive or psychological tests in the assessment protocol.

Conclusions and Relevance

Findings of this study reveal considerable variability in preoperative testing methods and practices across health care professionals assessing adult candidates for CI. This lack of standardization in the delivery of care may increase the risk for health care inequities, specifically in access to care for adults with clinically significant hearing loss.

Flexible Piezoelectric Acoustic Sensors and Machine Learning for Speech Processing

Flexible piezoelectric acoustic sensors have been developed to generate multiple sound signals with high sensitivity, shifting the paradigm of future voice technologies. Speech recognition based on advanced acoustic sensors and optimized machine learning software will play an innovative interface for artificial intelligence (AI) services. Collaboration and novel approaches between both smart sensors and speech algorithms should be attempted to realize a hyperconnected society, which can offer personalized services such as biometric authentication, AI secretaries, and home appliances. Here, representative developments in speech recognition are reviewed in terms of flexible piezoelectric materials, self-powered sensors, machine learning algorithms, and speaker recognition.

Individualized estimation of the Speech Intelligibility Index for short sentences: Test-retest reliability

The speech intelligibility index (SII) model was modified to allow individualized parameters. These parameters included the relative weights of speech cues in five octave-frequency bands ranging from 0.25 to 4 kHz, i.e., the band importance function, and the transfer function that allows the SII to generate predictions on speech-recognition scores. A Bayesian adaptive procedure, the quick-band-importance-function (qBIF) procedure, was utilized to enable efficient estimation of the SII parameters from individual listeners. In two experiments, the SII parameters were estimated for 30 normal-hearing adults using Institute of Electrical and Electronics Engineers (IEEE) sentences at speech levels of 55, 65, and 75 dB sound pressure level (in Experiment I) and for 15 hearing-impaired (HI) adult listeners using amplified IEEE or AzBio sentences (in Experiment II). In both experiments, even without prior training, the estimated model parameters showed satisfactory reliability between two runs of the qBIF procedure at least one week apart. For the HI listeners, inter-listener variability in most estimated SII parameters was larger than intra-listener variability of the qBIF procedure.

Sound-Absorption Coefficient of Bark-Based Insulation Panels

The objective of this study was to investigate the sound absorption coefficient of bark-based insulation panels made of softwood barks Spruce (Picea abies (L.) H. Karst.) and Larch (Larix decidua Mill.) by means of impedance tube, with a frequency range between 125 and 4000 Hz. The highest efficiency of sound absorption was recorded for spruce bark-based insulation boards bonded with urea-formaldehyde resin, at a level of 1000 and 2000 Hz. The potential of noise reduction of larch bark-based panels glued with tannin-based adhesive covers the same frequency interval. The experimental results show that softwood bark, an underrated material, can substitute expensive materials that involve more grey energy in sound insulation applications. Compared with wood-based composites, the engineered spruce bark (with coarse-grained and fine-grained particles) can absorb the sound even better than MDF, particleboard or OSB. Therefore, the sound absorption coefficient values strengthen the application of insulation panels based on tree bark as structural elements for the noise reduction in residential buildings, and concurrently they open the new ways for a deeper research in this field.

Speech recognition, loudness, and preference with extended bandwidth hearing aids for adult hearing aid users

Objective: In contrast to the past, some current hearing aids can provide gain for frequencies above 4-5 kHz. This study assessed the effect of wider bandwidth on outcome measures using hearing aids fitted with the DSL v5.0 prescription.Design: There were two conditions: an extended bandwidth condition, for which the maximum available bandwidth was provided, and a restricted bandwidth condition, in which gain was reduced for frequencies above 4.5 kHz. Outcome measures were assessed in both conditions.Study sample: Twenty-four participants with mild-to-moderately-severe sensorineural high-frequency sloping hearing loss.Results: Providing extended bandwidth resulted in maximum audible output frequency values of 7.5 kHz on average for an input level of 65 dB SPL. An improvement in consonant discrimination scores (4.1%), attributable to better perception of /s/, /z/, and /t/ phonemes, was found in the extended bandwidth condition, but no significant change in loudness perception or preferred listening levels was found. Most listeners (79%) had either no preference (33%) or some preference for the extended bandwidth condition (46%).Conclusions: The results suggest that providing the maximum bandwidth available with modern hearing aids fitted with DSL v5.0, using targets from 0.25 to 8 kHz, can be beneficial for the tested population.

Nucleus Hybrid S12: Multicenter Clinical Trial Results

OBJECTIVES/HYPOTHESIS

The use of a short 10-mm/10-electrode cochlear implant to preserve low-frequency residual hearing was investigated. This report describes the 12-month outcomes of this multicenter clinical trial.

STUDY DESIGN

Single-subject design.

METHODS

Twenty-eight subjects with low-frequency hearing at or better than 60 dB HL at 500 Hz and severe high-frequency hearing loss were implanted with a Nucleus Hybrid S12 implant in their poorer ear. Speech perception in quiet using Consonant-Nucleus-Consonant (CNC) words and sentences in noise using AzBio sentences was collected pre- and postoperatively at 3, 6, and 12 months. Subjective reporting using the Speech, Spatial, and Qualities of Hearing Scale (SSQ) questionnaire was also collected pre- and postoperatively.

RESULTS

Functional hearing preservation was accomplished in 96% of subjects. At 3 and 6 months, 86% of the 28 subjects had maintained functional hearing. By 12 months, 23 out of 27 subjects (85%) had maintained functional hearing (one subject with functional hearing at 6 months withdrew from the study prior to the 12-month visit). Speech perception results demonstrated that 81% of the participants on CNC words and 77% with AzBio sentences in noise had significant improvements using their everyday listening condition at 12 months compared to preoperative performance with bilateral hearing aids. Furthermore, preoperative to 12 months postoperative subjective ratings showed significant improvements for the SSQ.

CONCLUSIONS

This study demonstrates that a high degree of hearing preservation enabling acoustic-electric hearing and improvement in speech understanding in quiet and in noise can be accomplished using a short-electrode 10-mm cochlear implant.

LEVEL OF EVIDENCE

2c Laryngoscope, 130:E548-E558, 2020.

Prospective Study of Dietary Patterns and Hearing Threshold Elevation

We conducted a prospective study of dietary patterns and longitudinal change in audiometric hearing thresholds among 3,135 women (mean age = 59 years) in the Nurses' Health Study II (2012-2018). Diet adherence scores for the Dietary Approaches to Stop Hypertension (DASH) and Alternate Mediterranean (AMED) diets and the Alternate Healthy Eating Index 2010 (AHEI-2010) were calculated using validated food-frequency questionnaires. Baseline and 3-year follow-up hearing sensitivities were assessed by pure-tone audiometry at 19 US sites. We used multivariable-adjusted logistic regression models to examine independent associations between diet adherence scores and risk of ≥5 dB elevation in the pure-tone average (PTA) of low-frequency (LPTA0.5,1,2 kHz), mid-frequency (MPTA3,4 kHz), and high-frequency (HPTA6,8 kHz) hearing thresholds. Higher adherence scores were associated with lower risk of hearing loss. Compared with the lowest quintile of DASH score, the multivariable-adjusted odds ratios for mid-frequency and high-frequency threshold elevation in the highest quintile were 0.71 (95% confidence interval (CI): 0.55, 0.92; P for trend = 0.003) and 0.75 (95% CI: 0.59, 0.96; P for trend = 0.02); for AMED and AHEI scores, for mid-frequency threshold elevation, they were 0.77 (95% CI: 0.60, 0.99; P for trend = 0.02) and 0.72 (95% CI: 0.57, 0.92; P for trend = 0.002). Nonsignificant inverse associations were observed for high-frequency threshold elevation. There were no significant associations between adherence scores and low-frequency threshold elevation. Our findings indicate that eating a healthy diet might reduce the risk of acquired hearing loss.

The Effect of Hearing Aid Bandwidth and Configuration of Hearing Loss on Bimodal Speech Recognition in Cochlear Implant Users

OBJECTIVES

(1) To determine the effect of hearing aid (HA) bandwidth on bimodal speech perception in a group of unilateral cochlear implant (CI) patients with diverse degrees and configurations of hearing loss in the nonimplanted ear, (2) to determine whether there are demographic and audiometric characteristics that would help to determine the appropriate HA bandwidth for a bimodal patient.

DESIGN

Participants were 33 experienced bimodal device users with postlingual hearing loss. Twenty three of them had better speech perception with the CI than the HA (CI>HA group) and 10 had better speech perception with the HA than the CI (HA>CI group). Word recognition in sentences (AzBio sentences at +10 dB signal to noise ratio presented at 0° azimuth) and in isolation [CNC (consonant-nucleus-consonant) words] was measured in unimodal conditions [CI alone or HAWB, which indicates HA alone in the wideband (WB) condition] and in bimodal conditions (BMWB, BM2k, BM1k, and BM500) as the bandwidth of an actual HA was reduced from WB to 2 kHz, 1 kHz, and 500 Hz. Linear mixed-effect modeling was used to quantify the relationship between speech recognition and listening condition and to assess how audiometric or demographic covariates might influence this relationship in each group.

RESULTS

For the CI>HA group, AzBio scores were significantly higher (on average) in all bimodal conditions than in the best unimodal condition (CI alone) and were highest at the BMWB condition. For CNC scores, on the other hand, there was no significant improvement over the CI-alone condition in any of the bimodal conditions. The opposite pattern was observed in the HA>CI group. CNC word scores were significantly higher in the BM2k and BMWB conditions than in the best unimodal condition (HAWB), but none of the bimodal conditions were significantly better than the best unimodal condition for AzBio sentences (and some of the restricted bandwidth conditions were actually worse). Demographic covariates did not interact significantly with bimodal outcomes, but some of the audiometric variables did. For CI>HA participants with a flatter audiometric configuration and better mid-frequency hearing, bimodal AzBio scores were significantly higher than the CI-alone score with the WB setting (BMWB) but not with other bandwidths. In contrast, CI>HA participants with more steeply sloping hearing loss and poorer mid-frequency thresholds (≥82.5 dB) had significantly higher bimodal AzBio scores in all bimodal conditions, and the BMWB did not differ significantly from the restricted bandwidth conditions. HA>CI participants with mild low-frequency hearing loss showed the highest levels of bimodal improvement over the best unimodal condition on CNC words. They were also less affected by HA bandwidth reduction compared with HA>CI participants with poorer low-frequency thresholds.

CONCLUSIONS

The pattern of bimodal performance as a function of the HA bandwidth was found to be consistent with the degree and configuration of hearing loss for both patients with CI>HA performance and for those with HA>CI performance. Our results support fitting the HA for all bimodal patients with the widest bandwidth consistent with effective audibility.

Current Profile of Adults Presenting for Preoperative Cochlear Implant Evaluation

Considerable advancements in cochlear implant technology (e.g., electric acoustic stimulation) and assessment materials have yielded expanded criteria. Despite this, it is unclear whether individuals with better audiometric thresholds and speech understanding are being referred for cochlear implant workup and pursuing cochlear implantation. The purpose of this study was to characterize the mean auditory and demographic profile of adults presenting for preoperative cochlear implant workup. Data were collected prospectively for all adult preoperative workups at Vanderbilt from 2013 to 2015. Subjects included 287 adults (253 postlingually deafened) with a mean age of 62.3 years. Each individual was assessed using the minimum speech test battery, spectral modulation detection, subjective questionnaires, and cognitive screening. Mean consonant-nucleus-consonant word scores, AzBio sentence scores, and pure-tone averages for postlingually deafened adults were 10%, 13%, and 89 dB HL, respectively, for the ear to be implanted. Seventy-three individuals (25.4%) met labeled indications for Hybrid-L and 207 individuals (72.1%) had aidable hearing in the better hearing ear to be used in a bimodal hearing configuration. These results suggest that mean speech understanding evaluated at cochlear implant workup remains very low despite recent advancements. Greater awareness and insurance accessibility may be needed to make cochlear implant technology available to those who qualify for electric acoustic stimulation devices as well as individuals meeting conventional cochlear implant criteria.

Combined Electric and Acoustic Stimulation With Hearing Preservation: Effect of Cochlear Implant Low-Frequency Cutoff on Speech Understanding and Perceived Listening Difficulty

OBJECTIVE

The primary objective of this study was to assess the effect of electric and acoustic overlap for speech understanding in typical listening conditions using semidiffuse noise.

DESIGN

This study used a within-subjects, repeated measures design including 11 experienced adult implant recipients (13 ears) with functional residual hearing in the implanted and nonimplanted ear. The aided acoustic bandwidth was fixed and the low-frequency cutoff for the cochlear implant (CI) was varied systematically. Assessments were completed in the R-SPACE sound-simulation system which includes a semidiffuse restaurant noise originating from eight loudspeakers placed circumferentially about the subject's head. AzBio sentences were presented at 67 dBA with signal to noise ratio varying between +10 and 0 dB determined individually to yield approximately 50 to 60% correct for the CI-alone condition with full CI bandwidth. Listening conditions for all subjects included CI alone, bimodal (CI + contralateral hearing aid), and bilateral-aided electric and acoustic stimulation (EAS; CI + bilateral hearing aid). Low-frequency cutoffs both below and above the original "clinical software recommendation" frequency were tested for all patients, in all conditions. Subjects estimated listening difficulty for all conditions using listener ratings based on a visual analog scale.

RESULTS

Three primary findings were that (1) there was statistically significant benefit of preserved acoustic hearing in the implanted ear for most overlap conditions, (2) the default clinical software recommendation rarely yielded the highest level of speech recognition (1 of 13 ears), and (3) greater EAS overlap than that provided by the clinical recommendation yielded significant improvements in speech understanding.

CONCLUSIONS

For standard-electrode CI recipients with preserved hearing, spectral overlap of acoustic and electric stimuli yielded significantly better speech understanding and less listening effort in a laboratory-based, restaurant-noise simulation. In conclusion, EAS patients may derive more benefit from greater acoustic and electric overlap than given in current software fitting recommendations, which are based solely on audiometric threshold. These data have larger scientific implications, as previous studies may not have assessed outcomes with optimized EAS parameters, thereby underestimating the benefit afforded by hearing preservation.

Patient-Reported Outcomes From the United States Clinical Trial for a Hybrid Cochlear Implant

OBJECTIVE

To assess patient-reported outcomes (PROs) in individuals with significant residual low-frequency hearing and severe-to-profound high-frequency sensorineural hearing loss (SNHL) who received the hybrid cochlear implant (CI).

STUDY DESIGN

Prospective, multicenter, nonrandomized, single-arm repeated measures, single-subject design.

SETTING

Tertiary centers, ambulatory care.

PATIENTS

Fifty adults with severe-to-profound high-frequency SNHL and residual low-frequency hearing with aided word recognition scores between 10 and 60% in the ear to be implanted, and in the contralateral ear greater than or equal to implant ear less than or equal to 80%.

INTERVENTION

Therapeutic; hybrid CI.

MAIN OUTCOME MEASURES

Speech, spatial and qualities of hearing scale (SSQ), device use questionnaire (DUQ), University of Washington Clinical Assessment of Music Perception (UW-CAMP) assessed preoperatively and after 6 and 12 (SSQ and DUQ only) months of hybrid CI use.

RESULTS

Significant improvements in mean SSQ ratings were demonstrated at 6 and 12 months postactivation overall and for domains related to speech hearing, spatial hearing, and sound quality. Significant improvement was also found for overall satisfaction on the DUQ and across a number of specific listening situations in addition to aspects related to social engagement. UW-CAMP pitch discrimination and melody and timbre recognition abilities were not compromised postoperatively, allowing hybrid subjects to maintain superior music perception abilities than typically observed with standard CIs.

CONCLUSIONS

Patients who received the hybrid CI demonstrated significant PRO benefits on the SSQ and the DUQ after 6 and 12 months of CI use. In addition, given the opportunity to maintain useful low-frequency acoustic hearing, patients retained music listening abilities, as assessed by the UW-CAMP.

Minimum Reporting Standards for Adult Cochlear Implantation

This article outlines new minimum standards for reporting adult cochlear implant outcomes. These standards have been endorsed by the Implantable Hearing Devices Committee and the Hearing Committee of the American Academy of Otolaryngology-Head and Neck Surgery. The lack of a standardized method for reporting outcomes following cochlear implantation in clinical trials has hampered the ability of investigators to draw comparisons across studies. Variability in data reported in articles and presentation formats inhibits meta-analyses, making it impossible to accumulate the large patient cohorts needed for statistically significant inference. While investigators remain unrestricted in publishing their adult cochlear implant outcome data in additional formats that they believe to be valuable, they should include the presently proposed minimal data set to facilitate interstudy comparability and consistency of reporting.

Preliminary evaluation of a novel non-linear frequency compression scheme for use in children

OBJECTIVE

The primary goal of this study was to evaluate a new form of non-linear frequency compression (NLFC) in children. The new NLFC processing scheme is adaptive and potentially allows for a better preservation of the spectral characteristics of the input sounds when compared to conventional NLFC processing.

DESIGN

A repeated-measures design was utilised to compare the speech perception of the participants with two configurations of the new adaptive NLFC processing to their performance with the existing NLFC. The outcome measures included the University of Western Ontario Plurals test, the Consonant-Nucleus-Consonant word recognition test, and the Phonak Phoneme Perception test.

STUDY SAMPLE

Study participants included 14 children, aged 6-17 years, with mild-to-severe low-frequency hearing loss and severe-to-profound high-frequency hearing loss.

RESULTS

The results indicated that the use of the new adaptive NLFC processing resulted in significantly better average word recognition and plural detection relative to the conventional NLFC processing.

CONCLUSION

Overall, the adaptive NLFC processing evaluated in this study has the potential to significantly improve speech perception relative to conventional NLFC processing.

Intracochlear Recordings of Acoustically and Electrically Evoked Potentials in Nucleus Hybrid L24 Cochlear Implant Users and Their Relationship to Speech Perception

The Hybrid cochlear implant (CI) has been developed for individuals with high frequency hearing loss who retain good low frequency hearing. Outcomes have been encouraging but individual variability is high; the health of the cochlea and the auditory nerve may be important factors driving outcomes. Electrically evoked compound action potentials (ECAPs) reflect the response of the auditory nerve to electrical stimulation while electrocochleography (ECochG) reflects the response of the cochlear hair cells and auditory nerve to acoustic stimulation. In this study both ECAPs and ECochG responses were recorded from Nucleus Hybrid L24 CI users. Correlations between these two measures of peripheral auditory function and speech perception are reported. This retrospective study includes data from 25 L24 CI users. ECAPs and ECochG responses were recorded from an intracochlear electrode using stimuli presented at or near maximum acceptable loudness levels. Speech perception was assessed using Consonant-Nucleus-Consonant (CNC) word lists presented in quiet and AzBio sentences presented at a +5 dB signal-to-noise ratio in both the combined acoustic and electric (A+E) and electric (E) alone listening modes. Acoustic gain was calculated by subtracting these two scores. Correlations between these physiologic and speech perception measures were then computed. ECAP amplitudes recorded from the most apical electrode were significantly correlated with CNC scores measured in the E alone (r = 0.56) and A+E conditions (r = 0.64), but not with performance on the AzBio test. ECochG responses recorded using the most apical electrode in the intracochlear array but evoked using a 500 Hz tone burst were not correlated with either the scores on the CNC or AzBio tests. However, ECochG amplitude was correlated with a composite metric relating the additional benefit of acoustic gain in noise relative to quiet conditions (r = 0.67). Both measures can be recorded from Hybrid L24 CI users and both ECAP and ECochG measures may result in more complete characterization of speech perception outcomes than either measure alone.

Associations between the probabilities of frequency-specific hearing loss and unaided APHAB scores

The Abbreviated Profile of Hearing Aid Benefit (APHAB) questionnaire reports subjective hearing impairments in four typical conditions. We investigated the association between the frequency-specific probability of hearing loss and scores from the unaided APHAB (APHAB_u) to determine whether the APHAB_u could be useful in primary diagnoses of hearing loss, in addition to pure tone and speech audiometry. This retrospective study included database records from 6558 patients (average age 69.0 years). We employed a multivariate generalised linear mixed model to analyse the probabilities of hearing losses (severity range 20–75 dB, evaluated in 5-dB steps), measured at different frequencies (0.5, 1.0, 2.0, 4.0, and 8.0 kHz), for nearly all combinations of APHAB_u subscale scores (subscale scores from 20 to 80%, evaluated in steps of 5%). We calculated the probability of hearing loss for 28,561 different combinations of APHAB_u subscale scores (results available online). In general, the probability of hearing loss was positively associated with the combined APHAB_u score (i.e. increasing probability with increasing scores). However, this association was negative at one frequency (8 kHz). The highest probabilities were for a hearing loss of 45 dB at test frequency 2.0 kHz, but with a wide spreading. We showed that the APHAB_u subscale scores were associated with the probability of hearing loss measured with audiometry. This information could enrich the expert’s evaluation of the subject’s hearing loss, and it might help resolve suspicious cases of aggravation. The 0.5 and 8.0 kHz frequencies influenced hearing loss less than the frequencies in-between, and 2.0 kHz was most influential on intermediate degree hearing loss (around 45 dB), which corresponded to the frequency-dependence of speech intelligibility measured with speech audiometry.

Multicenter clinical trial of the Nucleus Hybrid S8 cochlear implant: Final outcomes

OBJECTIVES/HYPOTHESIS

The concept of expanding electrical speech processing to those with more residual acoustic hearing with a less-invasive shorter cochlear implant (CI) has been ongoing since 1999. A multicenter study of the Nucleus Hybrid S8 CI took place between 2002 and 2011. This report describes the final outcomes of this clinical trial.

STUDY DESIGN

Multicenter, longitudinal, single-subject design.

METHODS

Eighty-seven subjects received a Nucleus Hybrid S8 CI in their poorer ear. Speech perception in quiet (Consonant-Nucleus-Consonant [CNC] words) and in noise (Bamford-Kowal-Bench Sentences-In-Noise [BKB-SIN]) were collected pre- and postoperatively at 3, 6, and 12 months. Subjective questionnaire data using the Abbreviated Profile for Hearing Aid Benefit (APHAB) were also collected.

RESULTS

Some level of hearing preservation was accomplished in 98% subjects, with 90% maintaining a functional low-frequency pure-tone average (LFPTA) at initial activation. By 12 months, five subjects had total hearing loss, and 80% of subjects maintained functional hearing. CNC words demonstrated that 82.5% and 87.5% of subjects had significant improvements in the hybrid and combined conditions, respectively. The majority had improvements with BKB-SIN. Results also indicated that as long as subjects maintained at least a severe LFPTA, there was significant improvement in speech understanding. Furthermore, all subjects reported positive improvements in hearing in three of the four subscales of the APHAB.

CONCLUSIONS

The concept of hybrid speech processing has significant advantages for subjects with residual low-frequency hearing. In this study, the Nucleus Hybrid S8 provided improved word understanding in quiet and noise. Additionally, there appears to be stability of the residual hearing after initial activation of the device.

LEVEL OF EVIDENCE

2c.

The effect of presentation level on spectral weights for sentences

Psychophysical data indicate that spectral weights tend to increase with increasing presentation level at high frequencies. The present study examined whether spectral weights for speech perception are similarly affected by presentation level. Stimuli were sentences filtered into five contiguous frequency bands and presented at each of two levels (75 and 95 dB sound pressure level [SPL]). For the highest band (2807-10,000 Hz), normal-hearing listeners' weights were higher for the higher presentation level. Weights for the 95-dB-SPL level resembled those previously estimated for hearing-impaired listeners tested at comparably high levels, suggesting that hearing loss itself may not play a large role in spectral weighting for a sentence recognition task.

Hearing preservation among patients undergoing cochlear implantation

INTRODUCTION

Despite successful preservation of low-frequency hearing in patients undergoing cochlear implantation (CI) with shorter electrode lengths, there is still controversy regarding which electrodes maximize hearing preservation (HP). The thin straight electrode array (TSEA) has been suggested as a full cochlear coverage option for HP. However, very little is known regarding its HP potential.

METHODS

A retrospective review was performed at two tertiary academic medical centers, reviewing the electronic records for 52 patients (mean, 58.2 yr; range, 11-85 yr) implanted with the Cochlear Nucleus CI422 Slim Straight (Centennial, CO, USA) electrode array, referred to herein as the thin straight electrode array or TSEA. All patients had a preoperative low-frequency pure-tone average (LFPTA) of 85 dB HL or less. Hearing thresholds were measured at initial activation (t1) and 6 months after activation (t2). HP was assessed by evaluating functional HP using a cutoff level of 85 dB HL PTA.

RESULTS

At t1, 54% of the subjects had functional hearing; 33% of these subjects had an LFPTA between 71 and 85 dB HL, and 17% had an LFPTA between 56 and 70 dB HL. At t2, 47% of the patients had functional hearing, with 31% having an LFPTA between 71 and 85 dB HL.

DISCUSSION

Preliminary research suggests that the TSEA has the potential to preserve functional hearing in 54% of patients at t1. However, 22% (n = 6) of the patients who had functional hearing at t1 (n = 28) lost their hearing between t1 and t2. Further studies are needed to evaluate factors that influence HP with the TSEA electrode and determine the speech perception benefits using electric and acoustic hearing over electric alone.

United States multicenter clinical trial of the cochlear nucleus hybrid implant system

Objectives/Hypothesis

To evaluate the safety and efficacy of acoustic and electric sound processing for individuals with significant residual low‐frequency hearing and severe‐to‐profound high‐frequency sensorineural hearing loss.

Study Design

Prospective, single‐arm repeated measures, single‐subject design.

Methods

Fifty individuals, ≥ 18 years old, with low‐frequency hearing and severe high‐frequency loss were implanted with the Cochlear Nucleus Hybrid L24 implant at 10 investigational sites. Preoperatively, subjects demonstrated consonant‐nucleus‐consonant word scores of 10% through 60% in the ear to be implanted. Subjects were assessed prospectively, preoperatively, and postoperatively on coprimary endpoints of consonant‐nucleus‐consonant words, AzBio sentences in noise, and self‐assessment measures.

Results

Significant mean improvements were observed for coprimary endpoints: consonant‐nucleus‐consonant words (35.8 percentage points) and AzBio sentences in noise (32.0 percentage points), both at P < 0.001. Ninety‐six percent of subjects performed equal or better on speech in quiet and 90% in noise. Eighty‐two percent of subjects showed improved performance on speech in quiet and 74% in noise. Self‐assessments were positive, corroborating speech perception results.

Conclusion

The Nucleus Hybrid System provides significant improvements in speech intelligibility in quiet and noise for individuals with severe high‐frequency loss and some low‐frequency hearing. This device expands indications to hearing‐impaired individuals who perform poorly with amplification due to bilateral high‐frequency hearing loss and who previously were not implant candidates.

Level of Evidence

2b. Laryngoscope, 126:175–181, 2016

The importance of high-frequency audibility with and without visual cues on speech recognition for listeners with normal hearing

OBJECTIVE

To examine the impact of visual cues, speech materials, age and listening condition on the frequency bandwidth necessary for optimizing speech recognition performance.

DESIGN

Using a randomized repeated measures design; speech recognition performance was assessed using four speech perception tests presented in quiet and noise in 13 LP filter conditions and presented in multimodalities. Participants' performance data were fitted with a Boltzmann function to determine optimal performance (10% below performance achieved in FBW).

STUDY SAMPLE

Thirty adults (18-63 years) and thirty children (7-12 years) with normal hearing.

RESULTS

Visual cues significantly reduced the bandwidth required for optimizing speech recognition performance for listeners. The type of speech material significantly impacted the bandwidth required for optimizing performance. Both groups required significantly less bandwidth in quiet, although children required significantly more than adults. The widest bandwidth required was for the phoneme detection task in noise where children required a bandwidth of 7399 Hz and adults 6674 Hz.

CONCLUSIONS

Listeners require significantly less bandwidth for optimizing speech recognition performance when assessed using sentence materials with visual cues. That is, the amount of bandwidth systematically decreased as a function of increased contextual, linguistic, and visual content.

Listening Comprehension in Middle-Aged Adults

PURPOSE

The purpose of this summary is to examine changes in listening comprehension across the adult lifespan and to identify factors associated with individual differences in listening comprehension.

METHOD

In this article, the author reports on both cross-sectional and longitudinal changes in listening comprehension.

CONCLUSIONS

Despite significant declines in both sensory and cognitive abilities, listening comprehension remains relatively unchanged in middle-aged listeners (between the ages of 40 and 60 years) compared with young listeners. These results are discussed with respect to possible compensatory factors that maintain listening comprehension despite impaired hearing and reduced cognitive capacities.

Cochlear dead regions constrain the benefit of combining acoustic stimulation with electric stimulation

OBJECTIVE

The aims of this study were to (1) detect the presence and edge frequency (fe) of a cochlear dead region in the ear with residual acoustic hearing for bimodal cochlear implant users, and (2) determine whether amplification based on the presence or absence of a dead region would improve speech understanding and sound quality.

DESIGN

Twenty-two listeners with a cochlear implant in one ear and residual acoustic hearing in the nonimplanted ear were tested. Eleven listeners had a cochlear dead region in the acoustic-hearing ear and 11 did not. Dead regions were assessed with the threshold-equalizing noise (TEN) and the sweeping noise, psychophysical tuning curve tests. Speech understanding was assessed with monosyllabic words and the AzBio sentences at +10 dB signal-to-noise ratio. Speech- and music-quality judgments were obtained with the Judgment of Sound Quality questionnaire.

RESULTS

Using shifted tips of the psychophysical tuning curve as a basis for diagnosis, the TEN had high sensitivity (0.91) and poor specificity (0.55) for this population. The value of fe was lower when estimated with the sweeping noise, psychophysical tuning curve test than with the TEN test. For the listeners with cochlear dead regions, speech understanding, speech quality and music quality were best when no amplification was applied for frequencies within the dead region. For listeners without dead regions, speech understanding was best with full-bandwidth amplification and was reduced when amplification was not applied when the audiometric threshold exceeded 80 dB HL.

CONCLUSION

The data from this study suggest that, to improve bimodal benefit for listeners who combine electric and acoustic stimulation, audiologists should routinely test for the presence of cochlear dead regions and determine amplification bandwidth accordingly.

Spatial separation benefit for unaided and aided listening

OBJECTIVES

The benefit attributable to spatial separation of speech and noise was measured as a function of low-pass cutoff frequency with and without bilateral hearing aids.

DESIGN

Fourteen younger and 10 older adults with normal hearing and 12 older adults with mild-to-moderate sloping high frequency hearing loss were included to assess the effects of age and hearing loss. Subjects with hearing loss were provided commercially available bilateral hearing aids. Consonant recognition was measured at 70 dB SPL in a background of speech-shaped noise at 66 dB SPL. Speech and noise were low-pass filtered at 1.7, 3.4, and 7.1 kHz. Nonsense syllables were always at 0° and noise was at either 0° or 90°. Speech and noise spectra for all conditions were digitally recorded using a probe microphone placed in each ear canal of each subject. Spectra and levels of speech, and quiet thresholds for narrowband noises, were used to calculate the Articulation Index and provide predictions of unaided and aided (hearing-impaired only) consonant recognition, spatial benefit, and hearing aid benefit for each condition. Subjective ratings of workload (NASA Task Load Index) were obtained for all unaided and aided measures of speech recognition.

RESULTS

Consonant recognition in noise improved for all groups with speech and noise spatially separated and with the addition of high-frequency speech information. Scores were poorer overall for the older adults with hearing loss than for the other groups. For normal-hearing subjects, observed scores and spatial benefit were better than predicted. For hearing-impaired subjects, scores did not significantly improve with hearing aids, even with higher frequencies and spatial separation, and were poorer than predicted especially for aided listening. Similar to subjects with normal hearing, spatial benefit for hearing-impaired subjects was larger than predicted.

CONCLUSIONS

Younger and older adults with normal hearing benefited from spatial separation of speech and noise sources to a greater extent than predicted based on simple audibility. Thus, no age-related deficits in the use of interaural difference cues were observed. Although hearing aid benefit was negligible, perceived listening effort was lower aided than unaided, especially with spatial separation. Articulation Index predictions revealed that speech audibility was generally restored with hearing aids across a wide bandwidth of speech, especially in the far ear. Thus, reduced audibility was not a primary factor in limited hearing aid benefit, suggesting that peripheral, central-auditory and/or cognitive changes may have played a role. In contrast, unaided and aided spatial benefit was better than predicted, and spatial benefit was slightly larger with hearing aids than without. Thus, these older adults with hearing loss using bilateral hearing aids were able to take advantage of binaural cues to improve consonant recognition in noise.

Estudo do reconhecimento de fala nas perdas auditivas neurossensoriais descendentes

Objetivo verificar quais aspectos da configuração audiométrica influenciam a discriminação de fala nas perdas auditivas neurossensoriais descendentes. Métodos foi realizado um levantamento de prontuários hospitalar dos pacientes atendidos no Serviço de Atenção à Saúde Auditiva, no período de março a julho de 2011, selecionando-se indivíduos com perdas auditivas neurossensoriais descendentes de grau leve a severo com idade superior a 18 anos. A perda auditiva foi considerada descendente quando a diferença entre as médias das frequências de 0,25 a 2 kHz e 3 a 8 kHz foi maior que 15 dBNA. A partir deste levantamento a amostra do estudo foi composta por 30 pacientes (55 orelhas) sendo 19 homens e 11 mulheres, com idades compreendidas entre 26 e 91 anos. Com base na avaliação audiológica realizada previamente, os testes de reconhecimento de fala foram correlacionados com diferentes médias de limiares tonais, incluindo as frequências de 0,5 a 4 kHz. Além disso, estudou-se as diferenças dos limiares auditivos tonais entre oitavas de frequências, ou seja, o grau de inclinação das curvas audiométricas, e o seu impacto na discriminação de fala. Resultados encontrou-se ótima correlação entre os limiares médios de 0,5 a 4 kHz com a discriminação de fala, sendo essa correlação mais forte com a inclusão das frequências de 3 e 4 kHz na média tonal. No entanto, o aumento da diferença do limiar auditivo entre as oitavas de frequências, que implica em uma maior inclinação da curva audiométrica com queda acentuada nas frequências altas, não interferiu de forma significante nos testes de reconhecimento de fala. Conclusão com base nos resultados deste estudo, pode-se concluir que as frequências de 3 e 4 kHz contribuem para a inteligibilidade de fala.

Techniques to improve the efficiency of a middle ear implant: effect of different methods of coupling to the ossicular chain

HYPOTHESIS

Coupling and placement of actuators onto the ossicular chain have a significant influence on active middle ear implant (AMEI) performance.

BACKGROUND

AMEIs have proved to be effective in treating moderate-to-severe sensorineural hearing loss as well as mixed and conductive loss. Here, we assess the effect on performance of an AMEI prosthesis using 5 different methods of coupling to the ossicular chain in 6 temporal bones.

METHODS

The AMEI provided direct vibratory stimuli to the incus using the following methods: 1) tip of the transducer in contact with incus body (baseline condition), 2) tip of the transducer placed in a laser-drilled hole in the incus body, 3) the àWengen clips (straight and articulated) crimped to the transducer and attached to the incus long process, 4) a 0.5-mm diameter cylinder placed in contact with the incus long process, and 5) a bell-shaped prosthesis in contact with the head of the stapes. Performance in each condition was assessed by measuring the resultant stapes velocities (HEV) from which the maximum equivalent ear canal sound pressure levels (L(Emax)) were computed.

RESULTS

Relative to the baseline condition, which produced L(Emax) of 112 to 126 dB SPL for frequencies of 0.25 to 8 kHz, the other coupling methods produced similar or substantially improved (increased L(Emax)) performance. Best performance was achieved by providing vibratory stimulation to the head of the stapes directly with the bell-shaped tip where performance improved significantly by 16 to 22 dB.

CONCLUSION

Stapes velocities produced by AMEI transducers may be increased depending on the tip used to couple the transducer to the ossicular chain and the placement of the stimulating tip along the incus. Improvement in coupling the transducer to the incus and stapes produced significant improvements in the transfer of vibratory stimuli to the ossicular chain.

Speech identification with temporal and spectral modification in subjects with auditory neuropathy

Background. The aim of this study was to investigate the individual effects of envelope enhancement and high-pass filtering (500 Hz) on word identification scores in quiet for individuals with Auditory Neuropathy. Method. Twelve individuals with Auditory Neuropathy (six males and six females) with ages ranging from 12 to 40 years participated in the study. Word identification was assessed using bi-syllabic words in each of three speech processing conditions: unprocessed, envelope-enhanced, and high-pass filtered. All signal processing was carried out using MATLAB-7. Results. Word identification scores showed a mean improvement of 18% with envelope enhanced versus unprocessed speech. No significant improvement was observed with high-pass filtered versus unprocessed speech. Conclusion. These results suggest that the compression/expansion signal processing strategy enhances speech identification scores-at least for mild and moderately impaired individuals with AN. In contrast, simple high-pass filtering (i.e., eliminating the low-frequency content of the signal) does not improve speech perception in quiet for individuals with Auditory Neuropathy.

Listening comprehension across the adult lifespan

OBJECTIVES

Although age-related declines in perceiving spoken language are well established, the primary focus of research has been on perception of phonemes, words, and sentences. In contrast, relatively few investigations have been directed at establishing the effects of age on the comprehension of extended spoken passages. Moreover, most previous work has used extreme-group designs in which the performance of a group of young adults is contrasted with that of a group of older adults and little if any information is available regarding changes in listening comprehension across the adult lifespan. Accordingly, the goals of the current investigation were to determine whether there are age differences in listening comprehension across the adult lifespan and, if so, whether similar trajectories are observed for age-related changes in auditory sensitivity and listening comprehension.

DESIGN

This study used a cross-sectional lifespan design in which approximately 60 individuals in each of 7 decades, from age 20 to 89 yr (a total of 433 participants), were tested on three different measures of listening comprehension. In addition, we obtained measures of auditory sensitivity from all participants.

RESULTS

Changes in auditory sensitivity across the adult lifespan exhibited the progressive high-frequency loss typical of age-related hearing impairment. Performance on the listening comprehension measures, however, demonstrated a very different pattern, with scores on all measures remaining relatively stable until age 65 to 70 yr, after which significant declines were observed. Follow-up analyses indicated that this same general pattern was observed across three different types of passages (lectures, interviews, and narratives) and three different question types (information, integration, and inference). Multiple regression analyses indicated that low-frequency pure-tone average was the single largest contributor to age-related variance in listening comprehension for individuals older than 65 yr, but that age accounted for significant variance even after controlling for auditory sensitivity.

CONCLUSIONS

Results suggest that age-related reductions in auditory sensitivity account for a sizable portion of individual variance in listening comprehension that was observed across the adult lifespan. Other potential contributors including a possible role for age-related declines in perceptual and cognitive abilities are discussed. Clinically, the results suggest that amplification is likely to improve listening comprehension but that increased audibility alone may not be sufficient to maintain listening comprehension beyond age 65 and 70 yr. Additional research will be needed to identify potential target abilities for training or other rehabilitation procedures that could supplement sensory aids to provide additional improvements in listening comprehension.

Effects of degree and configuration of hearing loss on the contribution of high- and low-frequency speech information to bilateral speech understanding

OBJECTIVES

The purpose of this study was to examine the effects of degree and configuration of hearing loss on the use of, and benefit from, information in amplified high- and low-frequency speech presented in background noise.

DESIGN

Sixty-two adults with a wide range of high- and low-frequency sensorineural hearing loss (5 to 115+ dB HL) participated in the study. To examine the contribution of speech information in different frequency regions, speech understanding in noise was assessed in multiple low- and high-pass filter conditions, as well as a band-pass (713 to 3534 Hz) and wideband (143 to 8976 Hz) condition. To increase audibility over a wide frequency range, speech and noise were amplified based on each individual's hearing loss. A stepwise multiple linear regression approach was used to examine the contribution of several factors to (1) absolute performance in each filter condition and (2) the change in performance with the addition of amplified high- and low-frequency speech components.

RESULTS

Results from the regression analysis showed that degree of hearing loss was the strongest predictor of absolute performance for low- and high-pass filtered speech materials. In addition, configuration of hearing loss affected both absolute performance for severely low-pass filtered speech and benefit from extending high-frequency (3534 to 8976 Hz) bandwidth. Specifically, individuals with steeply sloping high-frequency losses made better use of low-pass filtered speech information than individuals with similar low-frequency thresholds but less high-frequency loss. In contrast, given similar high-frequency thresholds, individuals with flat hearing losses received more benefit from extending high-frequency bandwidth than individuals with more sloping losses.

CONCLUSIONS

Consistent with previous work, benefit from speech information in a given frequency region generally decreases as degree of hearing loss in that frequency region increases. However, given a similar degree of loss, the configuration of hearing loss also affects the ability to use speech information in different frequency regions. Except for individuals with steeply sloping high-frequency losses, providing high-frequency amplification (3534 to 8976 Hz) had either a beneficial effect on, or did not significantly degrade, speech understanding. These findings highlight the importance of extended high-frequency amplification for listeners with a wide range of high-frequency hearing losses, when seeking to maximize intelligibility.

Speech reception by listeners with real and simulated hearing impairment: effects of continuous and interrupted noise

The effects of audibility and age on masking for sentences in continuous and interrupted noise were examined in listeners with real and simulated hearing loss. The absolute thresholds of each of ten listeners with sensorineural hearing loss were simulated in normal-hearing listeners through a combination of spectrally-shaped threshold noise and multi-band expansion for octave bands with center frequencies from 0.25-8 kHz. Each individual hearing loss was simulated in two groups of three normal-hearing listeners (an age-matched and a non-age-matched group). The speech-to-noise ratio (S/N) for 50%-correct identification of hearing in noise test (HINT) sentences was measured in backgrounds of continuous and temporally-modulated (10 Hz square-wave) noise at two overall levels for unprocessed speech and for speech that was amplified with the NAL-RP prescription. The S/N in both continuous and interrupted noise of the hearing-impaired listeners was relatively well-simulated in both groups of normal-hearing listeners. Thus, release from masking (the difference in S/N obtained in continuous versus interrupted noise) appears to be determined primarily by audibility. Minimal age effects were observed in this small sample. Observed values of masking release were compared to predictions derived from intelligibility curves generated using the extended speech intelligibility index (ESII) [Rhebergen et al. (2006). J. Acoust. Soc. Am. 120, 3988-3997].

Effect of spatial separation, extended bandwidth, and compression speed on intelligibility in a competing-speech task

The benefit for speech intelligibility of extending the bandwidth of hearing aids was assessed when the target speech (sentences) and background (two talkers) were co-located or spatially separated. Also, the relative benefits of slow and fast compression were assessed. Sixteen hearing-impaired (HI) subjects with mild-to-moderate high-frequency hearing loss and eight normal-hearing (NH) subjects were tested. The target and interfering sounds were recorded using a KEMAR manikin and were located at +/-60 degrees azimuth, either co-located or spatially separated. Simulated binaural hearing-aid processing using five-channel slow or fast compression was performed offline, with gains set individually for each HI subject. Upper cutoff frequencies were 5, 7.5, or 10 kHz. Processed stimuli were presented via headphones. For both NH (unaided) and HI subjects, there was no significant effect of cutoff frequency for the co-located condition, but a small but significant benefit from increasing the cutoff frequency from 5 to 7.5 kHz for the spatially separated condition. For the HI subjects, slow compression gave slightly but significantly higher scores than fast compression for the spatially separated but not for the co-located condition. There were marked individual differences both in the benefit from extended bandwidth and in the relative benefit of slow and fast compression.

Modeling speech intelligibility in quiet and noise in listeners with normal and impaired hearing

The speech intelligibility index (SII) is an often used calculation method for estimating the proportion of audible speech in noise. For speech reception thresholds (SRTs), measured in normally hearing listeners using various types of stationary noise, this model predicts a fairly constant speech proportion of about 0.33, necessary for Dutch sentence intelligibility. However, when the SII model is applied for SRTs in quiet, the estimated speech proportions are often higher, and show a larger inter-subject variability, than found for speech in noise near normal speech levels [65 dB sound pressure level (SPL)]. The present model attempts to alleviate this problem by including cochlear compression. It is based on a loudness model for normally hearing and hearing-impaired listeners of Moore and Glasberg [(2004). Hear. Res. 188, 70-88]. It estimates internal excitation levels for speech and noise and then calculates the proportion of speech above noise and threshold using similar spectral weighting as used in the SII. The present model and the standard SII were used to predict SII values in quiet and in stationary noise for normally hearing and hearing-impaired listeners. The present model predicted SIIs for three listener types (normal hearing, noise-induced, and age-induced hearing loss) with markedly less variability than the standard SII.