Targeting the psychosocial and functional fitness challenges of older adults with hearing loss: a participatory approach to adaptation of the walk and talk for your life program.

OBJECTIVE: Explore the acceptability of a socialisation, health education and falls prevention programme (Walk and Talk for Your Life: WTL) as an adjunct to group auditory rehabilitation (GAR) and how it might be adapted for older adults with hearing loss (HL). DESIGN: Content theme analysis (CTA) of guided interviews explored the experience of HL, the acceptability of a WTL programme and suggestions on how to adapt the WTL programme to better suit the needs of older adults with HL. STUDY SAMPLE: Twenty-eight (20 women, 8 men) adults (>55 years of age) with HL were interviewed. Seventeen had participated in past WTL programmes and eleven were sampled from the community. RESULTS: Interviewees reported difficulty socialising and a tendency to withdraw from social interactions. Addition of GAR to a WTL programme was found to be highly acceptable. Interviewees suggested that to best suit their needs, sessions should take place in a location with optimal acoustics; include small groups integrating hearing-impaired and hearing-intact participants; include appropriate speaking ground rules; and include an option for partner involvement. CONCLUSIONS: The adapted WTL programme provides a holistic and unique approach to the treatment of HL that has the potential to positively impact the hearing-impaired elderly.

Hearing impairment, cognition and speech understanding: exploratory factor analyses of a comprehensive test battery for a group of hearing aid users, the n200 study.

OBJECTIVE: The aims of the current n200 study were to assess the structural relations between three classes of test variables (i.e. HEARING, COGNITION and aided speech-in-noise OUTCOMES) and to describe the theoretical implications of these relations for the Ease of Language Understanding (ELU) model. STUDY SAMPLE: Participants were 200 hard-of-hearing hearing-aid users, with a mean age of 60.8 years. Forty-three percent were females and the mean hearing threshold in the better ear was 37.4 dB HL. DESIGN: LEVEL1 factor analyses extracted one factor per test and/or cognitive function based on a priori conceptualizations. The more abstract LEVEL 2 factor analyses were performed separately for the three classes of test variables. RESULTS: The HEARING test variables resulted in two LEVEL 2 factors, which we labelled SENSITIVITY and TEMPORAL FINE STRUCTURE; the COGNITIVE variables in one COGNITION factor only, and OUTCOMES in two factors, NO CONTEXT and CONTEXT. COGNITION predicted the NO CONTEXT factor to a stronger extent than the CONTEXT outcome factor. TEMPORAL FINE STRUCTURE and SENSITIVITY were associated with COGNITION and all three contributed significantly and independently to especially the NO CONTEXT outcome scores (R(2) = 0.40). CONCLUSIONS: All LEVEL 2 factors are important theoretically as well as for clinical assessment.

Perception of hearing impairment and the willingness to use hearing aids in an elderly population in southern Taiwan: A community-based study.

OBJECTIVES: To estimate the prevalence and severity of hearing impairment (HI), the self-perception of HI, and the willingness to use a hearing aid (HA) in the elderly population in southern Taiwan. DESIGN: This community-based study was performed in a metropolitan hospital. A questionnaire about the perception of HI and the willingness to use a HA was used. The severity of HI in speech-frequency pure-tone average (PTA) was evaluated. The associations between sex, age, severity of HI, self-perception of HI, and the willingness to use a HA were analysed. STUDY SAMPLE: A total of 599 volunteers were recruited from the health management center; 324 (54.1%) males and 275 (45.9%) females, who were 65 years of age or older. RESULTS: The prevalence of HI >25 dBHL in the elderly was 78%. The predicted levels for elderly persons to perceive HI and hearing difficulties were 34.38 dBHL and 54.38 dBHL, respectively. Males and younger participants were more willing to use HA. The primary reasons for refusing HA use were discomfort (25.1%) and a self-perception that the HA was unnecessary (19.7%). CONCLUSIONS: The prevalence of HI was high among the elderly population in southern Taiwan. Age and sex were the determinants of HA use.

Hearing-aid use and its determinants in the UK National Health Service: a cross-sectional study at the Royal Surrey County Hospital.

OBJECTIVES: The aim of this study was to investigate the rate of and factors contributing to non-adherence to hearing-aid use in the UK National Health Service. DESIGN: A cross-sectional postal questionnaire survey. STUDY SAMPLE: A questionnaire, including the International Outcome Inventory for Hearing Aids, was sent to all patients fitted with hearing aids at the Royal Surrey County Hospital between 2011 and 2012 (N = 1874). A total of 1023 questionnaires were completed and returned (response rate of 55%). RESULTS: A total of 29% of responders did not use their hearing aids on a regular basis (i.e. used them less than four hours per day). Non-regular use was more prevalent in new (40%) than in existing patients (11%). Factors that reduced the risk of non-regular use included bilateral versus unilateral amplification, and moderate or severe hearing loss in the better ear. 16% of responders fitted with bilateral amplification used only one of their hearing aids. CONCLUSIONS: The level of non-regular use of hearing aids in NHS found in this study was comparable to those for other countries. Additional support might be needed for patients at a higher risk of non-regular use.

Music mixing preferences of cochlear implant recipients: a pilot study.

OBJECTIVE: Music perception and appraisal are generally poor in cochlear implant recipients. Simple musical structures, lyrics that are easy to follow, and clear rhythm/beat have been reported among the top factors to enhance music enjoyment. The present study investigated the preference for modified relative instrument levels in music with normal-hearing and cochlear implant subjects. DESIGN: In experiment 1, test subjects were given a mixing console and multi-track recordings to determine their most enjoyable audio mix. In experiment 2, a preference rating experiment based on the preferred relative level settings in experiment 1 was performed. STUDY SAMPLE: Experiment 1 was performed with four postlingually deafened cochlear implant subjects, experiment 2 with ten normal-hearing and ten cochlear implant subjects. RESULTS: A significant difference in preference rating was found between normal-hearing and cochlear implant subjects. The latter preferred an audio mix with larger vocals-to-instruments ratio. In addition, given an audio mix with clear vocals and attenuated instruments, cochlear implant subjects preferred the bass/drum track to be louder than the other instrument tracks. CONCLUSIONS: The original audio mix in real-world music might not be suitable for cochlear implant recipients. Modifying the relative instrument level settings potentially improves music enjoyment.

Rate and onset cues can improve cochlear implant synthetic vowel recognition in noise.

Understanding speech-in-noise is difficult for most cochlear implant (CI) users. Speech-in-noise segregation cues are well understood for acoustic hearing but not for electric hearing. This study investigated the effects of stimulation rate and onset delay on synthetic vowel-in-noise recognition in CI subjects. In experiment I, synthetic vowels were presented at 50, 145, or 795 pulse/s and noise at the same three rates, yielding nine combinations. Recognition improved significantly if the noise had a lower rate than the vowel, suggesting that listeners can use temporal gaps in the noise to detect a synthetic vowel. This hypothesis is supported by accurate prediction of synthetic vowel recognition using a temporal integration window model. Using lower rates a similar trend was observed in normal hearing subjects. Experiment II found that for CI subjects, a vowel onset delay improved performance if the noise had a lower or higher rate than the synthetic vowel. These results show that differing rates or onset times can improve synthetic vowel-in-noise recognition, indicating a need to develop speech processing strategies that encode or emphasize these cues.

Multichannel compression hearing aids: effect of channel bandwidth on consonant and vowel identification by hearing-impaired listeners.

Aided consonant and vowel identification was measured in 13 listeners with high-frequency sloping hearing losses. To investigate the influence of compression-channel analysis bandwidth on identification performance independent of the number of channels, performance was compared for three 17-channel compression systems that differed only in terms of their channel bandwidths. One compressor had narrow channels, one had widely overlapping channels, and the third had level-dependent channels. Measurements were done in quiet, in speech-shaped noise, and in a three-talker background. The results showed no effect of channel bandwidth, neither on consonant nor on vowel identification scores. This suggests that channel bandwidth per se has little influence on speech intelligibility when individually prescribed, frequency-varying compressive gain is provided.

Comparison of two channel selection criteria for noise suppression in cochlear implants.

The performance of current channel selection criteria used in cochlear implant (CI) devices (e.g., maximum selection criterion used in ACE) degrades significantly in the presence of noise. In noisy backgrounds, coding strategies that select the "right" channels for stimulation could potentially produce substantial improvements in intelligibility. In this study, the performance of two alternative channel selection criteria is assessed in terms of intelligibility and subjective quality with CI users in noise. The performance is compared against that of the maximum selection scheme employed in the ACE strategy (comparison is also made with the CIS strategy). Sentences were presented to seven CI users in speech weighted noise (-5, 0, and 5 dB SNR). Both channel selection criteria were implemented under ideal conditions where a priori knowledge of the target and masker was assumed. This was done to assess the full potential benefit of selecting the "right" channels for stimulation in noisy backgrounds. Substantial intelligibility improvement relative to the CI users' daily strategy (i.e., ACE or CIS) was achieved with the two different channel selection criteria under all noisy conditions considered. No significant difference in subjective quality of noisy speech processed by the two channel selection criteria was observed.

Blind binary masking for reverberation suppression in cochlear implants.

A monaural binary time-frequency (T-F) masking technique is proposed for suppressing reverberation. The mask is estimated for each T-F unit by extracting a variance-based feature from the reverberant signal and comparing it against an adaptive threshold. Performance of the estimated binary mask is evaluated in three moderate to relatively high reverberant conditions (T60 = 0.3, 0.6, and 0.8 s) using intelligibility listening tests with cochlear implant users. Results indicate that the proposed T-F masking technique yields significant improvements in intelligibility of reverberant speech even in relatively high reverberant conditions (T60 = 0.8 s). The improvement is hypothesized to result from the recovery of the vowel/consonant boundaries, which are severely smeared in reverberation.

Mapping procedures can produce non-centered auditory images in bilateral cochlear implantees.

Good localization accuracy depends on an auditory spatial map that provides consistent binaural information across frequency and level. This study investigated whether mapping bilateral cochlear implants (CIs) independently contributes to distorted perceptual spatial maps. In a meta-analysis, interaural level differences necessary to perceptually center sound images were calculated for 127 pitch-matched pairs of electrodes; many needed large current adjustments to be perceptually centered. In a separate experiment, lateralization was also found to be inconsistent across levels. These findings suggest that auditory spatial maps are distorted in the mapping process, which likely reduces localization accuracy and target-noise separation in bilateral CIs.

Speech perception in simulated electric hearing exploits information-bearing acoustic change.

Stilp and Kluender [(2010). Proc. Natl. Acad. Sci. U.S.A. 107(27), 12387-12392] reported measures of sensory change over time (cochlea-scaled spectral entropy, CSE) reliably predicted sentence intelligibility for normal-hearing listeners. Here, implications for listeners with atypical hearing were explored using noise-vocoded speech. CSE was parameterized as Euclidean distances between biologically scaled spectra [measured before sentences were noise vocoded (CSE)] or between channel amplitude profiles in simulated cochlear-implant processing [measured after vocoding (CSE(CI))]. Sentence intelligibility worsened with greater amounts of information replaced by noise; patterns of performance did not differ between CSE and CSE(CI). Results demonstrate the importance of information-bearing change for speech perception in simulated electric hearing.

Masking patterns for monopolar and phantom electrode stimulation in cochlear implants.

Phantom electrode (PE) stimulation consists of out-of-phase stimulation of two electrodes. When presented at the apex of the electrode array, phantom stimulation is known to produce a lower pitch sensation than monopolar (MP) stimulation on the most apical electrode. The ratio of the current between the primary electrode (PEL) and the compensating electrode (CEL) is represented by the coefficient σ, which ranges from 0 (monopolar) to 1 (full bipolar). The exact mechanism by which PE stimulation produces a lower pitch sensation is unclear. In the present study, unmasked and masked thresholds were obtained using a forward masking paradigm to estimate the spread of current for MP and PE stimulation. Masked thresholds were measured for two phantom electrode configurations (1) PEL = 4, CEL = 5 (lower pitch phantom) and (2) PEL = 4, CEL = 3 (higher pitch phantom). The unmasked thresholds were subtracted from the masked thresholds to obtain masking patterns which were normalized to their peak. The masking patterns reveal (1) differences in the spread of excitation that are consistent with the direction of pitch shift produced by PE stimulation, and (2) narrower spread of electrical excitation for PE stimulation relative to MP stimulation.

Detection of acoustic temporal fine structure by cochlear implant listeners: behavioral results and computational modeling.

A test of within-channel detection of acoustic temporal fine structure (aTFS) cues is presented. Eight cochlear implant listeners (CI) were asked to discriminate between two Schroeder-phase (SP) complexes using a two-alternative, forced-choice task. Because differences between the acoustic stimuli are primarily constrained to their aTFS, successful discrimination reflects a combination of the subjects' perception of and the strategy's ability to deliver aTFS cues. Subjects were mapped with single-channel Continuous Interleaved Sampling (CIS) and Simultaneous Analog Stimulation (SAS) strategies. To compare within- and across- channel delivery of aTFS cues, a 16-channel clinical HiRes strategy was also fitted. Throughout testing, SAS consistently outperformed the CIS strategy (p ≤ 0.002). For SP stimuli with F0 = 50 Hz, the highest discrimination scores were achieved with the HiRes encoding, followed by scores with the SAS and the CIS strategies, respectively. At 200 Hz, single-channel SAS performed better than HiRes (p = 0.022), demonstrating that under a more challenging testing condition, discrimination performance with a single-channel analog encoding can exceed that of a 16-channel pulsatile strategy. To better understand the intermediate steps of discrimination, a biophysical model was used to examine the neural discharges evoked by the SP stimuli. Discrimination estimates calculated from simulated neural responses successfully tracked the behavioral performance trends of single-channel CI listeners.

Relationship between channel interaction and spectral-ripple discrimination in cochlear implant users.

Cochlear implant (CI) users can achieve remarkable speech understanding, but there is great variability in outcomes that is only partially accounted for by age, residual hearing, and duration of deafness. Results might be improved with the use of psychophysical tests to predict which sound processing strategies offer the best potential outcomes. In particular, the spectral-ripple discrimination test offers a time-efficient, nonlinguistic measure that is correlated with perception of both speech and music by CI users. Features that make this "one-point" test time-efficient, and thus potentially clinically useful, are also connected to controversy within the CI field about what the test measures. The current work examined the relationship between thresholds in the one-point spectral-ripple test, in which stimuli are presented acoustically, and interaction indices measured under the controlled conditions afforded by direct stimulation with a research processor. Results of these studies include the following: (1) within individual subjects there were large variations in the interaction index along the electrode array, (2) interaction indices generally decreased with increasing electrode separation, and (3) spectral-ripple discrimination improved with decreasing mean interaction index at electrode separations of one, three, and five electrodes. These results indicate that spectral-ripple discrimination thresholds can provide a useful metric of the spectral resolution of CI users.

Auditory training of speech recognition with interrupted and continuous noise maskers by children with hearing impairment.

Previous studies have indicated that individuals with normal hearing (NH) experience a perceptual advantage for speech recognition in interrupted noise compared to continuous noise. In contrast, adults with hearing impairment (HI) and younger children with NH receive a minimal benefit. The objective of this investigation was to assess whether auditory training in interrupted noise would improve speech recognition in noise for children with HI and perhaps enhance their utilization of glimpsing skills. A partially-repeated measures design was used to evaluate the effectiveness of seven 1-h sessions of auditory training in interrupted and continuous noise. Speech recognition scores in interrupted and continuous noise were obtained from pre-, post-, and 3 months post-training from 24 children with moderate-to-severe hearing loss. Children who participated in auditory training in interrupted noise demonstrated a significantly greater improvement in speech recognition compared to those who trained in continuous noise. Those who trained in interrupted noise demonstrated similar improvements in both noise conditions while those who trained in continuous noise only showed modest improvements in the interrupted noise condition. This study presents direct evidence that auditory training in interrupted noise can be beneficial in improving speech recognition in noise for children with HI.

Does enriched acoustic environment in humans abolish chronic tinnitus clinically and electrophysiologically? A double blind placebo controlled study.

Animal research has shown that loss of normal acoustic stimulation can increase spontaneous firing in the central auditory system and induce cortical map plasticity. Enriched acoustic environment after noise trauma prevents map plasticity and abolishes neural signs of tinnitus. In humans, the tinnitus spectrum overlaps with the area of hearing loss. Based on these findings it can be hypothesized that stimulating the auditory system by presenting music compensating specifically for the hearing loss might also suppress chronic tinnitus. To verify this hypothesis, a study was conducted in three groups of tinnitus patients. One group listened just to unmodified music (i.e. active control group), one group listened to music spectrally tailored to compensate for their hearing loss, and a third group received music tailored to overcompensate for their hearing loss, associated with one (in presbycusis) or two notches (in audiometric dip) at the edge of hearing loss. Our data indicate that applying overcompensation to the hearing loss worsens the patients' tinnitus loudness, the tinnitus annoyance and their depressive feelings. No significant effects were obtained for the control group or for the compensation group. These clinical findings were associated with an increase in current density within the left dorsal anterior cingulate cortex in the alpha2 frequency band and within the left pregenual anterior cingulate cortex in beta1 and beta2 frequency band. In addition, a region of interest analysis also demonstrated an associated increase in gamma band activity in the auditory cortex after overcompensation in comparison to baseline measurements. This was, however, not the case for the control or the compensation groups. In conclusion, music therapy compensating for hearing loss is not beneficial in suppressing tinnitus, and overcompensating hearing loss actually worsens tinnitus, both clinically and electrophysiologically.

Prevalence & characteristics of severe and profound hearing loss in adults in a UK National Health Service clinic.

OBJECTIVE: To estimate the prevalence of severe and profound hearing loss in a clinical population and to report the audiological and hearing-aid characteristics for this group, as well as outcome measures from use of hearing aids. DESIGN: A retrospective observational study initially, followed by a postal Glasgow health status inventory (GHSI) to establish the patients functional outcomes. STUDY SAMPLE: A clinical database of 32 781 cases was interrogated from which 2199 cases of severe /profound hearing loss were identified. From these, an adult sample stratified in terms of age and gender of n = 302 was contacted. RESULTS: An estimated 6.7% of the local clinical population and 0.7% of the general population were found to have hearing > 70 dB averaged over 0.5, 1, and 2 kHz. Most patients were fitted with bilateral hearing aids, using a non-linear prescription, and as a group they reported a high level of social support. CONCLUSIONS: This study has estimated the prevalence of severe and profound hearing loss as 6.7% of the clinical population, and 0.7% of the general population. This is consistent with previous work, although it probably underestimates the prevalence. Further work is indicated to strengthen the estimate.

Speech recognition in noise using bilateral open-fit hearing aids: the limited benefit of directional microphones and noise reduction.

OBJECTIVE: To investigate speech recognition performance in noise with bilateral open-fit hearing aids and as reference also with closed earmolds, in omnidirectional mode, directional mode, and directional mode in conjunction with noise reduction. DESIGN: A within-subject design with repeated measures across conditions was used. Speech recognition thresholds in noise were obtained for the different conditions. STUDY SAMPLE: Twenty adults without prior experience with hearing aids. All had symmetric sensorineural mild hearing loss in the lower frequencies and moderate to severe hearing loss in the higher frequencies. RESULTS: Speech recognition performance in noise was not significantly better with an omnidirectional microphone compared to unaided, whereas performance was significantly better with a directional microphone (1.6 dB with open fitting and 4.4 dB with closed earmold) compared to unaided. With open fitting, no significant additional advantage was obtained by combining the directional microphone with a noise reduction algorithm, but with closed earmolds a significant additional advantage of 0.8 dB was obtained. CONCLUSIONS: The significant, though limited, advantage of directional microphones and the absence of additional significant improvement by a noise reduction algorithm should be considered when fitting open-fit hearing aids.

Comodulation masking release induced by controlled electrical stimulation of auditory nerve fibers.

Normal-hearing listeners can perceptually segregate concurrent sound sources, but listeners with significant hearing loss or who wear a cochlear implant (CI) lag behind in this ability. Perceptual grouping mechanisms are essential to segregate concurrent sound sources and affect comodulation masking release (CMR). Thus, CMR measurements in CI users could shed light on segregation cues needed for forming and grouping of auditory objects. CMR illustrates the fact that detection of a target sound embedded in a fluctuating masker is improved by the addition of masker energy remote from the target frequency, provided the envelope fluctuations across masker components are coherent. We modified such a CMR experiment to electrically-induced hearing using direct stimulation and measured the effect in 21 CI users. Cluster analysis of our data revealed two groups: one showed no or only small CMR of 0.1 dB ± 2.7 (N = 14) and a second group achieved a CMR of 10.7 dB ± 3.2 (N = 7), a value that is close to the enhancement observed in a comparable acoustic experiment in normal-hearing listeners (12.9 dB ± 2.6, N = 6). Interestingly, we observed that CMR in CI users may relate to hearing etiology and duration of hearing loss pre-implantation. Our study demonstrates for the first time that a substantial minority of cochlear-implant listeners (about a third) can show significant CMR. This outcome motivates the development of physiologically inspired multi-band gain control and/or different coding strategies for these groups in order to better preserve coherent modulation and thus to take advantage of the individual remaining capabilities to analyze spectro-temporal patterns.

Stream segregation on a single electrode as a function of pulse rate in cochlear implant listeners.

While cochlear implants (CIs) usually provide high levels of speech recognition in quiet, speech recognition in noise remains challenging. To overcome these difficulties, it is important to understand how implanted listeners separate a target signal from interferers. Stream segregation has been studied extensively in both normal and electric hearing, as a function of place of stimulation. However, the effects of pulse rate, independent of place, on the perceptual grouping of sequential sounds in electric hearing have not yet been investigated. A rhythm detection task was used to measure stream segregation. The results of this study suggest that while CI listeners can segregate streams based on differences in pulse rate alone, the amount of stream segregation observed decreases as the base pulse rate increases. Further investigation of the perceptual dimensions encoded by the pulse rate and the effect of sequential presentation of different stimulation rates on perception could be beneficial for the future development of speech processing strategies for CIs.