The Association Between the Processing of Binaural Temporal-Fine-Structure Information and Audiometric Threshold and Age: A Meta-Analysis

The ability to process binaural temporal fine structure (TFS) information, which influences the perception of speech in spatially distributed soundscapes, declines with increasing hearing loss and age. Because of the relatively small sample sizes used in previous studies, and the population-unrepresentative distribution of hearing loss and ages within study samples, it has been difficult to determine the relative and combined contributions of hearing loss and age. The aim of this study was to survey published and unpublished studies that assessed binaural TFS sensitivity using the TFS-low frequency (LF) test. Results from 19 studies were collated, yielding sample sizes of 147 to 648, depending on the test frequency. At least for the test frequency of 500 Hz, there were at least 67 listeners in each of four adult age groups and the distribution of audiometric thresholds at the test frequency within each group was similar to that for the population as a whole. Binaural TFS sensitivity declined with increasing age across the adult lifespan and with increasing hearing loss in old adulthood. For all test frequencies, both audiometric threshold and age were significantly negatively correlated with TFS-LF sensitivity (r ranging from −0.19 to −0.64) but the correlation was always significantly higher for age than for audiometric threshold. Regression analyses showed that the standardized regression coefficient was greater for age than for audiometric threshold, and that there was a significant interaction; the effect of increasing age among older listeners was greater when the hearing loss was ≥30 dB than when it was < 30 dB.

Effects of Age and Hearing Loss on the Discrimination of Amplitude and Frequency Modulation for 2- and 10-Hz Rates

Detection of frequency modulation (FM) with rate = 10 Hz may depend on conversion of FM to amplitude modulation (AM) in the cochlea, while detection of 2-Hz FM may depend on the use of temporal fine structure (TFS) information. TFS processing may worsen with greater age and hearing loss while AM processing probably does not. A two-stage experiment was conducted to test these ideas while controlling for the effects of detection efficiency. Stage 1 measured psychometric functions for the detection of AM alone and FM alone imposed on a 1-kHz carrier, using 2- and 10-Hz rates. Stage 2 assessed the discrimination of AM from FM at the same modulation rate when the detectability of the AM alone and FM alone was equated. Discrimination was better for the 2-Hz than for the 10-Hz rate for all young normal-hearing subjects and for some older subjects with normal hearing at 1 kHz. Other older subjects with normal hearing showed no clear difference in AM-FM discrimination for the 2- and 10-Hz rates, as was the case for most older hearing-impaired subjects. The results suggest that the ability to use TFS cues is reduced for some older people and most hearing-impaired people.

Effectiveness of Audiologist-Delivered Cognitive Behavioral Therapy for Tinnitus and Hyperacusis Rehabilitation: Outcomes for Patients Treated in Routine Practice

OBJECTIVE

The aim was to assess the effectiveness of cognitive behavioral therapy (CBT) for tinnitus and/or hyperacusis delivered by audiologists working in the National Health Service in the United Kingdom.

DESIGN

This was a retrospective study, based on questionnaires assessing tinnitus and hyperacusis and insomnia before and after CBT.

STUDY SAMPLE

Data were gathered for 68 consecutive patients (average age = 52.5 years) who enrolled for CBT.

RESULTS

All measures showed significant improvements after CBT. Effect sizes for patients who completed CBT were 1.13 for Tinnitus Handicap Inventory scores; 0.76 for Hyperacusis Questionnaire scores; 0.71, 0.95, and 0.93 for tinnitus loudness, annoyance, and effect on life, respectively, measured using the Visual Analog Scale; and 0.94 for the Insomnia Severity Index score. An analysis including those who dropped out also showed significant improvements for all measures.

CONCLUSION

Audiologist-delivered CBT led to significant improvements in self-report measures of tinnitus and hyperacusis handicap and insomnia. The methods described here may be used when designing future randomized controlled trials of efficacy.

Sensorineural hearing loss impairs sensitivity but spares temporal integration for detection of frequency modulation

The effect of the number of modulation cycles (N) on frequency-modulation (FM) detection thresholds (FMDTs) was measured with and without interfering amplitude modulation (AM) for hearing-impaired (HI) listeners, using a 500-Hz sinusoidal carrier and FM rates of 2 and 20 Hz. The data were compared with FMDTs for normal-hearing (NH) listeners and AM detection thresholds (AMDTs) for NH and HI listeners [Wallaert, Moore, and Lorenzi (2016). J. Acoust. Soc. 139, 3088-3096; Wallaert, Moore, Ewert, and Lorenzi (2017). J. Acoust. Soc. 141, 971-980]. FMDTs were higher for HI than for NH listeners, but the effect of increasing N was similar across groups. In contrast, AMDTs were lower and the effect of increasing N was greater for HI listeners than for NH listeners. A model of temporal-envelope processing based on a modulation filter-bank and a template-matching decision strategy accounted better for the FMDTs at 20 Hz than at 2 Hz for young NH listeners and predicted greater temporal integration of FM than observed for all groups. These results suggest that different mechanisms underlie AM and FM detection at low rates and that hearing loss impairs FM-detection mechanisms, but preserves the memory and decision processes responsible for temporal integration of FM.

A Hearing-Model-Based Active-Learning Test for the Determination of Dead Regions

This article describes a Bayesian active-learning procedure for estimating the edge frequency, f_e, of a dead region, that is, a region in the cochlea with no or very few functioning inner hair cells or neurons. The method is based on the psychophysical tuning curve (PTC) but estimates the shape of the PTC from the parameters of a hearing model, namely f_e, and degree of outer hair cell loss. It chooses the masker frequency and level for each trial to be highly informative about the model parameters in the context of previous data. The procedure was tested using 14 ears from eight subjects previously diagnosed with high-frequency dead regions. The estimates of f_e agreed well with estimates obtained using “Fast PTCs” or more extensive measurements from an earlier study. On average, 33 trials were needed for the estimate of f_e to fall and stay within 0.3 Cams of the final “true” value on the equivalent rectangular bandwidth-number scale. The time needed to obtain a reliable estimate was 5 to 8 min. This is comparable to the time required for Fast PTCs and short enough to be used when fitting a hearing aid. Compared with Fast PTCs, the new method has the advantage of using yes-no judgments rather than continuous Békésy tracking. This allows the slope of a subject’s psychometric function and thus the reliability of his or her responses to be estimated, which in turn allows the test duration to be adjusted so as to achieve a given accuracy.

Audiogram estimation using Bayesian active learning

Two methods for estimating audiograms quickly and accurately using Bayesian active learning were developed and evaluated. Both methods provided an estimate of threshold as a continuous function of frequency. For one method, six successive tones with decreasing levels were presented on each trial and the task was to count the number of tones heard. A Gaussian Process was used for classification and maximum-information sampling to determine the frequency and levels of the stimuli for the next trial. The other method was based on a published method using a Yes/No task but extended to account for lapses. The obtained audiograms were compared to conventional audiograms for 40 ears, 19 of which were hearing impaired. The threshold estimates for the active-learning methods were systematically from 2 to 4 dB below (better than) those for the conventional audiograms, which may indicate a less conservative response criterion (a greater willingness to respond for a given amount of sensory information). Both active-learning methods were able to allow for wrong button presses (due to lapses of attention) and provided accurate audiogram estimates in less than 50 trials or 4 min. For a given level of accuracy, the counting task was slightly quicker than the Yes/No task.

Effect of harmonic rank on sequential sound segregation

The ability to segregate sounds from different sound sources is thought to depend on the perceptual salience of differences between the sounds, such as differences in frequency or fundamental frequency (F0). F0 discrimination of complex tones is better for tones with low harmonics than for tones that only contain high harmonics, suggesting greater pitch salience for the former. This leads to the expectation that the sequential stream segregation (streaming) of complex tones should be better for tones with low harmonics than for tones with only high harmonics. However, the results of previous studies are conflicting about whether this is the case. The goals of this study were to determine the effect of harmonic rank on streaming and to establish whether streaming is related to F0 discrimination. Thirteen young normal-hearing participants were tested. Streaming was assessed for pure tones and complex tones containing harmonics with various ranks using sequences of ABA triplets, where A and B differed in frequency or in F0. The participants were asked to try to hear two streams and to indicate when they heard one and when they heard two streams. F0 discrimination was measured for the same tones that were used as A tones in the streaming experiment. Both streaming and F0 discrimination worsened significantly with increasing harmonic rank. There was a significant relationship between streaming and F0 discrimination, indicating that good F0 discrimination is associated with good streaming. This supports the idea that the extent of stream segregation depends on the salience of the perceptual difference between successive sounds.

Evaluation of a multi-channel algorithm for reducing transient sounds

OBJECTIVE

The objective was to evaluate and select appropriate parameters for a multi-channel transient reduction (MCTR) algorithm for detecting and attenuating transient sounds in speech.

DESIGN

In each trial, the same sentence was played twice. A transient sound was presented in both sentences, but its level varied across the two depending on whether or not it had been processed by the MCTR and on the "strength" of the processing. The participant indicated their preference for which one was better and by how much in terms of the balance between the annoyance produced by the transient and the audibility of the transient (they were told that the transient should still be audible).

STUDY SAMPLE

Twenty English-speaking participants were tested, 10 with normal hearing and 10 with mild-to-moderate hearing-impairment. Frequency-dependent linear amplification was provided for the latter.

RESULTS

The results for both participant groups indicated that sounds processed using the MCTR were preferred over the unprocessed sounds. For the hearing-impaired participants, the medium and strong settings of the MCTR were preferred over the weak setting.

CONCLUSIONS

The medium and strong settings of the MCTR reduced the annoyance produced by the transients while maintaining their audibility.

Use of a Deep Recurrent Neural Network to Reduce Wind Noise: Effects on Judged Speech Intelligibility and Sound Quality

Despite great advances in hearing-aid technology, users still experience problems with noise in windy environments. The potential benefits of using a deep recurrent neural network (RNN) for reducing wind noise were assessed. The RNN was trained using recordings of the output of the two microphones of a behind-the-ear hearing aid in response to male and female speech at various azimuths in the presence of noise produced by wind from various azimuths with a velocity of 3 m/s, using the “clean” speech as a reference. A paired-comparison procedure was used to compare all possible combinations of three conditions for subjective intelligibility and for sound quality or comfort. The conditions were unprocessed noisy speech, noisy speech processed using the RNN, and noisy speech that was high-pass filtered (which also reduced wind noise). Eighteen native English-speaking participants were tested, nine with normal hearing and nine with mild-to-moderate hearing impairment. Frequency-dependent linear amplification was provided for the latter. Processing using the RNN was significantly preferred over no processing by both subject groups for both subjective intelligibility and sound quality, although the magnitude of the preferences was small. High-pass filtering (HPF) was not significantly preferred over no processing. Although RNN was significantly preferred over HPF only for sound quality for the hearing-impaired participants, for the results as a whole, there was a preference for RNN over HPF. Overall, the results suggest that reduction of wind noise using an RNN is possible and might have beneficial effects when used in hearing aids.

No evidence for enhanced processing of speech that is low-pass filtered near the edge frequency of cochlear dead regions in children

OBJECTIVES

Cochlear dead regions (DRs) are regions in the cochlea where the inner hair cells and/or neurons are not functioning. Adults with extensive high-frequency DRs have enhanced abilities in processing sounds with frequencies just below the edge frequency, f_edge, of the DR. It was assessed whether the same is true for children.

DESIGN

Performance was compared for children aged 8 to 13 years with: DRs (group DR), hearing impairment but without DRs (group NODR), and normal hearing (group NH). Seven ears in each group were tested. Each ear in the DR group was matched in age and low-frequency hearing with an ear in the NODR group, and in age with an ear in the NH group, giving seven "triplets". Within each triplet, the percent correct identification of vowel-consonant-vowel stimuli was measured using stimuli that were low-pass filtered at f_edge and 0.67f_edge, based on the ear with a DR. For the hearing-impaired ears, stimuli were given frequency-selective amplification as prescribed by DSL 4.1.

RESULTS

No significant differences in performance were found between groups for either low-pass cut-off frequency.

CONCLUSION

Unlike adults, the children with DRs did not show enhanced discrimination of speech stimuli with frequencies below f_edge.

A Loudness Model for Time-Varying Sounds Incorporating Binaural Inhibition

This article describes a model of loudness for time-varying sounds that incorporates the concept of binaural inhibition, namely, that the signal applied to one ear can reduce the internal response to a signal at the other ear. For each ear, the model includes the following: a filter to allow for the effects of transfer of sound through the outer and middle ear; a short-term spectral analysis with greater frequency resolution at low than at high frequencies; calculation of an excitation pattern, representing the magnitudes of the outputs of the auditory filters as a function of center frequency; application of a compressive nonlinearity to the output of each auditory filter; and smoothing over time of the resulting instantaneous specific loudness pattern using an averaging process resembling an automatic gain control. The resulting short-term specific loudness patterns are used to calculate broadly tuned binaural inhibition functions, the amount of inhibition depending on the relative short-term specific loudness at the two ears. The inhibited specific loudness patterns are summed across frequency to give an estimate of the short-term loudness for each ear. The overall short-term loudness is calculated as the sum of the short-term loudness values for the two ears. The long-term loudness for each ear is calculated by smoothing the short-term loudness for that ear, again by a process resembling automatic gain control, and the overall loudness impression is obtained by summing the long-term loudness across ears. The predictions of the model are more accurate than those of an earlier model that did not incorporate binaural inhibition.

Testing and refining a loudness model for time-varying sounds incorporating binaural inhibition

This paper describes some experimental tests and modifications to a model of loudness for time-varying sounds incorporating the concept of binaural inhibition. Experiment 1 examined the loudness of a 100% sinusoidally amplitude-modulated 1000-Hz sinusoidal carrier as a function of the interaural modulation phase difference (IMPD). The IMPD of the test sound was 90° or 180° and that of the comparison sound was 0°. The level difference between the test and the comparison sounds at the point of equal loudness (the LDEL) was estimated for baseline levels of 30 and 70 dB sound pressure level and modulation rates of 1, 2, 4, 8, 16, and 32 Hz. The LDELs were negative (mean = -1.1 and -1.5 dB for IMPDs of 90° and 180°), indicating that non-zero IMPDs led to increased loudness. The original version of the model predicted the general form of the results, but there were some systematic errors. Modifications to the time constants of the model gave a better fit to the data. Experiment 2 assessed the loudness of unintelligible speech-like signals, generated using a noise vocoder, whose spectra and time pattern differed at the two ears. Both the original and modified models gave good fits to the data.

Effects of age on sensitivity to interaural time differences in envelope and fine structure, individually and in combination

Sensitivity to interaural time differences (ITDs) in envelope and temporal fine structure (TFS) of amplitude-modulated (AM) tones was assessed for young and older subjects, all with clinically normal hearing at the carrier frequencies of 250 and 500 Hz. Some subjects had hearing loss at higher frequencies. In experiment 1, thresholds for detecting changes in ITD were measured when the ITD was present in the TFS alone (ITD_TFS), the envelope alone (ITD_ENV), or both (ITD_TFS/ENV). Thresholds tended to be higher for the older than for the young subjects. ITD_ENV thresholds were much higher than ITD_TFS thresholds, while ITD_TFS/ENV thresholds were similar to ITD_TFS thresholds. ITD_TFS thresholds were lower than ITD thresholds obtained with an unmodulated pure tone, indicating that uninformative AM can improve ITD_TFS discrimination. In experiment 2, equally detectable values of ITD_TFS and ITD_ENV were combined so as to give consistent or inconsistent lateralization. There were large individual differences, but several subjects gave scores that were much higher than would be expected from the optimal combination of independent sources of information, even for the inconsistent condition. It is suggested that ITD_TFS and ITD_ENV cues are processed partly independently, but that both cues influence lateralization judgments, even when one cue is uninformative.

The effect of F0 contour on the intelligibility of speech in the presence of interfering sounds for Mandarin Chinese

In Mandarin Chinese, the fundamental frequency (F0) contour defines lexical "Tones" that differ in meaning despite being phonetically identical. Flattening the F0 contour impairs the intelligibility of Mandarin Chinese in background sounds. This might occur because the flattening introduces misleading lexical information. To avoid this effect, two types of speech were used: single-Tone speech contained Tones 1 and 0 only, which have a flat F0 contour; multi-Tone speech contained all Tones and had a varying F0 contour. The intelligibility of speech in steady noise was slightly better for single-Tone speech than for multi-Tone speech. The intelligibility of speech in a two-talker masker, with the difference in mean F0 between the target and masker matched across conditions, was worse for the multi-Tone target in the multi-Tone masker than for any other combination of target and masker, probably because informational masking was maximal for this combination. The introduction of a perceived spatial separation between the target and masker, via the precedence effect, led to better performance for all target-masker combinations, especially the multi-Tone target in the multi-Tone masker. In summary, a flat F0 contour does not reduce the intelligibility of Mandarin Chinese when the introduction of misleading lexical cues is avoided.

Individually tailored spectral-change enhancement for the hearing impaired

An algorithm for enhancing spectral changes over time was previously shown to improve the intelligibility of speech in steady speech-spectrum noise (SSN) for hearing-impaired subjects but tended to impair intelligibility for speech in a background of two-talker speech. Large individual differences were found and the application of a genetic algorithm for selecting the "best" parameter values for each listener was found to be beneficial. In the present study, the spectral-change enhancement (SCE) processing was modified by individually tailoring the degree of SCE based on the frequency-dependent hearing loss of the subjects, and by using finer frequency resolution. The effect of the modified SCE processing on the intelligibility and quality of speech in SSN and babble noise (BBN) was evaluated. Ten subjects with mild to moderate hearing loss were tested twice for all tests. The SCE processing led to small but significant improvements in the intelligibility of speech in both SSN and BBN, while the effect of the SCE processing on speech quality was small.

Senescent Changes in Sensitivity to Binaural Temporal Fine Structure

Differences in the temporal fine structure (TFS) of sounds at the two ears are used for sound localization and for the perceptual analysis of complex auditory scenes. The ability to process this binaural TFS information is poorer for older than for younger participants, and this may contribute to age-related declines in the ability to understand speech in noisy situations. However, it is unclear how sensitivity to binaural TFS changes across the older age range. This article presents data for a test of binaural sensitivity to TFS, the "TFS-adaptive frequency" (AF) test, for 118 listeners aged 60 to 96 years with normal or near-normal low-frequency hearing, but a variety of patterns of hearing loss at higher frequencies. TFS-AF scores were significantly lower (i.e., poorer) than those for young adults. On average, scores decreased by about 162 Hz for each 10-year increase in age over the range 60 to 85 years. Individual variability increased with increasing age. Scores also declined as low-frequency audiometric thresholds worsened. The results illustrate the range of scores that can be obtained as a function of age and may be useful for the diagnosis and management of age-related hearing difficulties.

Factors Associated With Depression in Patients With Tinnitus and Hyperacusis

PURPOSE

The purpose of this study was to assess factors associated with depression for patients with tinnitus and hyperacusis.

METHOD

Data were gathered from the records of 620 consecutive patients who sought help concerning their tinnitus or hyperacusis from an audiology clinic in the United Kingdom.

RESULTS

One third of the patients had borderline abnormal or abnormal scores on the Depression subscale of the Hospital Anxiety and Depression Scale (HADS-D). Linear regression models showed that HADS-D scores were related to scores for tinnitus handicap, tinnitus loudness, and uncomfortable loudness levels. Mediation analyses showed that (a) the influence of tinnitus handicap scores on HADS-D scores was mainly mediated via the effects of insomnia, hyperacusis, and anxiety; (b) the influence of tinnitus loudness scores on HADS-D scores was fully mediated via the effects of tinnitus handicap, insomnia, hyperacusis handicap, and anxiety; (c) and the small influence of uncomfortable loudness levels on HADS-D scores was fully mediated by hyperacusis handicap and anxiety.

CONCLUSION

Those involved in the management of patients with tinnitus and/or hyperacusis should use a wide range of instruments to assess the full impact of tinnitus on a patient's life and should be prepared to refer a patient for treatment for depression, especially when the patient has anxiety, hyperacusis, and/or insomnia.

The detailed shapes of equal-loudness-level contours at low frequencies

High-resolution equal-loudness-level contours (ELCs) were measured over the frequency range 10-250 Hz using 19 normal-hearing subjects. Three levels of the 50-Hz reference sound were used, corresponding to the levels at 50 Hz of the 30-, 50-, and 70-phon standardized ELCs given in ISO-226:2003. The dynamic range of the contours generally decreased with increasing reference level, and the slope was shallow between 10 and 20 Hz, consistent with previous studies. For the lowest level, the ELCs were sometimes but not always smooth and on average followed the standardized 30-phon contour for frequencies above 40 Hz. For the two higher levels, the individual ELCs showed a distinct non-monotonic feature in a "transition region" between about 40 and 100 Hz, where the slope could reach near-zero or even positive values. The pattern of the non-monotonic feature was similar across levels for the subjects for whom it was observed, but the pattern varied across subjects. Below 40 Hz, the slopes of the ELCs increased markedly for all loudness levels, and the levels exceeded those of the standardized ELCs. Systematic deviations from the standardized ELCs were largest for frequencies below 40 Hz for all levels and within the transition region for the two higher levels.

Incidence of Discomfort During Pure-Tone Audiometry and Measurement of Uncomfortable Loudness Levels Among People Seeking Help for Tinnitus and/or Hyperacusis

PURPOSE

The aim of this study was to assess the proportion of patients seen in a tinnitus and hyperacusis therapy clinic for whom presentation levels based on the British Society of Audiology (BSA)-recommended procedures for pure-tone audiometry and determination of uncomfortable loudness levels (ULLs) exceed ULLs, leading to discomfort during administration of these procedures.

METHOD

This was a retrospective cross-sectional study of 362 consecutive patients who attended a National Health Service audiology clinic for tinnitus and/or hyperacusis rehabilitation.

RESULTS

For 21% of the patients, presentation levels based on the BSA procedure for pure-tone audiometry exceeded the ULL for at least 1 of the measured frequencies (excluding the first frequency tested, 1 kHz): 0.25, 0.5, 2, 3, 4, 6, and 8 kHz. For 24% of patients, the starting presentation level of 60 dB hearing level recommended for determination of ULLs exceeded the ULL for at least 1 frequency.

CONCLUSION

The starting presentation levels used for pure-tone audiometry and measurement of ULLs should be lower than those recommended by the BSA for people with tinnitus and hyperacusis.