Informational masking in young and elderly listeners for speech masked by simultaneous speech and noise.

Three experiments measured the effects of age on informational masking of speech by competing speech. The experiments were designed to minimize the energetic contributions of the competing speech so that informational masking could be measured with no large corrections for energetic masking. Experiment 1 used a "speech-in-speech-in-noise" design, in which the competing speech was presented in noise at a signal-to-noise ratio (SNR) of -4 dB. This ensured that the noise primarily contributed the energetic masking but the competing speech contributed the informational masking. Equal amounts of informational masking (3 dB) were observed for young and elderly listeners, although less was found for hearing-impaired listeners. Experiment 2 tested a range of SNRs in this design and showed that informational masking increased with SNR up to about an SNR of -4 dB, but decreased thereafter. Experiment 3 further reduced the energetic contribution of the competing speech by filtering it into different frequency bands from the target speech. The elderly listeners again showed approximately the same amount of informational masking (4-5 dB), although some elderly listeners had particular difficulty understanding these stimuli in any condition. On the whole, these results suggest that young and elderly listeners were equally susceptible to informational masking.

The design of a project to assess bilateral versus unilateral hearing aid fitting.

Binaural hearing provides advantages over monaural in several ways, particularly in difficult listening situations. For a person with bilateral hearing loss, the bilateral fitting of hearing aids thus seems like a natural choice. However, surprisingly few studies have been reported in which the additional benefit of bilateral versus unilateral hearing aid use has been investigated based on real-life experiences. Therefore, a project has been designed to address this issue and to find tools to identify people for whom the drawbacks would outweigh the advantages of bilateral fitting. A project following this design is likely to provide reliable evidence concerning differences in benefit between unilateral and bilateral fitting of hearing aids by evaluating correlations between entrance data and outcome measures and final preferences.

The effects of cueing temporal and spatial attention on word recognition in a complex listening task in hearing-impaired listeners.

In a complex listening situation such as a multiperson conversation, the demands on an individual's attention are considerable: There will often be many sounds occurring simultaneously, with continual changes in source and direction. A laboratory analog of this was designed to measure the benefit that helping attention (by visual cueing) would have on word identification. These words were presented unpredictably but were sometimes cued with a temporal cue or a temporal-and-spatial cue. Two groups of hearing-impaired, older-adult listeners participated, 57 unaided and 19 aided. There was a small effect of cueing: The cues gave a 2% benefit in word identification. A variety of subsidiary measures were collected, including the Test of Everyday Attention and the Speech, Spatial, & Qualities of Hearing Questionnaire, but their links with the benefits of cueing were few. The results demonstrate the difficulty of cueing attention to improve word recognition in a complex listening situation.

Discrimination of release time constants in hearing-aid compressors.

We examined the ability of twenty-five hearing-impaired and eight normal-hearing listeners to discriminate between release time constants used for compression in hearing aids. The compressor was a standard three-channel system. The stimuli were normal and 'vocoded' sentences from a male and female database. In agreement with other studies looking at different outcomes, performance varied greatly across individuals. This variation was greater in hearing-impaired listeners, for whom the discriminability of a release time of 5 ms from one of 5000 ms (with the attack time fixed at 5 ms) ranged from chance to perfect. This variability was not significantly related to hearing impairment nor to individuals' compression ratios.

Spatial hearing disability after acoustic neuroma removal.

OBJECTIVES/HYPOTHESIS: Previous studies on hearing loss (HL) after acoustic neuroma removal concentrate mainly on pure-tone hearing results rather than hearing disability. Our objectives were to use the Speech, Spatial and Qualities of Hearing scale (SSQ), a comprehensively validated questionnaire, to characterize and quantify the auditory disabilities that patients experience with a profound unilateral HL after acoustic neuroma removal. STUDY DESIGN: Forty-four patients with profound unilateral HL after acoustic neuroma surgery completed the SSQ. Their findings were compared with those of a control population sample matched for age, sex, and hearing level in the better hearing ear. RESULTS: In comparison with controls, with use of analysis of variance, acoustic neuroma patients scored poorly on all items except for the identification of sounds and objects (P = .123). The greatest difficulties involved speech in the presence of noise, situations of multiple speech-streams and switching (such as listening to someone speaking and the television at the same time), the location of unseen objects, and increased listening effort (P < .05). CONCLUSION: This study demonstrates that, compared with a control population, these patients experience a significant range of auditory disabilities. It is important that clinicians be aware of the impact of such a profound unilateral HL and its potential to affect daily life. Patient counseling prior to surgery is essential, especially in patients whose loss of binaural hearing could constitute a major disability.

The binaural performance of a cross-talk cancellation system with matched or mismatched setup and playback acoustics.

Cross-talk cancellation is a method for synthesizing virtual auditory space using loudspeakers. One implementation is the "Optimal Source Distribution" technique [T. Takeuchi and P. Nelson, J. Acoust. Soc. Am. 112, 2786-2797 (2002)], in which the audio bandwidth is split across three pairs of loudspeakers, placed at azimuths of +/-90 degrees, +/-15 degrees, and +/-3 degrees, conveying low, mid, and high frequencies, respectively. A computational simulation of this system was developed and verified against measurements made on an acoustic system using a manikin. Both the acoustic system and the simulation gave a wideband average cancellation of almost 25 dB. The simulation showed that when there was a mismatch between the head-related transfer functions used to set up the system and those of the final listener, the cancellation was reduced to an average of 13 dB. Moreover, in this case the binaural interaural time differences and interaural level differences delivered by the simulation of the optimal source distribution (OSD) system often differed from the target values. It is concluded that only when the OSD system is set up with "matched" head-related transfer functions can it deliver accurate binaural cues.

The detection of differences in the cues to distance by elderly hearing-impaired listeners.

This experiment measured the capability of hearing-impaired individuals to discriminate differences in the cues to the distance of spoken sentences. The stimuli were generated synthetically, using a room-image procedure to calculate the direct sound and first 74 reflections for a source placed in a 7 x 9 m room, and then presenting each of those sounds individually through a circular array of 24 loudspeakers. Seventy-seven listeners participated, aged 22-83 years and with hearing levels from -5 to 59 dB HL. In conditions where a substantial change in overall level due to the inverse-square law was available as a cue, the elderly hearing-impaired listeners did not perform any different from control groups. In other conditions where that cue was unavailable (so leaving the direct-to-reverberant relationship as a cue), either because the reverberant field dominated the direct sound or because the overall level had been artificially equalized, hearing-impaired listeners performed worse than controls. There were significant correlations with listeners' self-reported distance capabilities as measured by the "Speech, Spatial, and Qualities of Hearing" questionnaire [S. Gatehouse and W. Noble, Int. J. Audiol. 43, 85-99 (2004)]. The results demonstrate that hearing-impaired listeners show deficits in the ability to use some of the cues which signal auditory distance.

Two-eared listening in dynamic situations.

Reports of hearing disabilities, particularly those acoustically and perceptually dynamic circumstances, are associated with compromised binaural capacities. Those disabilities that are compromised largely correspond to the areas where benefits of bilateral fitting over unilateral fitting emerge. The singular exception is for disabilities in "Sound quality and naturalness". When binaural capacities are measured by traditional static masking level difference paradigms, relationships between compromised binaural capacity and self-reports of disability are largely absent. However, when masking level differences are assessed using dynamic parameters that are more representative of the conditions experienced in everyday living then significant associations between binaural capacities and self-reports of disability do emerge. We contend that, for both the self-report domain and the psychoacoustical domain, procedures should be more properly representative of the dynamic environments that listeners are routinely exposed to.

Linear and nonlinear hearing aid fittings--1. Patterns of benefit.

We evaluated the benefits of fast-acting WDRC, slow-acting AVC, and linear reference fittings for speech intelligibility and reported disability, in a within-subject within-device masked crossover design on 50 listeners with SNHL. Five hearing aid fittings were implemented having two compression channels and seven frequency bands. Each listener sequentially experienced each fitting for a 10-week period. Outcome measures included speech intelligibility under diverse conditions and self-reported disability. At a group level, each nonlinear fitting was superior to the linear references for benefits in listening comfort, listener satisfaction, reported intelligibility and speech intelligibility. Slow-acting AVC outperformed the fast-acting WDRC fittings for listening comfort, while for reported and measured speech intelligibility the converse was true. For listener satisfaction there were no group differences between the nonlinear fittings. Analysis in terms of fittings for individual listeners revealed subsets with definite divergences from the group data and hence a need for candidature criteria. There are systematic differences between the benefits of nonlinear and linear fittings, and also within nonlinear fittings with fast versus slow time constants. The patterns of benefit and individual optima depend on the domain of outcome being assessed.

Linear and nonlinear hearing aid fittings--2. Patterns of candidature.

We studied candidature for linear, slow-acting AVC hearing aids, and fast-acting WDRC hearing aids in a within-subject within-device crossover design of 50 listeners with SNHL. Candidature dimensions include HTLs, ULLs, spectro-temporal and masking abnormalities, cognitive capacity, and self-reports and acoustic measures of auditory ecology. Better performance with linear fittings is associated with flatter audiograms, wider dynamic range, and smaller differences in dynamic range between low and high frequencies, and also with more restricted auditory lifestyles. Better performance with all nonlinear fittings is associated with more sloping audiograms, more restricted dynamic ranges, greater differences in dynamic range between low and high frequencies, and more varied auditory lifestyles. Differential performance between WDRC and AVC fittings is associated with patterns of variation in auditory ecology (rapid versus slow changes) and cognitive (high versus low) capacity. Differential performance between WDRC in two channels, and a hybrid with WDRC in a low-frequency and AVC in a high-frequency channel is associated with psychoacoustic tests of cochlear function (high susceptibility to spectral and temporal smearing, and high susceptibility to upward spread of masking respectively). Patterns of candidature include measures beyond auditory function in the domains of cognitive capacity and auditory ecology.

Effects of bilateral versus unilateral hearing aid fitting on abilities measured by the Speech, Spatial, and Qualities of Hearing Scale (SSQ).

The Speech, Spatial and Qualities of Hearing Scale (Gatehouse & Noble, 2004) was applied to three independent clinical groups: 144 people prior to being fitted with amplification; 118 people with six months experience with unilateral amplification; and 42 people with six months experience with bilateral amplification. For traditional speech hearing contexts (one-on-one, in groups, in quiet, in noise) there was benefit with one aid, and no further benefit with two. By contrast, hearing speech in demanding contexts (divided or rapidly switching attention) showed benefit with one aid and further benefit with two. In the spatial domain, directional hearing showed some benefit with one hearing aid, and particular further benefit in distance and movement discrimination from fitting with two. There was some benefit from unilateral fitting for elements of the qualities domains (clarity, naturalness, recognisability, segregation of sounds), with no consistent sign of further benefit from two. Bilateral fitting added benefit with respect to listening effort. Two hearing aids offer advantage in demanding and dynamic contexts; these contexts are argued as significant in the maintenance of social competence and emotional wellbeing. The present results go toward establishing the real-world advantages of bilateral hearing aid fitting and suggest that previous, inconclusive clinical findings reflect inquiry limited to more traditional areas of hearing function.

Does patient-perceived handicap correspond to the modified clinical test for the sensory interaction on balance?

OBJECTIVE: To determine whether patient self-reported handicap correlates with scores obtained from the modified Clinical Test for the Sensory Interaction on Balance as assessed by the Neurocom VSR Balance Master platform. STUDY DESIGN: Prospective observational. SETTING: Balance clinic in tertiary referral center. PATIENTS: Patients referred with dizziness or imbalance as their primary complaint. OUTCOME MEASURES: The modified Clinical Test for the Sensory Interaction on Balance scores as assessed by the Neurocom VSR Balance Master platform, the Dizziness Handicap Inventory, and the Health Utilities Index Marks 2 and 3. RESULTS: One hundred fifty-nine patients were entered into the study. The mean age of participants was 54.5 years, with a female-to-male ratio of 2.1:1. The scores for the Dizziness Handicap Inventory and Health Utilities Index are similar between sexes, and although the Dizziness Handicap Inventory score did not correlate with age, Health Utilities Index 2 and 3 scores did show a negative correlation with increasing age. There are weak, positive correlations between the Dizziness Handicap Inventory and the firm surface conditions of the modified Clinical Test for the Sensory Interaction on Balance but no useful correlation with the foam conditions. Similar weak negative correlations were found between the Health Utilities Index 2 and 3 and the modified Clinical Test for the Sensory Interaction on Balance scores. CONCLUSION: Patient-perceived handicap of imbalance appears to correlate poorly with assessment of postural stability using the modified Clinical Test for the Sensory Interaction on Balance.

Localization and speech-identification ability of hearing-impaired listeners using phase-preserving amplification.

OBJECTIVE: The purpose of these experiments was to determine the ability of hearing-impaired listeners to localize and to identify speech in noise using phase-preserving and non-phase-preserving amplification. DESIGN: These abilities were measured 4 times over each of two 16-week periods, using a randomized, single-blinded, within-subject crossover design. Listeners were fitted bilaterally, using the National Acoustic Laboratories linear frequency-gain characteristic with a digital hearing aid programmed in one of two ways: (1) with a linear-phase filter and (2) with filters designed to compensate for the magnitude and phase anomalies caused by the hearing aid fitting, thus preserving interaural phase. Listeners identified a word and its location in background noise with a speech-shaped spectrum. RESULTS: Immediately after fitting, both hearing aid programs reduced the listeners' ability to localize the speech in noise. The phase-preserving processing had a less detrimental effect on localization ability immediately after fitting. After 3 weeks, performance improved such that, for localization in noise, there was no detrimental effect of amplification and no difference between the two processing strategies. Over 16 weeks, speech understanding in noise improved. Speech understanding for phase-preserving processing was slightly and significantly better than linear-phase processing at 16 weeks. CONCLUSIONS: Localization ability using phase-preserving amplification does not differ from localization ability using traditional non-phase-preserving amplification after just 3 weeks of use. Listeners quickly acclimated to altered spatial cues. Phase-preserving amplification provided a 2.3% advantage for speech intelligibility in noise after 16 weeks.

Measuring quality of life in preschool children with sore throats and otitis media using the TAPQOL questionnaire.

OBJECTIVES: TNO-AZL Preschool Quality of Life Questionnaire (TAPQOL) is one of the few instruments designed to assess health-related quality of life in preschool children but its applicability to otolaryngology is unknown. STUDY DESIGN AND SETTING: We studied a consecutive series of children aged 1 to 5 years referred to hospital with recurrent sore throats, recurrent acute otitis media, or otitis media with effusion. RESULTS: TAPQOL domain scores were not influenced by age, sex, or socio-economic class, but correlated with markers of disease severity (frequency of sore throat or pyrexia, time off school), ear-related handicap (assessed with the OM6 questionnaire), and other measures of health-related quality of life (visual analogue scale, 5-point rating scale and the Health Utilities Index mark III). Comparison with published data from healthy children suggests that these common otolaryngologic problems have a large impact on a child's quality of life. CONCLUSIONS: TAPQOL seems to be appropriate for use in this context. Marked ceiling effects in some domains, however, may limit their sensitivity.

How appropriate is the OM6 as a discriminative instrument in children with otitis media?

BACKGROUND: The OM6 is a 6-item condition-specific handicap measure developed in the United States for children with recurrent acute otitis media and otitis media with effusion. Easy and quick to use, it has high test-retest repeatability and is sensitive to change after ventilation tube insertion. OBJECTIVES: To explore aspects of the validity of OM6 in a United Kingdom population and to specifically address the instrument's ability to discriminate between children with different burdens of disease. DESIGN: The parents of 179 consecutive newly referred children with otitis media with effusion or recurrent acute otitis media completed the OM6 on their first visit to the hospital. The parents of 72 children with sore throats completed the OM6 for comparison. Scores were compared with markers of disease severity, demographic variables, and generic quality-of-life measures. RESULTS: Poorer scores were found in those with ear complaints than in those with sore throats. The OM6 scores were not associated with age, sex, socioeconomic class, or respondent (mother vs father). The OM6 scores did not correlate with frequency of otalgia, frequency of otorrhea, or time off school in the recurrent acute otitis media group. In the otitis media with effusion group, poorer scores were associated with bilateral B or C2 tympanometric findings but not with a better ear threshold of more than 20 dB. Correlation with a global 10-cm visual analog scale for quality of life and with the Health Utilities Index Mark III was good. CONCLUSIONS: The OM6 scores correlate well with global quality-of-life measures and are free from many potential biases. However, OM6 does not adequately reflect disease severity, which may limit its usefulness as a discriminative measure.

The Speech, Spatial and Qualities of Hearing Scale (SSQ).

The Speech, Spatial and Qualities of Hearing Scale (SSQ) is designed to measure a range of hearing disabilities across several domains. Particular attention is given to hearing speech in a variety of competing contexts, and to the directional, distance and movement components of spatial hearing. In addition, the abilities both to segregate sounds and to attend to simultaneous speech streams are assessed, reflecting the reality of hearing in the everyday world. Qualities of hearing experience include ease of listening, and the naturalness, clarity and identifiability of different speakers, different musical pieces and instruments, and different everyday sounds. Application of the SSQ to 153 new clinic clients prior to hearing aid fitting showed that the greatest difficulty was experienced with simultaneous speech streams, ease of listening, listening in groups and in noise, and judging distance and movement. SSQ ratings were compared with an independent measure of handicap. After differences in hearing level were controlled for, it was found that identification, attention and effort problems, as well as spatial hearing problems, feature prominently in the disability handicap relationship,. along with certain features of speech hearing. The results implicate aspects of temporal and spatial dynamics of hearing disability in the experience of handicap. The SSQ shows promise as an instrument for evaluating interventions of various kinds, particularly (but not exclusively) those that implicate binaural function.

Interaural asymmetry of hearing loss, Speech, Spatial and Qualities of Hearing Scale (SSQ) disabilities, and handicap.

A series of comparative analyses is presented between a group with relatively similar degrees of hearing loss in each ear (n = 103: symmetry group) and one with dissimilar losses (n = 50: asymmetry group). Asymmetry was defined as an interaural difference of more than 10dB in hearing levels averaged over 0.5. 1, 2 and 4kHz. Comparison was focused on self-rated disabilities as reflected in responses on the Speech, Spatial and Qualities of Hearing Scale (SSQ). The connections between SSQ ratings and a global self-rating of handicap were also observed. The interrelationships among SSQ items for the two groups were analysed to determine how the SSQ behaves when applied to groups in whom binaural hearing is more (asymmetry) versus less compromised. As expected, spatial hearing is severely disabled in the group with asymmetry; this group is generally more disabled than the symmetry group across all SSQ domains. In the linkages with handicap, spatial hearing, especially in dynamic settings, was strongly represented in the asymmetry group, while all aspects of hearing were moderately to strongly represented in the symmetry group. Item intercorrelations showed that speech hearing is a relatively autonomous function for the symmetry group, whereas it is enmeshed with segregation, clarity and naturalness factors for the asymmetry group. Spatial functions were more independent of others in the asymmetry group. The SSQ shows promise in the assessment of outcomes in the case of bilateral versus unilateral amplification and/or implantation.

The Glasgow Children's Benefit Inventory: a new instrument for assessing health-related benefit after an intervention.

Most health-related quality-of-life measures make an assessment at a single point in time. Comparing results before and after an intervention is often difficult, because the difference measured is usually small compared with the variation between individuals. A retrospectively applied measure specifically worded to assess benefit would be very useful for clinical research. Such a measure exists for adults. We aimed to develop a similar measure for children. We chose potential items after reviewing existing health-related quality-of-life measures, published literature, and parental interviews. A draft questionnaire was given to a group of parents and modified. The resulting Glasgow Children's Benefit Inventory (GCBI) comprised 24 questions on the consequences of a specified intervention on various aspects of the child's day-to-day life, without reference to any specific symptoms, and was worded to apply to children of any age. The questionnaire was mailed to the parents of all 1,777 children who had undergone tonsillectomy or ventilation tube insertion at one hospital during the period January 1998 to December 2001. There were 670 questionnaires returned. The GCBI scores correlated well with parental satisfaction with surgery and with estimates of technical success (residual sore throats, reported hearing impairment, ear infections). The questionnaire had high internal consistency. Factor analysis showed 4 dimensions in the pattern of responses relating to emotion, physical health, learning, and vitality. The GCBI is a means to retrospectively assess benefit after an intervention in children, and we have shown initial evidence of reliability and validity. Although not restricted to any branch of pediatric medicine, it is eminently suitable for use in pediatric otolaryngology.

Perceptual segregation of competing speech sounds: the role of spatial location.

Culling and Summerfield [J. Acoust Soc. Am. 92, 785-797 (1995)] showed that listeners could not use ongoing interaural time differences (ITDs) to achieve source segregation. The present experiments tested a free-field analog of their experiment. The stimuli consisted of narrow bands of noise, pairs of which represented the first and second formants of the whispered vowels "ar," "ee," "er," and "oo." A target noise-band pair (vowel) was presented at various angles on the listeners' left while a complementary distracter was presented on the listeners' right. Listeners correctly identified the target vowel in the free-field well above chance. Performance remained well above chance in headphone experiments that retained spatial cues but eliminated reverberations and head movements. The full range of cues that normally determine perceived spatial location provided sufficient information for segregation. Further experiments, which systematically evaluated the contribution of these cues in isolation and in combination, showed that some listeners, following training, exhibited the ability to segregate based on ongoing ITDs alone. Substantial individual differences were observed. The results show that listeners can use spatial cues to segregate simultaneous sound sources.