Elderly Hearing-impaired Subjects Research Articles

Audiomotor Perceptual Training Enhances Speech Intelligibility in Background Noise

Sensory and motor skills can be improved with training, but learning is often restricted to practice stimuli. As an exception, training on closed-loop (CL) sensorimotor interfaces, such as action video games and musical instruments, can impart a broad spectrum of perceptual benefits. Here we ask whether computerized CL auditory training can enhance speech understanding in levels of background noise that approximate a crowded restaurant. Elderly hearing-impaired subjects trained for 8weeks on a CL game that, like a musical instrument, challenged them to monitor subtle deviations between predicted and actual auditory feedback as they moved their fingertip through a virtual soundscape. We performed our study as a randomized, double-blind, placebo-controlled trial by training other subjects in an auditory working-memory (WM) task. Subjects in both groups improved at their respective auditory tasks and reported comparable expectations for improved speech processing, thereby controlling for placebo effects. Whereas speech intelligibility was unchanged after WM training, subjects in the CL training group could correctly identify 25% more words in spoken sentences or digit sequences presented in high levels of background noise. Numerically, CL audiomotor training provided more than three times the benefit of our subjects' hearing aids for speech processing in noisy listening conditions. Gains in speech intelligibility could be predicted from gameplay accuracy and baseline inhibitory control. However, benefits did not persist in the absence of continuing practice. These studies employ stringent clinical standards to demonstrate that perceptual learning on a computerized audio game can transfer to "real-world" communication challenges.

Subjective Listening Effort and Electrodermal Activity in Listening Situations with Reverberation and Noise.

Disturbing factors like reverberation or ambient noise can impair speech recognition and raise the listening effort needed for successful communication in daily life. Situations with high listening effort are thought to result in increased stress for the listener. The aim of this study was to explore possible measures to determine listening effort in situations with varying background noise and reverberation. For this purpose, subjective ratings of listening effort, speech recognition, and stress level, together with the electrodermal activity as a measure of the autonomic stress reaction, were investigated. It was expected that the electrodermal activity would show different stress levels in different acoustic situations and might serve as an alternative to subjective ratings. Ten young normal-hearing and 17 elderly hearing-impaired subjects listened to sentences from the Oldenburg sentence test either with stationary background noise or with reverberation. Four listening situations were generated, an easy and a hard one for each of the two disturbing factors, which were related to each other by the Speech Transmission Index. The easy situation resulted in 100% and the hard situation resulted in 30 to 80% speech recognition. The results of the subjective ratings showed significant differences between the easy and the hard listening situations in both subject groups. Two methods of analyzing the electrodermal activity values revealed similar, but nonsignificant trends. Significant correlations between subjective ratings and physiological electrodermal activity data were observed for normal-hearing subjects in the noise situation.

Central Auditory Processing Disorders: Effects of Age and Hearing Loss to Electrophysiological and Behavioral Responses

Central Auditory Processing Disorders: Effects of Age and Hearing Loss to Electrophysiological and Behavioral Responses Introduction. Central auditory processing involve normal sound perception, speech recognition, ability of cognition and memory. Accordingly speech recognition difficulties may manifest due to changes at any segment of auditory processing. Cortical auditory evoked potentials (CAEPs) and behavioral measures provide insight into the neural mechanisms underlying speech recognition. These disorders are observed both in young and elderly population. Aim of the study. To evaluate central auditory processing for subjects of different age and hearing level through the presentation of noise using CAEPs and behavioral measures of speech discrimination. However due to complicated connectivity in auditory pathway it is difficult to identify the central auditory processing damage. Behavioral tests in conjunction with electrophysiological examination will reveal more complicated information for differenciation between peripheral and central auditory processing disorders. Materials and methods. Three groups of subjects participated: young normal hearing, young hearing-impaired and elderly hearing-impaired subjects. To minimaze subject variables, the CAEPs (wave peaks P1, N1, P2, N2, P3, N3 in miliseconds) was investigated using passive listening paradigme. The CAEPs were elicited by 1,1s change in frequency 1000 Hz and 2000 Hz in pure tones presented at 65, 70 and 75 dB SPL. Sentence recognition tests in quite and noise, Digit Pairs (DP) and Word Pairs (WP) were developed in Latvian language prior to investigation. They were presented to all subjects. Results. The most prominent finding was the increased latency of P3, N3 in elderly and also in younger hearing impaired adults groups and highly differed within groups. More prolonged latencies were find of N1, P2 in elderly hearing impaired group than in younger hearing impaired group adults. Conclusions. During this investigation the CAEPs are performed for the first time in our clinic therefore the main standarts are determined for our laboratory. The speech recognition tests (Sentence recognition test, DD, DW) are developed in Latvian. The present findings suggest patterns of CAEP are variable within individuals however shows that auditory perception and cognitive function is not only a result of aging and must be associated with a general slowing of neuronal processing or decreased neuronal synchrony within the central auditory nervous system. Determination of central auditory processing capacity level is of crucial significance to prognose and evaluate the hearing result after hearing prosthetics and to appraise indications for hearing prosthetics, cochlear and middle ear implantation including.

The interference of different background noises on speech processing in elderly hearing impaired subjects

The objective of the investigation is to study the interference of different background noises on speech processing. For this purpose speech recognition with the Hagerman test and a test battery with speech comprehension tasks (SVIPS) were performed in speech-weighted background noises varying in temporal structure, signal-to-noise ratio (SNR), and meaningfulness. With different test criteria and a score of perceived effort, the aim was to get a more complete picture of speech comprehension under adverse listening situations. Twenty-four subjects, aged 56–83 years, with a bilateral sensorineural hearing impairment, participated in the study. Differences in performance between the different background noises varied depending on the speech processing task, SNR, and on quantitative versus qualitative outcome measures. Age effects were seen in the Hagerman test and especially in background conditions of modulated noises (speech and reversed speech). Findings are discussed in relation to a hypothesis suggesting that masking and distraction interference from background noises on speech processing at peripheral, central auditory, and cognitive levels depends on the SNR used and the noise type and the listening task.

Auditory measures of selective and divided attention in young and older adults using single-talker competition

In this study, two experiments were conducted on auditory selective and divided attention in which the listening task involved the identification of words in sentences spoken by one talker while a second talker produced a very similar competing sentence. Ten young normal-hearing (YNH) and 13 elderly hearing-impaired (EHI) listeners participated in each experiment. The type of attention cue used was the main difference between experiments. Across both experiments, several consistent trends were observed. First, in eight of the nine divided-attention tasks across both experiments, the EHI subjects performed significantly worse than the YNH subjects. By comparison, significant differences in performance between age groups were only observed on three of the nine selective-attention tasks. Finally, there were consistent individual differences in performance across both experiments. Correlational analyses performed on the data from the 13 older adults suggested that the individual differences in performance were associated with individual differences in memory (digit span). Among the elderly, differences in age or differences in hearing loss did not contribute to the individual differences observed in either experiment.

Age-related differences in identification and discrimination of temporal cues in speech segments

This study investigated age-related differences in sensitivity to temporal cues in modified natural speech sounds. Listeners included young noise-masked subjects, elderly normal-hearing subjects, and elderly hearing-impaired subjects. Four speech continua were presented to listeners, with stimuli from each continuum varying in a single temporal dimension. The acoustic cues varied in separate continua were voice-onset time, vowel duration, silence duration, and transition duration. In separate conditions, the listeners identified the word stimuli, discriminated two stimuli in a same-different paradigm, and discriminated two stimuli in a 3-interval, 2-alternative forced-choice procedure. Results showed age-related differences in the identification function crossover points for the continua that varied in silence duration and transition duration. All listeners demonstrated shorter difference limens (DLs) for the three-interval paradigm than the two-interval paradigm, with older hearing-impaired listeners showing larger DLs than the other listener groups for the silence duration cue. The findings support the general hypothesis that aging can influence the processing of specific temporal cues that are related to consonant manner distinctions.

Effects of Age, Age-Related Hearing Loss, and Contralateral Cafeteria Noise on the Discrimination of Small Frequency Changes: Psychoacoustic and Electrophysiological Measures

The aim of the study was to examine central auditory processes compromised by age, age-related hearing loss, and the presentation of a distracting cafeteria noise using auditory event-related potentials (ERPs). In addition, the relation of ERPs to behavioral measures of discrimination was investigated. Three groups of subjects participated: young normal hearing, elderly subjects with normal hearing for their age, and elderly hearing-impaired subjects. Psychoacoustic frequency discrimination thresholds for a 1000-Hz pure tone were determined in quiet and in the presence of a contralateral cafeteria noise. To elicit ERPs, small frequency contrasts were presented with and without noise under unattended and attended conditions. In the attended condition, behavioral measures of d' detectability and reaction times were also obtained. Noise affected all measures of behavioral frequency discrimination significantly. Except N1, all ERP components in the standard and difference waveforms decreased significantly in amplitude and increased in latency to the same degree in all three subject groups, arguing against a specific age-related sensitivity to the effects of contralateral background noise. For N1 amplitude, the effect of noise was different in the three subject groups, with a complex interaction of age, hearing loss, and attention. Behavioral frequency discrimination was not affected by age but deteriorated significantly in the elderly subjects with hearing loss. In the electrophysiological test, age-related changes occurred at various levels. The most prominent finding in the response to the standard stimuli was a sustained negativity (N2) following P2 in the young subjects that was absent in the elderly, possibly indicating a deficit in the inhibition of irrelevant information processing. In the attended difference waveform, significantly larger N2b and smaller P3b amplitudes and longer N2b and P3b latencies were observed in the elderly indicating different processing strategies. The pronounced age-related changes in the later cognitive components suggest that the discrimination of difficult contrasts, although behaviorally maintained, becomes more effortful in the elderly.

Contribution of consonant versus vowel information to sentence intelligibility by normal and hearing-impaired listeners

The purpose of this study was to examine the contribution of information provided by vowels versus consonants to sentence intelligibility in young normal-hearing (YNH) and elderly hearing-impaired (EHI) listeners. Sentences were presented in three conditions, with either the vowels or the consonants replaced with speech shaped noise, or unaltered. Sentences from male and female talkers in the TIMIT database were selected. EHI subjects listened at 95 dB SPL, and YNH subjects at both 95 and 70 dB SPL. Subjects listened to each sentence twice and were asked to repeat the entire sentence after each presentation. Words were scored correct if identified exactly. Average performance for unaltered sentences was greater than 94%. Vowel-present conditions were always significantly more intelligible than consonant-present conditions, similar to data reported by Cole and colleagues [Proceedings of ICASSP, 1996]. Across groups, performance in the vowel-present conditions exceeded that in the consonant-present conditions by 14% to 40%, although EHI subjects performed more poorly than YNH subjects. In contrast to written English, vowels in spoken language carry more information about sentences than consonants for both normal and hearing-impaired listeners. [Work supported by NIDCD-02229.]

Perceptual auditory stream segregation of sequences of complex sounds in subjects with normal and impaired hearing.

The influence of hearing loss and aging on the perceptual organization of sound sequences was investigated by comparing the ability of young normal-hearing subjects and elderly subjects having either impaired or normal hearing for their age to form perceptual auditory streams from sequences of harmonic complex tones as a function of differences in fundamental frequency (F0). The sequences consisted of repeating triplets of harmonic complex tones separated by a silence (ABA-). In conditions in which the F0s of the A and B tone were so low that the harmonics could not be individually resolved by the peripheral auditory system even in the young normal-hearing subjects, those subjects showed similar stream segregation performance to the elderly hearing-impaired subjects. In contrast, when the F0s of the tones were high enough for the harmonics to be largely resolved at the auditory periphery in normal-hearing subjects, but presumably unresolved in the elderly subjects, the former showed significantly more stream segregation than the latter. These results, which cannot be consistently explained in terms of age differences, suggest that auditory stream segregation is adversely affected by reduced peripheral frequency selectivity of elderly individuals. This finding has implications for the understanding of the listening difficulties experienced by elderly individuals in cocktail-party situations.

The relation between identification and discrimination of vowels by young normal-hearing and elderly hearing-impaired listeners

Four young normal-hearing (YNH) and four elderly hearing-impaired subjects (EHI) with moderate sloping sensori-neural hearing losses participated in vowel-identification and formant-discrimination tasks. To examine the relationship between vowel-identification and formant-discrimination abilities in conditions differing in audibility, signals were presented at two levels (70 and 95 dB SPL). Four mid-vowels (/I/, /e/, /ε/, and /æ/) were chosen as the target signals for both tasks. Identification performance for the YNH subjects was near ceiling performance. The EHI subjects averaged 80% for the 95 dB and 69% for the 70 dB SPL presentation level, although individual subject variability was high. Equivalent discrimination performance in the F1 region (ΔF threshold approximately 30 Hz) was observed for all four vowels, between groups and across levels. In the F2 region the EHI subjects’ thresholds were elevated compared to the YNH subjects at both levels, even when the formants appeared to be fully audible (at 95 dB SPL). Correlational analyses suggested that vowel identification was partially predicted by reduced ability to discriminate spectral differences in the F2 region (at higher frequencies) as well as the subjects’ hearing loss. [Work supported by NIH and NIA.]

Dispositional optimism, dysphoria, health, and coping with hearing impairment in elderly adults.

Sixty-eight elderly hearing impaired subjects were interviewed and completed self-report measures on hearing disability, dispositional optimism, dysphoria, and general health. The measures used were the Hearing Coping Assessment (HCA), the Hearing Questions (HQ), the Life Orientation Test (LOT), The Beck Depression Inventory (BDI), and a subscale from the Göteborg Quality of Life (GQL). Psychometric analyses of HCA, HQ, LOT, BDI, and GQL revealed high reliability in terms of Cronbach's Alpha and split-half r's. Significant intercorrelations were found between several measures, but not with pure-tone audiometry (0.5, 1, 2, and 3 kHz). Cluster analysis was used to identify subgroups in the sample. As a result three clusters were identified interpreted as 'high copers', 'copers with moderate psychological and somatic complaints', and 'low copers'. Results from the cluster analyses were confirmed by using two different clustering methods and by between-cluster comparisons on the HQ, which had not been used to obtain the clusters.

Masking of speech by amplitude-modulated noise.

The masking of speech by amplitude-modulated and unmodulated speech-spectrum noise has been evaluated by the measurement of monaural speech recognition in such noise on young and elderly subjects with normal-hearing and elderly hearing-impaired subjects with and without a hearing aid. Sinusoidal modulation with frequencies covering the range 2-100 Hz, as well as an irregular modulation generated by the sum of four sinusoids in random phase relation, was used. Modulation degrees were 100%, +/- 6 dB, and +/- 12 dB. Root mean-square sound pressure level was equal for modulated and unmodulated maskers. For the normal-hearing subjects, essentially all types of modulated noise provided some release of speech masking as compared to unmodulated noise. Sinusoidal modulation provided more release of masking than the irregular modulation. The release of masking increased with modulation depth. It is proposed that the number and duration of low-level intervals are essential factors for the degree of masking. The release of masking was found to reach a maximum at a modulation frequency between 10 and 20 Hz for sinusoidal modulation. For elderly hearing-impaired subjects, the release of masking obtained from amplitude modulation was consistently smaller than in the normal-hearing groups, presumably related to changes in auditory temporal resolution caused by the hearing loss. The average speech-to-noise ratio required for 30% correct speech recognition varied greatly between the groups: For young normal-hearing subjects it was -15 dB, for elderly normal-hearing it was -9 dB, for elderly hearing-impaired subjects in the unaided listening condition it was +2 dB and in the aided condition it was +3 dB. The results support the conclusion that within the methodological context of the study, age as well as sensorineural hearing loss, as such, influence speech recognition in noise more than what can be explained by the loss of audibility, according to the audiogram and the masking noise spectrum.

Prediction of benefit from linear hearing aids in nonreverberant listening environments.

Hearing aid benefit, defined in terms of improved speech intelligibility, was measured for 16 elderly hearing-impaired subjects. Twelve conditions were tested, simulating a range of daily situations from typical home environments to moderate-sized social gatherings, and assuming a small talker-listener distance (thus maintaining essentially nonreverberant listening conditions). Each subject was fitted with the same type of programmable hearing aid. The goals were to develop a model for the prediction of benefit based on hearing loss, listening environment, and amplification variables, and to assess the potential accuracy of the model. Two models were developed using multiple linear regression analyses. The prefitting model used data that would be available before a hearing aid fitting, that is, audiogram and listening environment data. This model, although potentially useful as a counseling tool, was relatively inaccurate. Six of the 16 subjects yielded benefit data that were consistently different from the model's predictions. The postfitting model used information that could be obtained during a hearing aid fitting about audibility changes resulting from amplification. This model produced more accurate, but still imperfect predictions of benefit. Benefit obtained by three subjects deviated substantially from the predictions of the postfitting model. It was concluded that a model producing fairly accurate benefit predictions must encompass additional variables beyond those considered here. Nevertheless, these models may be useful for prediction of typical benefit for potential hearing aid wearers.

Auditory filter shapes at low center frequencies in young and elderly hearing-impaired subjects

Auditory filter shapes were measured for two groups of hearing-impaired subjects, young and elderly, matched for audiometric loss, for center frequencies (fc) of 100, 200, 400, and 800 Hz using a modified notched-noise method [B. R. Glasberg and B. C. J. Moore, Hear. Res. 47, 103-138 (1990)]. Two noise bands, each 0.4fc wide, were used; they were placed both symmetrically and asymmetrically about the signal frequency to allow the measurement of filter asymmetry. The overall noise level was either 77 or 87 dB SPL. Stimuli were delivered monaurally using Sennheiser HD424 earphones. Although auditory filters for the hearing-impaired subjects were generally broader than for normally hearing subjects [Moore et al., J. Acoust. Soc. Am. 87, 132-140 (1990)], some hearing-impaired subjects with mild losses had normal filters. The filters tended to broaden with increasing hearing loss. There were not any clear differences in filter characteristics between young and elderly hearing-impaired subjects. The signal-to-noise ratios at the outputs of the auditory filters required for threshold (K) tended to be lower than normal for the young hearing-impaired subjects, but were not significantly different from normal for the elderly hearing-impaired subjects. The lower K values for the young hearing-impaired subjects may occur because broadened auditory filters reduce the deleterious effects on signal detection of fluctuations in the noise.

Use and Benefit of Hearing Aids in the Tenth Decade - and Beyond

The purpose of this study was to evaluate the use and benefit of hearing aids in 185 hearing-disabled subjects born before 1900, consecutively fitted with a hearing aid during the first 6 months of 1989. Information from 138 (75%) subjects, 117 females and 21 males with a median age of 93 years (range 90-107), was obtained from a questionnaire, which was mailed 4-6 months after the fitting procedure. The questionnaire included questions concerning use of the hearing aid(s), self-reported benefit, handling problems, overall satisfaction/dissatisfaction, social and domiciliary situation and self-reported visual capacity. Among these elderly subjects 75% had previously been provided with hearing aids, while 25% were first-time users. The results demonstrate that 76% use the hearing aid(s) at home and in small groups, and that 51% use the hearing aid(s) each day; however, 35% did not respond to this question. 64% expressed general satisfaction with their aid(s). Despite instruction and counselling, handling problems were frequently present. In those previously fitted with hearing aids a higher rate of time-related use and satisfaction was present, and handling problems were less frequent than in the first-time applicants. It is concluded that elderly hearing-impaired subjects in the tenth decade use and benefit from hearing aids; however, more problems concerning use and benefit of hearing aids are present in this age group than in the younger age groups.

Speech-Recognition Difficulties of the Hearing-Impaired Elderly

The role that sensorineural hearing loss plays in the speech-recognition difficulties of the hearing-impaired elderly is examined. One approach to this issue was to make between-group comparisons of performance for three groups of subjects: (a) young normal-hearing adults; (b) elderly hearing-impaired adults; and (c) young normal-hearing adults with simulated sensorineural hearing loss equivalent to that of the elderly subjects produced by a spectrally shaped masking noise. Another approach to this issue employed correlational analyses to examine the relation between audibility and speech recognition within the group of elderly hearing-impaired subjects. An additional approach was pursued in which an acoustical index incorporating adjustments for threshold elevation was used to examine the role audibility played in the speech-recognition performance of the hearing-impaired elderly. A wide range of listening conditions was sampled in this experiment. The conclusion was that the primary determiner of speech-recognition performance in the elderly hearing-impaired subjects was their threshold elevation.

Effects of acoustic modification on consonant recognition by elderly hearing-impaired subjects.

In a recent study [S. Gordon-Salant, J. Acoust. Soc. Am. 80, 1599-1607 (1986)], young and elderly normal-hearing listeners demonstrated significant improvements in consonant-vowel (CV) recognition with acoustic modification of the speech signal incorporating increments in the consonant-vowel ratio (CVR). Acoustic modification of consonant duration failed to enhance performance. The present study investigated whether consonant recognition deficits of elderly hearing-impaired listeners would be reduced by these acoustic modifications, as well as by increases in speech level. Performance of elderly hearing-impaired listeners with gradually sloping and sharply sloping sensorineural hearing losses was compared to performance of elderly normal-threshold listeners (reported previously) for recognition of a variety of nonsense syllable stimuli. These stimuli included unmodified CVs, CVs with increases in CVR, CVs with increases in consonant duration, and CVs with increases in both CVR and consonant duration. Stimuli were presented at each of two speech levels with a background of noise. Results obtained from the hearing-impaired listeners agreed with those observed previously from normal-hearing listeners. Differences in performance between the three subject groups as a function of level were observed also.

Effects of room reverberation and noise on speech discrimination by the elderly.

Speech discrimination performance was measured in sound field for 10 young normal-hearing subjects, 10 elderly 'normal-hearing' subjects with a mean pure-tone average of 9.9 dB HTL, and 10 elderly hearing-impaired subjects with a mean pure-tone average of 48.5 dB HTL. Speech discrimination abilities were assessed in quiet and noise (S/N = +10 dB) in a sound suite and under two levels of reverberation in a reverberant room (RT = 0.59 and 1.56 s). Results indicated that the elderly 'normal-hearing' and young normal-hearing subjects have similar speech discrimination performance in the sound suite for both the quiet and noise conditions. In addition, performance by these two groups was almost identical under both levels of reverberation in quiet. However, when noise was added to the reverberant conditions, performance by the elderly 'normal-hearing' subjects was significantly poorer than that obtained by the young normal-hearing subjects. The elderly hearing-impaired subjects yielded speech discrimination scores that were significantly poorer than the elderly 'normal-hearing' subjects and the young normal-hearing subjects for all of the listening conditions.

Differences in speech discrimination in the elderly as a function of type of competing noise: speech-babble or cafeteria.

Speech discrimination of place-loaded Modified Rhyme test words in speech-babble and cafeteria noise by elderly hearing-impaired subjects was measured. The stimuli were presented under the following conditions: (1) monotic: the signal was presented to the preferred ear; (2) low-frequency attenuated: the frequency band below 1,000 Hz was attenuated by 5, 10, and 15 dB relative to the high-frequency band; (3) dichotic: the frequency band above 1,000 Hz was presented to the preferred ear and the low-frequency band to the other ear; (4) diotic: the same signal was presented to both ears. Difference scores between the monotic baseline condition and the other listening modes were calculated and compared. Relationships between listening modes differed as a function of type of competing noise. Low-frequency attenuation improved discrimination in speech-babble but not in cafeteria noise. Dichotic-monotic and diotic-monotic superiority were seen with both noises.