Influence of working memory and attention on sound-quality ratings.

This study investigated the potential influence of cognitive factors on subjective sound-quality ratings. To this end, 34 older subjects (ages 61-79) with near-normal hearing thresholds rated the perceived sound quality of speech and music stimuli that had been distorted by linear filtering, non-linear processing, and multiband dynamic compression. In addition, all subjects performed the Reading Span Test (RST) to assess working memory capacity (WMC), and the test d2-R (a visual test of letter and symbol identification) was used to assess the subjects' selective and sustained attention. The quality-rating scores, which reflected the susceptibility to signal distortions, were characterized by large interindividual variances. Linear mixed modelling with age, high-frequency pure tone threshold, RST, and d2-R results as independent variables showed that individual speech-quality ratings were significantly related to age and attention. Music-quality ratings were significantly related to WMC. Taking these factors into account might lead to improved sound-quality prediction models. Future studies should, however, address the question of whether these effects are due to procedural mechanisms or actually do show that cognitive abilities mediate sensitivity to sound-quality modifications.

Low background noise increases cognitive load in older adults listening to competing speech.

This letter describes a dual-task paradigm sensitive to noise masking at favorable signal-to-noise ratios (SNRs). Two competing sentences differing in voice and context cues were presented against noise at SNRs of +2 and +6 dB. Listeners were asked to repeat back words from both competing sentences while prioritizing one of them. Recognition of the high-priority sentences was high and did not depend on the SNR. In contrast, recognition of the low-priority sentences was low and showed a significant SNR effect that was related to the listener's working memory capacity. This suggests that even subtle noise masking causes cognitive load in competing-talker situations.

Verbal Response Times as a Potential Indicator of Cognitive Load During Conventional Speech Audiometry With Matrix Sentences.

This study examined verbal response times-that is, the duration from stimulus offset to voice onset-as a potential measure of cognitive load during conventional testing of speech-in-noise understanding. Response times were compared with a measure of perceived effort as assessed by listening effort scaling. Three listener groups differing in age and hearing status participated in the study. Testing was done at two target intelligibility levels (80%, 95%) and with two noise types (stationary and fluctuating). Verbal response times reflected effects of intelligibility level, noise type, and listener group. Response times were shorter for 95% compared with 80% target intelligibility, shorter for fluctuating compared with stationary noise, and shorter for young listeners compared with older listeners. Responses were also faster for the older listeners with near normal hearing compared with the older hearing-aid users. In contrast, subjective listening effort scaling predominantly revealed effects of target intelligibility level but did not show consistent noise-type or listener-group effects. These findings show that verbal response times and effort scalings tap into different domains of listening effort. Verbal response times can be easily assessed during conventional speech audiometry and have the potential to show effects beyond performance measures and subjective effort estimates.

Assessment of hearing aid algorithms using a master hearing aid: the influence of hearing aid experience on the relationship between speech recognition and cognitive capacity.

OBJECTIVES: Model-based hearing aid development considers the assessment of speech recognition using a master hearing aid (MHA). It is known that aided speech recognition in noise is related to cognitive factors such as working memory capacity (WMC). This relationship might be mediated by hearing aid experience (HAE). The aim of this study was to examine the relationship of WMC and speech recognition with a MHA for listeners with different HAE. DESIGN: Using the MHA, unaided and aided 80% speech recognition thresholds in noise were determined. Individual WMC capacity was assed using the Verbal Learning and Memory Test (VLMT) and the Reading Span Test (RST). STUDY SAMPLE: Forty-nine hearing aid users with mild to moderate sensorineural hearing loss divided into three groups differing in HAE. RESULTS: Whereas unaided speech recognition did not show a significant relationship with WMC, a significant correlation could be observed between WMC and aided speech recognition. However, this only applied to listeners with HAE of up to approximately three years, and a consistent weakening of the correlation could be observed with more experience. CONCLUSIONS: Speech recognition scores obtained in acute experiments with an MHA are less influenced by individual cognitive capacity when experienced HA users are taken into account.

Effects of Hearing Loss and Cognitive Load on Speech Recognition with Competing Talkers.

Everyday communication frequently comprises situations with more than one talker speaking at a time. These situations are challenging since they pose high attentional and memory demands placing cognitive load on the listener. Hearing impairment additionally exacerbates communication problems under these circumstances. We examined the effects of hearing loss and attention tasks on speech recognition with competing talkers in older adults with and without hearing impairment. We hypothesized that hearing loss would affect word identification, talker separation and word recall and that the difficulties experienced by the hearing impaired listeners would be especially pronounced in a task with high attentional and memory demands. Two listener groups closely matched for their age and neuropsychological profile but differing in hearing acuity were examined regarding their speech recognition with competing talkers in two different tasks. One task required repeating back words from one target talker (1TT) while ignoring the competing talker whereas the other required repeating back words from both talkers (2TT). The competing talkers differed with respect to their voice characteristics. Moreover, sentences either with low or high context were used in order to consider linguistic properties. Compared to their normal hearing peers, listeners with hearing loss revealed limited speech recognition in both tasks. Their difficulties were especially pronounced in the more demanding 2TT task. In order to shed light on the underlying mechanisms, different error sources, namely having misunderstood, confused, or omitted words were investigated. Misunderstanding and omitting words were more frequently observed in the hearing impaired than in the normal hearing listeners. In line with common speech perception models, it is suggested that these effects are related to impaired object formation and taxed working memory capacity (WMC). In a post-hoc analysis, the listeners were further separated with respect to their WMC. It appeared that higher capacity could be used in the sense of a compensatory mechanism with respect to the adverse effects of hearing loss, especially with low context speech.

Hearing aid fitting in older persons with hearing impairment: the influence of cognitive function, age, and hearing loss on hearing aid benefit.

PURPOSE: To examine the association of cognitive function, age, and hearing loss with clinically assessed hearing aid benefit in older hearing-impaired persons. METHODS: Hearing aid benefit was assessed using objective measures regarding speech recognition in quiet and noisy environments as well as a subjective measure reflecting everyday situations captured using a standardized questionnaire. A broad range of general cognitive functions such as attention, memory, and intelligence were determined using different neuropsychological tests. Linear regression analyses were conducted with the outcome of the neuropsychological tests as well as age and hearing loss as independent variables and the benefit measures as dependent variables. Thirty experienced older hearing aid users with typical age-related hearing impairment participated. RESULTS: Most of the benefit measures revealed that the participants obtained significant improvement with their hearing aids. Regression models showed a significant relationship between a fluid intelligence measure and objective hearing aid benefit. When individual hearing thresholds were considered as an additional independent variable, hearing loss was the only significant contributor to the benefit models. Lower cognitive capacity - as determined by the fluid intelligence measure - was significantly associated with greater hearing loss. Subjective benefit could not be predicted by any of the variables considered. CONCLUSION: The present study does not give evidence that hearing aid benefit is critically associated with cognitive function in experienced hearing aid users. However, it was found that lower fluid intelligence scores were related to higher hearing thresholds. Since greater hearing loss was associated with a greater objective benefit, these results strongly support the advice of using hearing aids regardless of age and cognitive function to counter hearing loss and the adverse effects of age-related hearing impairment. Still, individual cognitive capacity might be relevant for hearing aid benefit during an initial phase of hearing aid provision if acclimatization has not yet taken place.