[Examination of signals for tinnitus sound therapy. Effects of signal dynamics on sound acceptance and tinnitus masking]. / Untersuchungen von Rauschsignalen für die akustische Tinnitustherapie. Auswirkung von Dynamik auf Akzeptanz und Verdeckungswirkung.

BACKGROUND: In terms of sound acceptance and tinnitus-masking efficacy, tinnitus sound therapy appears to be more effective using dynamic natural sounds than static noise signals. The aim of this study was to systematically determine the effects of physical dynamics parameters on tinnitus masking and sound acceptance. MATERIALS AND METHODS: Based on a dynamic model, noise signals with different dynamic properties were synthesized and used to investigate minimal masking levels (MMLs) and spontaneous sound acceptance in six tinnitus patients. RESULTS: High signal dynamics resulted in high MMLs and low sound acceptance. In some instances, low signal dynamics gave rise to slightly lower MMLs than white noise. Despite unfavourable MMLs, natural dynamic sounds were better accepted than synthesized sounds with comparable dynamics. CONCLUSIONS: The higher spontaneous acceptance of natural sounds as compared to white noise appears not to be due solely to physical sound properties, but rather to result primarily from psychological factors. It may be possible to improve sound acceptance in tinnitus sound therapy by using signals with low amounts of dynamics and implementing the use of natural sounds.

Cognitive resources related to speech recognition with a competing talker in young and older listeners.

Speech recognition in a multi-talker situation poses high demands on attentional and other central resources. This study examines the relationship between age, cognition and speech recognition in tasks that require selective or divided attention in a multi-talker setting. Two groups of normal-hearing adults (one younger and one older group) were asked to repeat utterances from either one or two concurrent speakers. Cognitive abilities were then inspected by neuropsychological tests. Speech recognition scores approached its ceiling and did not significantly differ between age groups for tasks that demanded selective attention. However, when divided attention was required, performance in older listeners was reduced as compared to the younger group. When selective attention was required, speech recognition was strongly related to working memory skills, as determined by a regression model. In comparison, speech recognition for tests requiring divided attention could be more strongly determined by neuropsychological probes of fluid intelligence. The findings of this study indicate that - apart from hearing impairment - cognitive aspects account for the typical difficulties of older listeners in a multi-speaker setting. Our results are discussed in the context of evidence showing that frontal lobe functions in terms of working memory and fluid intelligence generally decline with age.

[Examination of speech perception and cognitive functioning in the elderly]. / Untersuchungen zum Sprachverstehen und zu kognitiven Fähigkeiten im Alter.

BACKGROUND: Elderly persons frequently complain about problems with speech understanding especially in complex acoustic situations. Besides hearing impairment the decline of cognitive functions might explain these problems. METHODS: In 12 normal hearing young subjects and 14 elderly listeners with extraordinarily good hearing speech perception was measured in a broad range of different acoustic situations. Cognitive functioning was evaluated with different neuropsychological tests. RESULTS: Despite comparable pure tone thresholds the elderly listeners revealed worse speech discrimination than the young subjects in almost all test situations. Largest differences were found in situations with fluctuating maskers and competing talkers. Most of the speech perception results revealed significant correlations with the outcome from a neuropsychological test addressing declarative verbal memory. CONCLUSIONS: In complex listening situations elderly persons reveal worse speech understanding than younger subjects. Differences in speech perception can partly be attributed to cognitive abilities. In particular, working memory seems to be an important factor.