**1. Introduction**

16 Will-be-set-by-IN-TECH

66 Hearing Loss

This investigated how the listening scores of an audio signal and the psychological impressions related to speech audibility when listening to the audio signal under conditions of meaningless steady or fluctuating noise change when the frequency characteristics of hearing loss related to aging are taken into account. Specifically, psychological listening experiments by subjects with normal hearing were performed using artificial hearing impairments (frequency filters) that simulated hearing loss. Using the observed data obtained in psychological listening experiments, the relationships between *WSPD* and the listening scores of an audio signal and the psychological impressions related to speech audibility were established using regression models. Further, the effect of hearing loss due to factors such as aging on the listening scores of the audio signal and the psychological impressions related to speech audibility was predicted from the above relationships. Since the predicted values are in good agreement with the observed values, both the validity and the applicability of the proposed method were confirmed experimentally, and reasonable results were obtained.

(1) Since the current study was limited to subjects with normal hearing who experienced artificial hearing impairment with frequency filter-simulated hearing loss, the applicability of the same method to situations where the subjects are actually hearing impaired persons should be confirmed. However, comparing the available data on hearing impaired persons with the results of our simulations of hearing impairment in this study, we can conclude that our study provides fundamental data to aid in determining whether the results of such psychological listening experiments conducted using normal-hearing subjects who experience artificial hearing impairment are as valid as those conducted on

(2) Decreasing pure-tone audiometric thresholds were employed as hearing loss with increasing age. However, it is still necessary to consider other factors, such as loss of frequency selectivity and reduced temporal resolution in peripheral auditory

Tamesue T. ; Yamaguchi S.; Saeki T. Psychological impressions and listening score while

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Yokouchi Y. Studies on the physiological hearing loss by age. *Nippon Jibiinkoka Gakkai Kaiho*

Nakajima T. ; Maeda S. The application of speech transmission index (STI) as a measure

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of Japanese speech audibility. *Proceedings of the Research Committee Meeting on Architectural Acoustics of the Acoustical Society of Japan* No.AA-84-30, 1-8, 1984. Kryter KD. Method for the calculation and use of the articulation index. *The Journal of the*

Future studies should examine the following aspects of this research.

**6. Conclusion**

hearing-impaired subjects.

No.4, 443-457.

normal persons. 1984.

Vol.67, No.9, 1307-1312.

deterioration.

**7. References**

Age-dependent hearing loss involves pathological changes affecting the peripheral as well as the central auditory system. The Mongolian Gerbil is a rodent with an average life span of 3-4 years, which shows, in contrast to mice and rats, sensitive hearing in the frequency range that is important for human communication. Consequently, gerbils have been used to study structural and functional aspects of age-dependent hearing loss at the level of the cochlea and auditory brain stem nuclei. In addition, age-dependent changes in behavioural performance have been characterised for different auditory tasks. We have also analysed the effect of certain drugs on impaired temporal processing in old gerbils. The data from gerbils contribute to a framework that helps to better understand the mechanisms contributing to age-dependent hearing loss and may lead to new pharmacotherapeutic strategies for the treatment of age-dependent central hearing loss.
