Sounds in natural environments, including speech sounds, vary over time. The auditory system extracts information embedded in the temporal variations to recognize speech and environment. This review pertains to methods to evaluate evaluation of the auditory sensitivities to temporal information and the possible auditory mechanisms involved in the analysis of the information. Temporal variation of a sound can be decomposed into an amplitude envelope and a temporal fine structure. The amplitude envelope conveys important information for speech understanding. The gap detection threshold and temporal modulation transfer function are widely used as indices of the auditory sensitivities to the amplitude envelope. The modulation spectrum can be used to describe envelope information. Modulation filter bank is a possible auditory mechanism involved in the analysis of the modulation spectrum. The temporal fine structure contributes to pitch perception and sound localization, as well as to recognition of speech in noisy environments. Alterations of the detailed responses of the basilar membrane and/or reduction of auditory nerve function can significantly degrade auditory sensitivity to the temporal fine structure.
Phonemic restoration is the ability to hear and understand, with the involvement of the brain, sound information made unintelligible by noise. We made hearing young people, hearing elderly people, and hearing-impaired elderly people listen to short sentences in Japanese (Japanese Hearing in Noise Test, HINT-J) under five different conditions, an original listening condition (listening to a sentence without alternation), a condition where silent intervals were inserted, and three noise insertion conditions where noise was inserted into the silent intervals with signal-to-noise ratios of 0, -5, and -10 dB, and evaluated the effects of age and hearing impairment on phonemic restoration. In the elderly subjects, insertion of silent intervals reduced the percentage of correct answers; this tendency was stronger in the hearing-impaired elderly than in the hearing elderly. A phonemic restoration effect from inserted noise was observed in all subjects, and was greater when the inserted noise was louder. Such phonemic restoration effects exhibited no clear association with the background factors in the hearing-impaired individuals' hearing ability, speech articulation, age, threshold values for hearing aids, or speech articulation during use. However, the findings suggested that the complexity of the hearing impairment factors in elderly subjects may have had an impact on the phonemic restoration.
This study on impairment and communication status based on the data of 2,018 deaf-blind older adults from a national survey carried out with the cooperation of 97 local governments in Japan revealed the following. Deaf-blind older adults accounted for 74.6% of people with acquired visual and hearing impairments (visually and hearing impaired, 46.1%; blind and hearing impaired, 25.6%; totally deaf-blind, 10.3%; deaf and visually impaired, 8.9%). Moreover, the proportion of hearing-aid recipients remained at 46.4%, of whom only half were able to understand the speech of a person whom they met for the first time, even with the assistance of hearing aids. Experts who take care of deaf-blind adults need to collaborate to provide information regarding hearing aids and active hearing use. Furthermore, 32.4% of totally deaf-blind adults experienced social isolation, with a conversation frequency of 2 days or less a month. This suggests that systematic expert support should be provided immediately after medical examination of for persons with dual impairment, including information regarding alternative communication modes and rehabilitation.
We established a committee for the investigation of hearing impairment in 2012, with members from? the area support center of Fukushima Prefectural School for the Deaf, Fukushima Special Education Center, Fukushima Rehabilitation Center for Children, Hoshi General Hospital, and Fukushima Medical University Hospital. The committee conducted a survey of teachers in 2012, to determine the learning environment of hearing aid users who went to regular elementary schools in Fukushima Prefecture. The survey revealed that hearing-aid users had problems in listening, academic achievement, and relationships with other students. Furthermore, use of the FM hearing aid system, education environment improvement, education support planning, and teaching planning were not implemented sufficiently. In addition, hearing-aid users were also not provided with appropriate support. The committee therefore decided to apply the following division of roles which had been determined for cochlear-implant and hearing-aid users attending regular junior high schools. The area support center holds case conferences following class observation, where problems are clarified, countermeasures are identified, and questions from teachers are answered. The Fukushima Special Education Center coordinates such support. The Fukushima Rehabilitation Center and the two hospitals provide information on hearing levels and language skills to the support center and Fukushima Special Education Center.
In recent years, attention to sound therapy with hearing aids for the management of tinnitus through television, books and other media has been rapidly increasing. As a result, tinnitus retraining therapy (TRT) using hearing aids has become prevalent. In this article, we report the results of comparison of the clinical findings at the initial visit and clinical course between patients who were able to continue TRT using hearing aids (hereinafter “TRT-continued group”) and those who were unable to continue TRT (hereinafter “TRT-discontinued group”). Of 94 patients (52 males and 42 females) with tinnitus who visited the outpatient clinic for tinnitus and hearing loss of the Department of Otolaryngology, Shin-yurigaoka General Hospital, between April 2012 and March 2014, the data of 24 patients (17 males and 7 females) who were able to continue TRT using hearing aids and 31 patients (15 males and 16 females) who were unable to continue TRT using hearing aids were analyzed. 1. We report the results of comparison of the clinical findings at the initial visit and clinical course between patients who were able to continue TRT using hearing aids and those who were unable to continue TRT. 2. The statistical analysis revealed that the score on the tinnitus handicap inventory (THI) at the initial visit was significantly higher in the TRT-discontinued group than in the TRT-continued group, suggesting that TRT is less likely to be effective in patients with high scores on the THI. 3. The results suggest that the patients' interests need to be aligned and that the counseling frequency during TRT needs to be increased by increasing the frequency of medical consultations, which can be done, for example, by shortening the revisit intervals for TRT and extending the observation period. These findings suggest that for intractable cases, the frequency of medical consultations needs to be increased, for example, by shortening the revisit intervals during TRT and extending the observation period.