| Project/Area Number |
11671677
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Otorhinolaryngology
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
KANEKO Ken-ichi Kyoto University, medicine, instructor, 医学研究科, 助手 (90283689)
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| Co-Investigator(Kenkyū-buntansha) |
NAGAMINE Takashi Kyoto University, medicine, instructor, 医学研究科, 助手 (10231490)
NAITO Yasushi Kyoto University, medicine, assistant professor, 医学研究科, 講師 (70217628)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2000: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1999: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | sensorineural hearing loss / inner-ear hearing loss / evoked magnetic fields / N100m / loudness recruitment / hyperacusis / auditory cortex / Intensity coding / 語音弁別 / 事象関連脳磁界反応 / 聴覚言語 / 側頭葉 / 補充現象 |
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| Research Abstract |
To examine the speech intelligibility of sensorineural hearing impaired patients, we studied the effects of an impact noise on the speech intelligibility for listeners wearing a hearing aid. Sentences mixed with a single impact noise were presented randomly. The intelligibility of sentences mixed with an impact noise decreased not only after the impact noise, but also before the noise. On the other hand, there was only none or a slight decrease in intelligibility in the normal hearing subjects.These results indicate that incompletely suppressed impact noises mask the speech signal, and thus cause a decrease in the speech recognition of hearing impaired subjects.
To elucidate the cortical representation of loudness recruitment, we measured auditory evoked magnetic fields (AEFs) in patients who had mild to moderate inner-ear hearing loss with loudness recruitment. We presented a 1 kHz pure tone with 40, 50, 60 or 70 dBHL randomly. The dipolemoment of equivalent current dipole (ECD) for N 100m component increased as a function of sound intensity in both groups. The dipolemoment at high stimulus intensities was larger in patients than in normal subjects. In addition, the degree of increase in the dipolemoment was much larger in patients than in normal subjects, particularly in the contralateral hemisphere. The latency of N 100 m at lower sitmulus intensity was longer in patients than in normal subjects. The latency decreased as a function of sound intensity in both groups. The degree of decrease was larger in patients than in normal subjects, particularly in the hemisphere contralateral to the stimulated ear. Neuronal activities participating in the N 100m response may be involved in cortical processing of loudness sensation, and the present results are considered to be compatible with psycho-acoustic characteristics of loudness recruitment or hyperacusis.
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