• 전기학회논문지
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• 제59권4호
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• pp.831-840
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• 2010

In this paper, we propose a hearing impairment simulator considering reduced frequency selectivity and asymmetrical auditory filter of the hearing impaired, and we verified the reduced frequency selectivity and asymmetrical auditory filter affected in speech perception through experiments. The reduced frequency selectivity has made embodied by spectral smearing using LPC(linear prediction coding). The shapes of auditory filter are asymmetrical different with each center frequency. Hearing impaired person which has hearing loss was differently changed with that of normal hearing people and it has different value for speech of quality through auditory filter. The experiments confirmed subjective test and objective test. The subjective experiments are composed of 4 kinds of tests: pure tone test, SRT(speech reception threshold) test, and WRS(word recognition score) test without spectral smearing, and WRS test with spectral smearing. The experiment of the hearing impairment simulator was performed from 9 subjects who have normal ears. The amount of spectral smearing was controlled by LPC order. The asymmetrical auditory filter of proposed hearing impairment simulator was simulated and then some tests to estimate the filter's performance objectively were performed. The objective experiment as simulated auditory filter's performance evaluation method used PESQ(perceptual evaluation of speech quality) and LLR(log likelihood ratio) for speech through auditory filter. The processed speech was evaluated objective speech quality and distortion using PESQ and LLR value. When hearing loss processed, PESQ and LLR value have big difference according to asymmetrical auditory filter in hearing impairment simulator.

• 재활복지공학회논문지
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• 제3권1호
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• pp.27-34
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• 2009

난청인의 청력 손실은 개인별로 다양하므로 기존의 대칭적으로 주파수 밴드별 청각 필터를 구현하는 방법은 다양한 형태의 난청인의 청력 손실을 적절하게 모사해주지 못한다. 각 중심주파수와 음성의 입력크기에 따라 청각 필터의 형태가 비대칭적으로 바뀌고 청력손실이 있는 난청인은 청력 손실에 따라 청각필터의 형태가 정상인들과는 다른 형태로 바뀌게 되며 음질에도 차이가 있다. 본 연구에서는 난청인의 난청 정도에 따라 변하는 비대칭 청각 특성을 잘 반영한 청각필터를 구현하여 몇 가지 실험을 통해 각 구현된 청각 필터의 성능을 객관적으로 평가하였다. 실험은 구현된 청각 필터를 통한 음성의 perceptual evaluation of speech quality (PESQ) 와 log likelihood ratio (LLR)를 사용하였으며 그 값을 통해 처리된 음성의 객관적인 음질과 왜곡정도를 평가 하였다. 청력 손실을 주었을 때 대칭과 비대칭 청각 필터사이의 PESQ 와 LLR 값을 실험해 본 결과 청각 필터 간의 큰 차이를 보였다. 위 실험 결과들로 대칭과 비대칭 청각 필터의 형태에 따라서 음성의 음질에 영향을 받는다는 것을 알 수 있었다. 특히, 난청이 있을 때 중심 주파수별 청각 필터의 비대칭적 형태 변화가 난청인이 받아들이는 음질에 영향이 있었다.

• 한국산업보건학회지
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• 제20권2호
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• pp.94-101
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• 2010

This study was performed to examine the asymmetry of hearing loss among the noise exposed male workers. Findings of otoscopic examination, pure tone audiometry and tympanometry were evaluated for 179 male workers working in the noise exposed workplace. And also selfadministered structured questionnaires were used for each worker's work-related and general characteristics including personal health behaviors. There were significant differences of hearing threshold between right and left ears at 1,000 Hz and 3,000 Hz(p<0.05). And also significant differences of hearing threshold were noted in the age group over 50 at 3,000 Hz, the high risk drinking group either at 3,000 Hz and 4,000 Hz, the work duration group 10-19 years at 3,000 Hz, the noise exposure group under 90 dB(A) at 3,000 Hz, the noise exposure group over 90 dB(A) at 1,000 Hz, the non-wearing protective device group at 4,000 Hz, and the wearing protective device group at 3,000 Hz(p<0.05). Further study is needed to explore the extent and the related factors of the asymmetry of hearing loss in the general population and occupationally noise exposed group.

• 한국산업보건학회지
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• 제17권2호
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• pp.153-159
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• 2007

Usually equal noise exposure is considered to cause symmetrical hearing loss, but some screening audiometries of employees who were exposed to noise showed asymmetry. Therefore, this study was carried out to evaluate the distribution of asymmetrical hearing loss and the difference of air conduction level between left and right ear at the different frequencies (500, 1,000, 2,000, 3,000, 4,000, 6,000 Hz). Study subjects were 326 male employees who had participated in the noise-specific health examination from May to October, 2002. They were evaluated by otoscopic examination, pure tone audiometry and tympanometry. In all frequencies, hearing threshold level of left ear was worse than right ear. The mean interaural threshold differences between two ears were 0.83 dB at 500 Hz, 1.18 dB at 2,000 Hz, 2.29 dB at 3,000 Hz, 2.18 dB at 4,000 Hz, and statistically significant (p<0.05). The hearing loss of left ear was greater than right ear in occupationally noise-exposed workers. It is believed that left ear was more susceptible to noise damage than right ear