• Clinical and Experimental Otorhinolaryngology
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• 제11권4호
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• pp.267-274
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• 2018

Objectives. Two main digital signal processing technologies inside the modern hearing aid to provide the best conditions for hearing aid users are directionality (DIR) and digital noise reduction (DNR) algorithms. There are various possible settings for these algorithms. The present study evaluates the effects of various DIR and DNR conditions (both separately and in combination) on listening comfort among hearing aid users. Methods. In 18 participants who received hearing aid fitting services from the Rehabilitation School of Shahid Beheshti University of Medical Sciences regularly, we applied acceptable noise level (ANL) as our subjective measure of listening comfort. We evaluated both of these under six different hearing aid conditions: omnidirectional-baseline, omnidirectional-broadband DNR, omnidirectional-multichannel DNR, directional, directional-broadband DNR, and directional-multichannel DNR. Results. The ANL results ranged from -3 dB to 14 dB in all conditions. The results show, among all conditions, both the omnidirectional-baseline condition and the omnidirectional-broadband DNR condition are the worst conditions for listening in noise. The DIR always reduces the amount of noise that patients received during testing. The DNR algorithm does not improve listening in noise significantly when compared with the DIR algorithms. Although both DNR and DIR algorithms yielded a lower ANL, the DIR algorithm was more effective than the DNR. Conclusion. The DIR and DNR technologies provide listening comfort in the presence of noise. Thus, user benefit depends on how the digital signal processing settings inside the hearing aid are adjusted.

• Journal of Audiology & Otology
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• 제24권2호
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• pp.91-98
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• 2020

Background and Objectives: This study aimed to compare functional hearing with the use of a personal sound amplification product (PSAP) or a basic hearing aid (HA) among sensorineural hearing impaired listeners. Subjects and Methods: Nineteen participants with mild-to-moderate sensorineural hearing loss (SNHL) (26-55 dB HL; pure-tone average, 0.5-4 kHz) were prospectively included. No participants had prior experience with HAs or PSAPs. Audiograms, speech intelligibility in both quiet and noisy environments, speech quality, and preference were assessed in three different listening conditions: unaided, with the HA, and with the PSAP. Results: The use of PSAP was associated with significant improvement in pure-tone thresholds at 1, 2, and 4 kHz compared to the unaided condition (all p<0.01). In the quiet environment, speech intelligibility was significantly improved after wearing a PSAP compared to the unaided condition (p<0.001), and this improvement was better than the result obtained with the HA. The PSAP also demonstrated similar improvement in the most comfortable levels compared to those obtained with the HA (p<0.05). However, there was no significant improvement of speech intelligibility in a noisy environment when wearing the PSAP (p=0.160). There was no significant difference in the reported speech quality produced by either device or in participant preference for the PSAP or HA. Conclusions: The current result suggests that PSAPs provide considerable benefits to speech intelligibility in a quiet environment and can be a good alternative to compensate for mild-to-moderate SNHL.

• 대한청각학회지
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• 제24권2호
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• pp.91-98
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• 2020

Background and Objectives: This study aimed to compare functional hearing with the use of a personal sound amplification product (PSAP) or a basic hearing aid (HA) among sensorineural hearing impaired listeners. Subjects and Methods: Nineteen participants with mild-to-moderate sensorineural hearing loss (SNHL) (26-55 dB HL; pure-tone average, 0.5-4 kHz) were prospectively included. No participants had prior experience with HAs or PSAPs. Audiograms, speech intelligibility in both quiet and noisy environments, speech quality, and preference were assessed in three different listening conditions: unaided, with the HA, and with the PSAP. Results: The use of PSAP was associated with significant improvement in pure-tone thresholds at 1, 2, and 4 kHz compared to the unaided condition (all p<0.01). In the quiet environment, speech intelligibility was significantly improved after wearing a PSAP compared to the unaided condition (p<0.001), and this improvement was better than the result obtained with the HA. The PSAP also demonstrated similar improvement in the most comfortable levels compared to those obtained with the HA (p<0.05). However, there was no significant improvement of speech intelligibility in a noisy environment when wearing the PSAP (p=0.160). There was no significant difference in the reported speech quality produced by either device or in participant preference for the PSAP or HA. Conclusions: The current result suggests that PSAPs provide considerable benefits to speech intelligibility in a quiet environment and can be a good alternative to compensate for mild-to-moderate SNHL.

• 한국정보전자통신기술학회논문지
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• 제9권2호
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• pp.205-212
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• 2016

본 논문에서는 Matlab에서 제공하는 Simulink를 활용하여 다채널 디지털 보청기 알고리즘 개발 플랫폼의 구현을 제안하였다. 디지털 보청기는 난청자의 원활한 의사소통을 돕는 의료기구로 그 중요성이 날로 증가하고 있다. 특히 다채널 디지털 보청기는 난청자의 주파수 별 청력 손실 정도에 따른 보상이 가능해 고막의 손상을 최소화하는 동시에 보청기 사용자에게 적합한 증폭이 가능해진다. 본 논문에서 구현한 개발 플랫폼은 WOLA 필터뱅크를 이용해 입력 신호의 분석 및 합성이 이루어지며 광역동범위압축(Wide Dynamic ragne compression) 기반의 난청 보상 알고리즘, 적응 필터를 이용한 음향 궤환 제거 알고리즘(Adaptive feedback cancellation)을 포함한다. Simulink를 이용한 개발 플랫폼에서 각 블록의 파라미터를 설정 할 수 있고 블록별 결과가 확인이 가능하다. 이를 이용해 기계어 코딩 전 단계에서 알고리즘 테스트가 가능하기 때문에 보청기 알고리즘의 개발 시간이 단축 가능하고 계산량 및 성능 최적화가 가능해졌다.

• 말소리와 음성과학
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• 제6권2호
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• pp.55-64
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• 2014

This study measured formant bandwidths of profound hearing impaired children and examined the characteristics of their articulation. For this study, 10 cochlear implanted children(CI), 10 hearing aid children(HA) and 10 normal hearing children(NH) were asked to read 7 Korean vowels(/ɑ, ʌ, o, u, ɯ, i, ɛ/). The subjects' readings were recorded by NasalView and analyzed by Praat. The analysis of the formant bandwidths explains the degree of vocal fold opening and the characteristics of radiation. Through the analysis of formant bandwidth, we can see that the hearing-impaired maintain vocal fold tension when they speak high vowels and characteristics of radiation. Narrower B1 means better maintain vocal fold tension, wider B2 means more front and wider B3 means the rounder lips. CI's B1 was widest and NH's was narrowest. And females' B1 was wider than males'. Among vowels, B1 of /a/ was widest, and B1 of /i/ was narrowest. In the case of B2, HA and NH's B2 was wider than CI's. Females' B2 was wider than males'. And B2 of /i/ was widest, and B2 of /ʌ/ was narrowest. In the case of B3, NH's was widest, and CI's was narrowest. Males' was wider than females'. Among vowels, B3 of /o/ was widest, and B3 of /ɛ/ was narrowest. As a result, first, through the analysis of B1, we can find that NH and males could better maintain vocal fold tension than the hearing-impaired or females, and all children articulate /i/ with vocal fold tension than other vowels. Second, through the analysis of B2, NH and HA articulate vowels with the weaker rounded than CI does. And females articulate vowels with the weaker rounded than males do. Third, through the analysis of B3, NH articulate vowels with the rounder than HA or CI do, and males articulate vowels with the rounder than females do. Through the results, we can expect that the analysis of formant bandwidth will be applied to the therapy of articulation for the hearing-impaired with hearing aids or cochlear implant.

• 대한청각학회지
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• 제25권2호
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• pp.72-79
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• 2021

Background and Objectives: The speech-in-noise test is typically performed using an audiometer. The results of the digit-in-noise recognition (DIN) test may be influenced by the flat frequency response of free-field audiometry and frequency of the hearing aid fit based on fitting rationale. This study aims to investigate the DIN test in unaided and aided conditions. Subjects and Methods: Thirty four adults with moderate and severe sensorineural hearing loss (SNHL) participated in the study. The signal-to-noise ratio (SNR) for 50% of the DIN test was obtained in the following two conditions: 1) the unaided condition, performed using an audiometer in a free field; and 2) aided condition, performed using a hearing aid with an unvented individual earmold that was fitted based on NAL-NL2. Results: There was a statistically significant elevation in the mean SNR for the severe SNHL group in both test conditions when compared with that of the moderate SNHL group. In both groups, the SNR for the aided condition was significantly lower than that of the unaided condition. Conclusions: Speech recognition in hearing-impaired patients can be realized by fitting hearing aids based on evidence-based fitting rationale rather than by measuring it using free-field audiometry measurement that is utilized in a routine clinic setup.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.457-460
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• 2005

When a hearing aid' s user is listening through telephone or cellular phone, he/she usually suffers from severe electrical magnetic interference noise. It is because hearing aids amplify voice signal as well as background noise. A telecoil, an induction coil, is a possible solution for the problem. Because a telecoil has the characteristic of high pass filter, it has some problem of resulting increased high frequency noise. For solving this problem, we can use a capacitor connected with the telecoil in parallel. According to capacitance, receiving signal quality may change. In this paper, proper capacitor values for the best sound quality are investigated by experimental work.

• 한국음향학회지
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• 제18권4호
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• pp.38-46
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• 1999

본 논문에서는 보청기에서의 적응궤환 제거 성능을 개선하기 위한 방법들을 제안하였다. 첫번째 방법은 순시 경사치를 모니터링하여 최적해를 추적해 가는 것으로 직교원리를 이용한 음향학적 궤환제거 방법이고 다른 하나는 본 실험실에서 제안된 적응 알고리즘인 보상기를 가진 적응알고리즘을 이용한 방법이다. 다양한 시뮬레이션 조건하에서 본 논문에서 제안된 적응 궤환제거 방법이 Greenberg가 제안한 합-방식(Sum-method) 최소자승오차 알고리즘 보다 시스템 부정합, 신호대 잡음비(SNR: Signal-to-Noise Ratio) 및 세그멘트 SNR에서 훨씬 좋은 성능을 나타내었다. 또한 적응 궤환제거에 있어서 직교원리를 이용한 방법은 시뮬레이션에서 보상기를 가진 적응알고리즘을 이용한 방법과 유사한 성능을 나타내었다.

• 한국통신학회논문지
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• 제35권1C호
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• pp.96-102
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• 2010

본 논문에서는 보청기의 음향궤환 및 잡음을 제거시키기 위한 새로운 알고리즘을 제안하였다. 이 알고리즘은 2개의 마이크를 사용하여 궤환제거 필터의 계수를 갱신시키는 잔차신호에서 음성신호를 제거함으로서 수렴성능을 향상시킨다. 먼저 궤환제거기가 마이크 신호에서 궤환신호를 제거하고, 이어서 빔포밍 기법을 이용하여 잡음을 제거한다. 본 연구에서 제안한 궤환 및 잡음제거기의 성능을 검증하기 위하여 시뮬레이션 프로그램을 작성하고 모의실험을 수행하였다. 실험 결과, 제안한 적응 알고리즘을 사용하면 궤환제거기와 잡음제거기에서 각각 약 14.43 dB의 SFR 및 10.19 dB의 SNR 지수가 개선되는 것을 확인하였다.

• 한국정보통신학회논문지
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• 제12권5호
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• pp.887-892
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• 2008

최근 고령화 사회로 접어들면서 보청기의 수요가 점차 증대되고 있으며, 이에 따라 우수한 성능의 음향궤환제거기가 요구되고 있다. 본 논문에서는 음향궤환제거기의 수렴 특성을 향상시키기 위한 새로운 적응 알고리즘을 제안하였다. 이 알고리즘은 음성신호와 같이 상관도가 높은 신호를 사용하여 적응필터의 계수를 갱신할 때 신호의 상관도를 감소시켜주기 위해 비상관기를 사용함으로서 수렴성능을 향상시킨다. 본 연구에서 제한 음향궤환제거기의 성능을 검증하기 위하여 시뮬레이션 프로그램을 작성하고 시뮬레이션을 수행하였다. 입력신호의 종류와 적응 알고리즘에 따라서 궤환제거기의 수렴특성을 관찰하였다. 시뮬레이션 결과, 제안한 궤환제거기는 유색신호를 입력으로 사용하는 경우, 약 5-10 dB의 SNR 성능이 개선되는 것을 보여 주었다.