저주파수 영역에 민감한 Amphibian Papilla 청신경의 주파수 특성에 관한 연구

임덕환 대한이비인후과학회 1996 대한이비인후과학회지 두경부외과학 Vol.39 No.7

시간-주파수 변환 압축에 따른 정상 성인의 한국어 단음절 숫자 인지 기능

임덕환,원유경 한국청각언어재활학회 2012 Audiology and Speech Research Vol.8 No.2

There have been constant demands on effective compression schemes for speech signals in both clinical and commercial applications. The effects of these strategies on word recognition tasks appeared to be dependent on the implemented algorithm of the compression, the features of the speech, and the properties of the auditory processing system. It, therefore, is necessary to evaluate the effects of compression schemes on individual languages. However, the related standard data for Korean words were limited in number and this might lead to the inadequate application of the particular compression scheme. In this study, the properties of a typical time-frequency altered compression scheme were analyzed for Korean quintet monosyllabic digit sets in normal hearing young adults. The representative basic compression scheme was based on the time-frequency altered compression preserving no particular traits (PNT) in spectro-temporal domain. Twenty normal hearing young adult subjects (10 males, 10 females) were evaluated for this scheme with the predetermined compression ratios of 1 (no compression), 0.71, 0.5, 0.33, and 0.25. These randomized quintet stimuli were presented to the subjects through acoustically calibrated insert earphones in a custom-made auditory workstation. The results showed rapid deterioration of performance for the corresponding high compression ratios. No statistically significant differences were observed for male and female subjects in the outcomes of the five compression ratios (p > 0.05). In the response profile of PNT, the estimated compression ratio for 50% performance was about 0.44. In summary, a typical time-frequency altered compression scheme (PNT) showed a poor performance near the point where the amount of compression was doubled. This, however, may not indicate the same results for optimized time-frequency features. Thus, profiles of individual compression schemes need to be clinically evaluated and compared for their efficiency and effectiveness.

Markov 신호처리 모델을 응용한 청각재활 프로그램 만족도에 관한 연구

임덕환 한국청각언어재활학회 2012 Audiology and Speech Research Vol.8 No.1

Successful auditory rehabilitation programs involve satisfaction measures for clients. The final outcomes may eventually lead to either satisfaction or dissatisfaction. It is critical in rehabilitation programs to predict the subjective measures in appropriate time intervals so that individual programs may be modified for better performances. However, reliable quantitative protocols serving these purposes have been limited in number and practice. In this study, an effective model of estimating satisfaction measures was developed to describe future outcomes of the programs. This modeling process was based on stochastic Markov process where the previous state was related to the next state. In this model, transient probabilities were computed to address individual states in session numbers of a rehabilitation program. The model was applied in a sample group of old adults (N = 12) wearing hearing aids with similar unaided scores of PTA and WRS to observe the estimated properties of satisfaction. The results showed that the asymptotic value of satisfaction was reached under the given condition as the session number was increased. With these data, the prospective outcomes of the program can be monitored for its overall efficacy. The protocol may also contribute to optimizing evaluation and management to facilitate the rehabilitative process.

아파트 공동주택의 소음분쟁에 대한 법률적 분석

임덕환 한국청각언어재활학회 2010 Audiology and Speech Research Vol.6 No.2

Noise disturbances in residential apartments have been one of the growing issues in recent domestic court cases with the ever increasing number of apartment housing. In this study, the legal systems of both domestic and foreign laws were analyzed on the issue and related exemplary domestic court cases were reviewed. In conclusion, the legal aspects of the current judgment system seemed to be based mainly on the theory of illegal acts in civil law. In managing this environmental issue, the government agency also provided the buffered stage leading to arrangement, mediation, or arbitration before the main court procedure. However, there should be improved practical ways to fulfill the technological guidelines on the determination of noise level in disputed cases along with the verification of the guidelines themselves. The future legal system should overcome the current limitation of the legal basis on illegal acts in civil law and should include multidimensional approaches reflecting appropriate legal policies of the authorities and general perception of the society on the issue.

청각인지에 영향을 미치는 교실음향 변수

임덕환 한국청각언어재활학회 2009 Audiology and Speech Research Vol.5 No.1

It has been known that the effects of acoustics parameters of the room on auditory perception were diverse and even critical in some population groups. Public regulation on classroom acoustics has emerged as one of the concerned issues in educating children and the hearing impaired. The purpose of this study was to review the effects of acoustic parameters, such as reverberation time, acoustic insulation, and acoustic absorption, on speech perception in classroom. An exemplary regulation suggested from ANSI (S12.60, 2002) and related assessment tools were analyzed as well with special reference to adapting appropriate guidelines to domestic environments. In conclusion, it seemed now imperative that the related authority should establish effective acoustic requirements and guidelines for schools since ample data showed that the young children with hearing problem were prone to be at risk of learning opportunities. The reviewed parameters were dominant physical variables of speech intelligibility in classroom acoustics and this analysis might help to resolve issues on implementing acoustic regulation on classroom acoustics in the future.

청각기능검사를 위한 다기능 디지털 전산 자극음 합성 시스템

임덕환 대한이비인후과학회 1999 대한이비인후과학회지 두경부외과학 Vol.42 No.7

정상 한국성인의 모국어 단음절 청각 숫자 기억 처리에 관한 연구

임덕환,문지연 한국청각언어재활학회 2011 Audiology and Speech Research Vol.7 No.2

Digit spans were frequently used as a potential tool for evaluating central auditory signal processing such as auditory memory and learning. The basic detailed data, however, were not available for Korean digit span sets. In this study, Korean monosyllable digit spans were examined in normal hearing adults. The stimuli were synthesized in 1 to 10 Korean digit spans of male and female voices. They were randomly presented through the closed acoustic system for 20 subjects (10 males and 10 females). The corresponding responses were recorded and analyzed on the custom-made computerized workstation. In this result, no statistically significant differences were observed in terms of the lateralization (left/right) and the gender of the subjects and speakers (p > .01). The average performance point of 50% was determined at the index value of about 8 in this Korean digit span study. In conclusion, the data exhibited the similar trends as those from digit span experiments with other languages. Further language specific outcomes can be analyzed with the addition of the related digit intervals and controlled acoustical features. This procedure may also contribute to clinical applications on screening and probing memory-related central processing disorders.

잔향시간이 양이를 사용한 한국어 단음절 인지에 미치는 영향

임덕환 한국음향학회 2021 韓國音響學會誌 Vol.40 No.6

실내에서 소음과 함께 존재하는 잔향시간은 어음인지에 영향을 미친다. 그 정도는 청취 조건이나 사용된언어의 특성에 따라서 그 내용이 다를 수 있다. 본 연구에서는 양이 청취 조건에서 잔향시간이 정상 성인 10인의 표준화된 한국어 단음절 변별력에 미치는 효과를 확인하고자 하였다. 양이 청취효과는 diotic(양이 소음간 동일 위상) 조건과dichotic(양이 소음 간 위상차 존재, π) 조건에서 신호대잡음비를 0 dB로 고정하였다(55 dB HL). 잔향시간 효과를 관찰할 수 있는 3.4 s에서 대상의 단음절 변별력인 Word Recognition Score(WRS)점수를 분석하였다. 결과에서dichotic인 경우에는 단측 청취 결과와 비교하여 유의한 변별력 개선이 보였고(p < 0.05), diotic 조건에서는 단측청취와 유의한 차이를 관찰할 수 없었다. 이러한 결과는 잔향시간을 고려한 여러 소음 음향 환경 분석에 참고가 될 수 있을것으로 판단된다. Reverberation Time (RT) with noise levels can affect speech recognition ability in a listening environment. The degree of influence may depend on reverberation times and modes of binaural hearing. In this study, Korean monosyllabic Word Recognition Scores (WRS) were investigated in 10 young normal hearing subjects under binaural conditions. The RT of 3.4 s and signal to noise ratio of 0 dB were used at 55 dB HL for diotic (noise with the same phase) and dichotic (noise with the fixed phase difference, π) conditions. The improvement in WRS was noted in dichotic hearing (p < 0.05) while the similar trend was not observed in diotic hearing. This data may be useful in analyzing psychoacoustic effects of RTs under noisy conditions.

Biotinylated dextran amine (BDA)를 응용한 금화조 song control 시스템의 간접 청각 입력 경로 분석

임덕환 한국청각언어재활학회 2011 Audiology and Speech Research Vol.7 No.1

The zebra finch (Poephila guttata) has been known to have the nuclei of the song control system which contain highly selective neurons. They respond exclusively to a bird’s own song. The mechanism for this song selectivity is critical in understanding song-related behaviors such as vocal learning and memory. Though important advancement has been continued in this area, the exact nature of functional and anatomical correlates are still under investigation. In this retrospective study, local areas of field L, especially L2, were traced with a new modified application protocol of biotinylated dextran amine (BDA) to examine how general auditory inputs were anatomically connected to the song control system (HVc, hyperstriatum ventral pars caudalis) in the forebrain of the adult male zebra finch. The injection of BDA tracer was controlled to be confined within the L2 area (N=3) and connections were traced in both retrograde and anterograde directions. The data confirmed that Field L2 area provided the input to the shelf area of the HVc instead of direct connections to the HVc proper. Thus, song selectivity appeared to be achieved indirectly with the addition of at least one more processing stage (shelf) between L2 and HVc.

청각장애 영유아의 보청기 적합에 사용되는 탐지역치와 불쾌역치 변수에 대한 고찰과 보완

임덕환 한국장애인재활협회 2010 재활복지 Vol.14 No.2

출생 직후부터 시행되는 조기 선별검사를 통해서 난청의 확인이 시도되는 국내의 현 시점에서 조기 중재의 중요성 때문에 이제는 대략 생후 3개월 정도부터 보청기가 처방되는 추세이다. 이렇게 나이가 어린 청각장애 영유아의 보청기를 조정하는 적합(fitting) 과정에는 근본적으로 해결해야하는 문제가 있다. 영유아의 나이가 어리거나 중복장애를 갖는 경우에는 흔히 사용되는 주관적인 행동반응에 근거한 청각검사로는 보청기 착용 전이나 착용 후 또는 조정 후의 주파수별 탐지역치와 불쾌역치와 같은 보청기 적합을 위한 기본 변수의 확인에 한계가 있다. 주관적 검사방법이 불가한 경우에 보청기 착용하기 전에는 청각 자극에 대한 전기생리학적 반응을 이용하여 여러 객관적인 청각 검사방법들이 사용되게 된다. 그러나 이러한 객관적인 검사를 보청기를 착용한 상태에서도 시행하여 탐지역치와 불쾌역치를 확인하고 있는 경우를 국내에서 임상적으로 보기가 어렵다. 주된 이유는 보청기를 착용한 상태에서도 확인할 수 있는 청성뇌간유발반응(ABR)이나 등골근반사역치(ART)에 대한 실질적인 지침과 이해가 필요하기 때문으로 생각된다. 현재 이러한 보청기를 착용한 경우에는 보청기 적합을 위한 전산프로그램 속에 내재되어 있는 평균적인 값에 근거한 보청기 적합공식을 사용하거나, 주요 변수에 대한 통계적 가정에 근거한 물리적 측정을 하거나, 안전을 위해 매우 보수적인 조절로 대체하는 경우가 대부분이다. 본 연구에서는 국내의 청각장애자 영유아 중에서 이러한 기본 정보를 확인하기 어려운 경우들을 고찰하여 보고, 보청기를 착용한 상태에서의 주파수별 탐지역치와 불쾌역치를 객관적으로 확인하는 방법을 보완하여 보청기 착용 전과 착용 후 그리고 조정전과 조정후의 모든 경우에 주파수별 기본 탐지역치와 불쾌역치를 확인하는 개선된 지침을 제안하였다. It has been well known that the early intervention is important in auditory rehabilitation of infants with hearing loss. As of today, new digital hearing aids were commonly prescribed, when appropriate, for hearing-impaired infants as young as about 3 months of age with the help of newborn hearing screening programs. This trend, however, led to tremendous requirements on fitting hearing aids due to extreme difficulties in both aided and unaided subjective behavioral measurements of basic fitting parameters such as detection thresholds and uncomfortable loudness levels (UCL). Under the circumstances, auditory brainstem responses (ABR) and acoustic reflex thresholds (ART) were adopted as alternative objective measurements of detection thresholds and UCLs only under unaided conditions. Clinically, neither detection thresholds in aided ABR nor were UCLs in aided ART were confirmed since no direct calibrated connections were provided between transducers and hearing aids. In this study, issues on fitting basic parameters of hearing aids were reviewed for difficult infant cases and improved practical objective methods were suggested to verify frequency detection thresholds and UCLs under aided and unaided conditions. In conclusion, aided levels of detection thresholds and UCLs should be included as well in the routine evaluation battery for difficult pediatric cases under this new modified scheme since safe and correct acoustic amplifications were even more critical in young infants with hearing loss.