• 대한의용생체공학회:의공학회지
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• 제28권2호
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• pp.205-211
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• 2007

A novel envelope extraction algorithm for speech processor of cochlear implants, called adaptation algorithm, was developed which is based on a adaptation effect of the inner hair cell(IHC)/auditory nerve(AN) synapse. We achieved acoustic simulation and hearing experiments with 12 normal hearing persons to compare this adaptation algorithm with existent standard envelope extraction method. The results shows that speech processing strategy using adaptation algorithm showed significant improvements in speech recognition rate under most channel/noise condition, compared to conventional strategy We verified that the proposed adaptation algorithm may yield better speech perception under considerable amount of noise, compared to the conventional speech processing strategy.

• 대한인간공학회지
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• 제24권3호
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• pp.29-34
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• 2005

Little research has been performed regarding auditory icons even though auditory icons have great potentials as a strategy for creating informative, intuitively accessible, and unobtrusive interface. Therefore, this study was conducted to design new auditory icons through the iconic mapping for ten most frequently used mobile phone menus, and to show the usability of auditory icons. Two most familiar auditory sounds for each menu were collected and compared to the current button-pressing sound. The results show that the newly designed auditory icons had shorter recognition times, better satisfaction than the current icons. In other words, auditory icons could be an effective interface to provide a redundant feedback along with visual feedbacks in navigating mobile devices.

• 음성과학
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• 제9권1호
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• pp.7-16
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• 2002

This study tested normal hearing adults' auditory perception of rhythm and intonation patterns, with low-frequency speech energy. The results showed that the narrow-band low-frequency zones of 125, 250, or 500 Hz provided the same important rhythm and intonation cues as did the wide-band condition. This suggested that an auditory training strategy that uses low-frequency filters would be effective for structuring or re-structuring the perception of rhythm and intonation patterns. These filters force the client to focus on these patterns, because the speech intelligibility is drastically reduced. This strategy can be used with both normal-hearing and hearing impaired children and adults with poor listening skills, and possibly poor speech intelligibility.

• 음성과학
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• 제11권3호
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• pp.201-211
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• 2004

This paper introduces a development of an electrical stimulator for auditory stimulation. The electrical stimulator is useful in neurotological diagnosis, audiological evaluation, candidate selection for cochlear implantation, optimal device selection and decision making of MAP strategy for severe-to-profound hearing impaired persons. The development was based on sound parameters of auditory brainstem responses and auditory electrophysiological characteristic such as effective firing of auditory nerve and recording evoked potentials during refractory period of neuron. Besides pulse parameter could adjustable by programming for more varied electrical stimulation evoked response audiometry. Using the electrical stimulator, electrical square pulse was applied to promontory, and electrically evoked auditory brainstem response and electrically middle latency response were successfully recorded in cats.

• 대한의용생체공학회:의공학회지
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• 제28권2호
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• pp.271-279
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• 2007

We suggest a novel method for the evaluation of cochlear implant (CI) speech processing strategy based on neural spike train decoding. From formant trajectories of input speech and auditory nerve responses responding to the electrical pulse trains generated from a specific CI speech processing strategy, optimal linear decoding filter was obtained, and used to estimate formant trajectory of incoming speech. Performance of a specific strategy is evaluated by comparing true and estimated formant trajectories. We compared a newly-developed strategy rooted from a closer mimicking of auditory periphery using nonlinear time-varying filter, with a conventional linear-filter-based strategy. It was shown that the formant trajectories could be estimated more exactly in the case of the nonlinear time-varying strategy. The superiority was more prominent when background noise level is high, and the spectral characteristic of the background noise was close to that of speech signals. This confirms the superiority observed from other evaluation methods, such as acoustic simulation and spectral analysis.

• 대한의용생체공학회:의공학회지
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• 제28권5호
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• pp.694-702
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• 2007

The adaptation effect originating from the chemical synapse between auditory nerve and inner hair cell gives advantage in accurate representation of temporal cues of incoming speech such as speech onset. Thus it is expected that the modification of conventional speech processing strategies of cochlear implant(CI) by incorporating the adaptation effect will result in considerable improvement of speech perception performance such as consonant perception score. Our purpose in this paper was to evaluate our new CI speech processing strategy incorporating the adaptation effect by the observation of auditory nerve responses. By classifying the presence or absence of speech from the auditory nerve responses, i. e. spike trains, we could quantitatively compare speech onset detection performances of conventional and improved strategies. We could verify the effectiveness of the adaptation effect in improving the speech onset representation characteristics.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1995년도 제12회 음성통신 및 신호처리 워크샵 논문집 (SCAS 12권 1호)
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• pp.184-187
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• 1995

This paper proposes an algorithm for machine recognition of phonemes in continuous speech. The proposed algorithm is static strategy neural network. The algorithm uses, at the stage of training neuron, features such as PARCOR coefficient and auditory-like perceptual liner prediction . These features are extracted from speech samples selected by a sliding 25.6msec windows with s sliding gap being 3 msec long, then interleaved and summed up to 7 sets of parmeters covering 171 msec worth of speech for use of neural inputs. Perfomances are compared when either PARCOR or auditory-like PLP is included in the feture set.

• 대한의용생체공학회:의공학회지
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• 제34권2호
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• pp.47-54
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• 2013

Electrical stimulation is delivered to auditory nerve (AN) through the electrodes in cochlear implant system. Neurogram is a spectrogram that includes information of neural response to electrical stimulation. We hypothesized that the similarity between a neurogram and an input-sound spectrogram could show how well a cochlear implant system works. In this study, we evaluated electrical stimulus configuration of CIS strategy using the computational model. The computational model includes stochastic property and anatomical features of cat auditory nerve fiber. To evaluate similarity between a neurogram and an input-sound spectrogram, we calculated Structural Similarity Index (SSIM). The results show that the dynamic range and the stimulation rate per channel influenced SSIM. Finally, we suggested the optimal configuration within the given stimulus CIS. We expect that the results and the evaluating procedure could be employed to improve the performance of a cochlear implant system.

• 디지털융복합연구
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• 제13권12호
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• pp.259-268
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• 2015

청각처리장애는 정상 청력을 가졌음에도 불구하고 청각신경계에서 청각 정보를 처리하는 과정의 문제로 자신이 들은 소리를 이해하지 못한다. 본 연구는 최근 문헌들이 제시하는 청각처리장애의 중재 방법을 조사하여 청각 처리장애를 가진 아동을 위한 중재 안내도를 마련하고자 하였다. 청각처리장애를 가진 아동은 진단의 구체적 결함에 따라 Buffalo 모델과 Bellis/Ferre 모델의 유형으로 분류되고 결함을 치료하기 위한 문제중심 중재 전략과 결함의 영향을 관리하는 전반적 중재 전략이 결정된다. 그리고 문제중심 중재 전략은 두 모델의 유형별 특징에 따라 맞춤 전략으로 구성되고, 전반적 중재 전략은 보상 전략, 청능훈련, 환경수정 등이 추천된다. 이러한 중재가 진행되기 위해서는 다학문적 팀에 의해 아동의 청각 기능을 향상시킬 수 있는 다양한 중재 방법들을 선정하고 집중적이고 지속적으로 제공하여야 한다. 청각처리장애의 중재 안내도는 청각처리장애 확인, 중재, 재평가, 수정된 중재 단계로 구성되었다. 이 안내도를 통해 청각처리장애가 의심되거나 청각처리장애를 진단 받은 아동의 어려움을 줄이기 위하여 관련 임상가와 교사들이 적절한 중재 방법과 절차를 찾을 수 있도록 돕고자 하였다.

• 대한의용생체공학회:의공학회지
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• 제29권1호
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• pp.25-31
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• 2008

It is well known that temporal information, i.e speech onset, about input speech can be represented to the response nerve signal of auditory nerve better depending on the adaptation effect occurred in the auditory nerve synapse. In addition, the performance of a speech processor of cochlear implant can be improved by the adaptation effect. In this paper, we observed the emphasis characteristic of speech onset in the recently proposed adaptation algorithm, analyzed the characteristic of performance change according to the variation of parameters and compared with transient emphasis spectral maxima (TESM) is the previous typical strategy. When observing false peaks which are generated everywhere except speech onset, in the case of the proposed model, the false peak were generated much less than in the case of the TESM and it is more distinguishable under noise.