• Korean Journal of Audiology
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• v.25 no.2
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• pp.80-88
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• 2021

Background and Objectives: Non-linear frequency compression (NLFC) technology compresses and shifts higher frequencies into a lower frequency area that has better residual hearing. Because consonants are uttered in the high-frequency area, NLFC could provide better speech understanding. The aim of this study was to investigate the clinical effectiveness of NLFC technology on the perception of speech and music in patients with high-frequency hearing loss. Subjects and Methods: Twelve participants with high-frequency hearing loss were tested in a counter-balanced order, and had two weeks of daily experience with NLFC set on/off prior to testing. Performance was repeatedly evaluated with consonant tests in quiet and noise environments, speech perception in noise, music perception and acceptableness of sound quality rating tasks. Additionally, two questionnaires (the Abbreviated Profile of Hearing Aid Benefit and the Korean version of the International Outcome Inventory-Hearing Aids) were administered. Results: Consonant and speech perception improved with hearing aids (NLFC on/off conditions), but there was no significant difference between NLFC on and off states. Music perception performances revealed no notable difference among unaided and NLFC on and off states. The benefits and satisfaction ratings between NLFC on and off conditions were also not significantly different, based on questionnaires, however great individual variability preferences were noted. Conclusions: Speech perception as well as music perception both in quiet and noise environments was similar between NLFC on and off states, indicating that real world benefits from NLFC technology may be limited in Korean adult hearing aid users.

• Journal of Audiology & Otology
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• v.25 no.2
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• pp.80-88
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• 2021

Background and Objectives: Non-linear frequency compression (NLFC) technology compresses and shifts higher frequencies into a lower frequency area that has better residual hearing. Because consonants are uttered in the high-frequency area, NLFC could provide better speech understanding. The aim of this study was to investigate the clinical effectiveness of NLFC technology on the perception of speech and music in patients with high-frequency hearing loss. Subjects and Methods: Twelve participants with high-frequency hearing loss were tested in a counter-balanced order, and had two weeks of daily experience with NLFC set on/off prior to testing. Performance was repeatedly evaluated with consonant tests in quiet and noise environments, speech perception in noise, music perception and acceptableness of sound quality rating tasks. Additionally, two questionnaires (the Abbreviated Profile of Hearing Aid Benefit and the Korean version of the International Outcome Inventory-Hearing Aids) were administered. Results: Consonant and speech perception improved with hearing aids (NLFC on/off conditions), but there was no significant difference between NLFC on and off states. Music perception performances revealed no notable difference among unaided and NLFC on and off states. The benefits and satisfaction ratings between NLFC on and off conditions were also not significantly different, based on questionnaires, however great individual variability preferences were noted. Conclusions: Speech perception as well as music perception both in quiet and noise environments was similar between NLFC on and off states, indicating that real world benefits from NLFC technology may be limited in Korean adult hearing aid users.

• Proceedings of the Acoustical Society of Korea Conference
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• 1994.06c
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• pp.199-204
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• 1994

In this paper, we researched abut CELP speech coding algorithm using efficlent pseudo-stochastic block codes, adaptive-codebook and improved fixed-gain codebook. The pseudo-stochastic block codes refer to stochastically populated block codes in which the adjacent codewords in an innovation codebook are non-independent. The adaptive-codebook was made with previous prediction speech data by storage-shift register. This CELP coding algorithm enables the coding of toll quality speech at bit rates from 4.8kbits/s to 9.6 kbits/s. This algorithm was realized TMS320C30 microprocessor in realtime.

• English Language & Literature Teaching
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• v.13 no.3
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• pp.77-97
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• 2007

To compare data on the speech act of requests from two different methods, a study was conducted in which both native and non-native speakers of English participated as subjects, and data were collected by means of actual e-mail writing and DCT (discourse completion test). The analysis of requests from the two different data-gathering methods showed that despite some similarities, considerable differences existed between e-mail and DCT requests in several important aspects of requests such as amount of talk, directness level, downgraders and supportive moves which play an important role in making a given request sound less imposing and more polite. Also it was shown that requests of non-native speakers differed considerably from requests of native speakers in terms of the four aspects of requests across type of data-gathering methods. Based on the findings, some suggestions were made for both further research and L2 classrooms.

• Proceedings of the KSPS conference
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• 2005.04a
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• pp.99-102
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• 2005

Research efforts have been made for out-of-vocabulary word rejection to improve the confidence of speech recognition systems. However, little attention has been paid to non-recognition sentence rejection. According to the appearance of pronunciation correction systems using speech recognition technology, it is needed to reject non-recognition sentences to provide users with more accurate and robust results. In this paper, we introduce standard phoneme based sentence rejection system with no need of special filler models. Instead we used word spotting ratio to determine whether input sentences would be accepted or rejected. Experimental results show that we can achieve comparable performance using only standard phoneme based recognition network in terms of the average of FRR and FAR.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.9
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• pp.165-170
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• 2014

Speech enhancement techniques that remove surrounding noise are stressed to preprocessor of speech recognition. Among the various speech enhancement techniques, Codebook-based Speech Enhancement (CBSE) operates efficiently in non-stationary noise environments. But, CBSE has some problems that inaccurate gains can be estimated if mismatch occur between input noisy signal and trained speech/noise codevectors. In this paper, the Normalized Weighting Factor (NWF) is calculated by long-term noise estimation algorithm based on Signal-to-Noise Ratio, compensated to the conventional inaccurate gains. The proposed CBSE shows better performance than conventional CBSE.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.1
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• pp.169-174
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• 2010

This paper explains end-point detection method for better speech recognition rates. The proposed method determines speech and non-speech region with the entropy and the harmonic detection of speech. The end-point detection using entropy on the speech spectral energy has good performance at the high SNR(SNR 15dB) environments. At the low SNR environment(SNR 0dB), however, the threshold level of speech and noise varies, so the precise end-point detection is difficult. Therefore, this paper introduces the end-point detection methods which uses speech spectral entropy and harmonics. Experiment shows better performance than the conventional entropy methods.

• Phonetics and Speech Sciences
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• v.1 no.3
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• pp.109-115
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• 2009

Many isolated word recognition systems may generate non-similar words for recognition candidates because they use only acoustic information. In this paper, we investigate several techniques which can exclude non-similar words from N-best candidate words by applying Levenstein distance measure. At first, word distance method based on phone and syllable distances are considered. These methods use just Levenstein distance on phones or double Levenstein distance algorithm on syllables of candidates. Next, word similarity approaches are presented that they use characters' position information of word candidates. Each character's position is labeled to inserted, deleted, and correct position after alignment between source and target string. The word similarities are obtained from characters' positional probabilities which mean the frequency ratio of the same characters' observations on the position. From experimental results, we can find that the proposed methods are effective for removing non-similar words without loss of system performance from the N-best recognition candidates of the systems.

• Speech Sciences
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• v.13 no.3
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• pp.97-105
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• 2006

The objective of this study was to analyze the acoustic patterns of Japanese /t/ produced by 40 Korean speakers in order to find an effective method of teaching it to Koreans. The experimental data consisted of 400 /t/ phonemes in word initial or non-initial positions of 10 words. Informants were in their twenties and raised in Daejeon and the surrounding area. Results showed that there were distinctive trends in duration and intensity of the major and non-major groups productions. Both groups pronounced the phoneme longer than the native speakers with more open mouths but with less loudness. The formant analysis showed that F1 values of the Japanese /t/ pronounced by Japanese major group were lower than those of the non-major. Its F2 values by the major group were higher than those of the non-major, which would suggest that the Koreans produced the tongue blade in more frontal position than the native speakers.

• Speech Sciences
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• v.11 no.4
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• pp.151-161
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• 2004

The characteristics of generative naming ability between fluent aphasiacs and non-fluent aphasics were investigated for 10 fluent aphasics (6 Wernicke's and 4 conduction type) and 10 non-fluent aphasics (6 Broca's and 4 transcortical motor type). Subjects were given 2 types of generative naming task and asked to generate lists of words to categorical ('animal', 'things at a supermarket') and phonetic ('ㄱ', 'ㅇ', 'ㅅ') cues. The total numbers of correct and incorrect response and error type ratios were calculated. The results of the present study were as follows: (1) Fluent aphasics had higher generative naming scores than non-fluent aphasics. (2) A remarkable dissociation between performance on categorical and phonetic cue in both aphasic groups was observed. Both aphasic groups produced a large number of responses in the categorical cue. (3) There was no significant group-difference in the error type. (4) Any correlation between generative naming and confrontation naming in K - WAB was not found.