• 대한전기학회논문지:시스템및제어부문D
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• 제50권12호
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• pp.590-596
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• 2001

The pre-emphasis is an essential process for speech signal processing. Widely used two methods are the typical method using a fixed value near unity and te optimal method using the autocorrelation ratio of the signal. This study proposes a new pre-emphasis method using the short-term energy difference of speech signal, which can effectively compensate the glottal source characteristics and lip radiation characteristics. Using the proposed pre-emphasis, speech analysis, such as spectrum estimation, formant detection, is performed and the results are compared with those of the conventional two pre-emphasis methods. The speech analysis with 5 single vowels showed that the proposed method enhanced the spectral shapes and gave nearly constant formant frequencies and could escape the overlapping of adjacent two formants. comparison with FFT spectra had verified the above results and showed the accuracy of the proposed method. The computational complexity of the proposed method reduced to about 50% of the optimal method.

• 음성과학
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• 제14권4호
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• pp.221-232
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• 2007

Topiramate (TPM) is a new antiepileptic drug characterized by a clinical effective reduction in seizure frequency and it represents a useful drug effective in a wide range of epileptic patients. Known side effects are represented by weight loss, hypohidrosis, anorexia, sedation, nephrolithiasis, cognitive complaints and language disorders. This study is to examine acoustic characteristics of patients with TPM. 15 patients were assessed through a Computerized Speech Lab (CSL) applied before the beginning of therapy with TPM and 3 months after medication had been stabilized. Tests had been chosen to assess voice onset time (VOT), total duration (TD), vowel formants, loudness, pitch, speaking rate, and articulation patterns. We compared the data from patients and healthy volunteers. The statistical analysis of the results did not show changes in acoustic tests, except for TD which was increased. The increase of the TD is evaluated as a deterioration of fluency. Our results suggest that patients with TPM did not experience acoustic speech changes except that fluency was declined. Unlike previous studies, the medication of TPM has nothing to do with speech problems in patients with epilepsy.

• 음성과학
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• 제7권1호
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• pp.171-186
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• 2000

The aim of this paper is to investigate the acoustic characteristics of the French vowel [e] and Korean [i] and to seek a way of understanding them from a phonological point of view. These two vowels have similar distributional properties, i.e. they alternate with zero in some contexts. Therefore, in both languages, they are not found when immediately followed by a nucleus with phonetic content and in word-final positions. We firstly compare the two vowels by measuring the actual frequencies of the formants, pitch and energy using CSL. We also consider whether the realisation of the two vowels is affected by the speed of speech sounds. In order to show that realisation of the two vowels in both languages is not arbitrary, rather predicted, we will introduce the notion of proper government, proposed and developed by Kaye (1987, 1990) and Charette (1991).

• 대한음성학회:학술대회논문집
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• 대한음성학회 2003년도 10월 학술대회지
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• pp.55-58
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• 2003

The purpose of this paper was to analyze the effects of nasalization on vowels. Ten males and 7 females produced 5 vowels (/a/, /e/, /i/, /o/, /u/) in conditions: normal and nasalized. In this study we compared normal vowels' formant with nasalized vowels' and examined nasal-formant in the nasalized vowels. The results was as follows: First, there was a significant difference between normal vowels and nasalized in terms of F1 and F2. Second, the nasal formants were observed in nasalized vowels more frequently in females than males. Third, N1 appeared to influence F1 of vowels whereas N2 seemed to have an impact on F2 and/or F3.

• 대한음성학회:학술대회논문집
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• 대한음성학회 2005년도 춘계 학술대회 발표논문집
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• pp.9-13
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• 2005

The aim of this paper is to analyze the vowel lengthening in Korean, whose function is distinctive in the word's level. In this paper, I examined two acoustic parameters : vowel length and formants(F1 and F2) to distinguish or to identify the long vowel and his short correspondant, for exemple, /a:/ and /a/. According to the results of experimental analysis and to the discussion on the vowel length's relation and its influence to Korean phonological system, I considered a vowel lengthening as a prosodeme, so as a prosodic element in Korean phonological system.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1998년도 제15회 음성통신 및 신호처리 워크샵(KSCSP 98 15권1호)
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• pp.159-164
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• 1998

We proposes a new detecting algorithm of DTMF tone for low bit ate vocoder so that we use DTMF tones for signalling inthe digital network. Using DTMF tones for signalling, we could not change the conventional IS-95 protocol and control the mobile phone. We apply the root finding to detection of formants and bandwidth to search whether DTMF tones or voice and moreover to find what's kinds of DTMF tones, for instance 1, 2, 3, ......., #, *, A, B, ...., etc. Consequently, proposed method has a good result which is 0.000944% average error rate. It is satisfied with rcommended error rate in ITU-T($\pm$1.8%).

• 대한음성학회:학술대회논문집
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• 대한음성학회 1996년도 10월 학술대회지
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• pp.367-371
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• 1996

Most Koreans agree that Korean traditional singing voice has a very peculiar sound comparing to Western singing voice. The goal of this paper is to investigate the acoustic characteristics of Korean traditional singing voice called 'Pansori' Materials are analyzed from 3male professional singers and 4 female professional singers. Their singing was compared with their own conversation and other non-singers' conversation. Long term average spectra indicated that all the singers showed a much less spectral tilt than non-singers. The phenomenon was prevailing for professional singers not only in their singing, but also in their conversation. This suggests that it is not the result of a temporary effort but it may involve a certain permanent change in their physiological configuration. (To assess this hypothesis, voice source should be looked at directly. Therefore, in further research, using Rothenberg mask (Rothenberg, 1973) is strongly recommended.) In addition to LTA, individual vowel formants will be studied later.

• 말소리와 음성과학
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• 제2권1호
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• pp.51-58
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• 2010

This study investigates the perception and production of English front vowels focusing on the distinction in /i/ vs /I/ and /$\varepsilon$/ vs /$\ae$/ by sixty-one Korean speakers. The first portion of this study focused on the perceptional discrimination by the subjects of two sets of English vowel contrasts, /i/ vs /I/ and /$\varepsilon$/ vs /$\ae$/. In the second portion of the study, the production of these vowels by the same subjects who had participated in the perceptional discrimination test was examined acoustically and subsequently compared with that of the control group comprised of native English speakers. The major results indicate that: (1) In perception tests, Korean subjects can discriminate between /i/ and /I/ relatively well, while many of them were not able to discriminate between /$\varepsilon$/ and /$\ae$/; (2) the Korean subjects, however, have difficulty producing a distinct version of these front vowels; and, (3) The relationship between the perception and production is not significant. These results were analyzed with the concept of "under-differentiation" and "reinterpretation of distinction," as well as how phonetic differences influenced the production and discrimination of front vowels by Korean speakers.

• 말소리와 음성과학
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• 제6권3호
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• pp.101-108
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• 2014

This study investigates the relation among pitch range differences, speech rate and realization of stress. To identify the realization of the stress, vowel formants and durational differences of stressed and unstressed vowels are measured. The Korean learners were asked to read a textbook passage which includes nine sentences. The major results indicate that: (1) Korean speakers' pitch range is less than 50% of the native speakers; (2) There is a significantly negative relation between high-low pitch range and speech rate; (3) The vowel qualities and durations of the stressed and unstressed vowels are related to the speech rate. But these are not related to the high-low pitch range.

• 대한전자공학회논문지
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• 제26권9호
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• pp.1436-1443
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• 1989

In this paper, we propose a maximum-likelihood estimation(MLE) method to obtain the location and the amplitude of the pulses in MPE( multi-pulse excitation)-LPC speech synthesis using multi-pulses as excitation source. This MLE method computes the value maximizing the likelihood function with respect to unknown parameters(amplitude and position of the pulses) for the observed data sequence. Thus in the case of overlapped pulses, the method is equivalent to Ozawa's crosscorrelation method, resulting in equal amount of computation and sound quality with the cross-correlation method. We show by computer simulation: the multi-pulses obtained by MLE method are(1) pseudo-periodic in pitch in the case of voicde sound, (2) the pulses are random for unvoiced sound, (3) the pulses change from random to periodic in the interval where the original speech signal changes from unvoiced to voiced. Short time power specta of original speech and syunthesized speech obtained by using multi-pulses as excitation source are quite similar to each other at the formants.