• 말소리와 음성과학
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• 제3권4호
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• pp.45-53
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• 2011

Flemming and Johnson (2007) claim that there is a fundamental distinction between the mid central vowel [ə] and the high central vowel [?] in that [ə] occurs in an unstressed word-final position while [?] appears elsewhere. Compared to English counterparts, Korean [ə] and [?] are full vowels and they have phonemic contrast. The purpose of this paper is to explore the acoustic quality of two English reduced vowels produced by Korean learners and native speakers of English in terms of their two formant frequencies. Sixteen Korean learners of English and six native speakers of English produced four types of English words and two types of Korean words with different phonological and morphological patterns. The results show that Korean learners of English produced the two reduced vowels of English and their Korean counterparts differently in Korean and English words.

• 말소리와 음성과학
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• 제2권3호
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• pp.3-10
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• 2010

The proposal that a sound change is occurring in Korean stops was evidenced in this study through identification experiments on Korean stops. Perceptual weight of acoustic correlates to Korean stop manner contrast [VOT (Voice Onset Time), H1-H2 (amplitude difference between the first and second harmonics), and F0 (Fundamental frequency)] was examined with re-synthesized /$t^ha$/, /ta/, and /$t^*a$/ syllables for younger and older Seoul speakers of Korean. For the identification of the aspirated and lenis stops, F0 cue weight relative to VOT was greater for the younger listeners than the older listeners. For H1-H2 cue weight, the two listener groups were more or less the same. These findings were parallel to the production differences found in the earlier work of the author. Combined with production differences, these perception differences between younger and older generations of Seoul speakers suggested that there are generational differences in the phonetic targets of Korean aspirated and lenis stops and such differences are realized in the perception of the stops.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.638-643
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• 2007

With development of high display quality of TV and Monitor, personal audio system is arising great interest. In this study, we applied a method to make a good bright zone around the user and dark zone to other region by maximizing the ratio of sound energy between the bright and dark zone. We have attempted to use a line speaker array system to localize the sound in our listening zone. It depends on the size of the zone and array parameters, for example, array size, speaker spacing, wave length of sound.

• 전기학회논문지
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• 제59권12호
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• pp.2349-2351
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• 2010

Photo Acoustic Tomography (PAT) is a hybrid imaging modality which combines high contrast of optical imaging and spatial resolution of ultrasound imaging, thus it is suitable to image biological tissue noninvasively. Laser-induced photoacoustic signals were measured from a sample by means of an unfocused ultrasound transducer, then PAT image was reconstructed based on a universal back-projection algorithm. To evaluate the feasibility of our system, phantom test was performed, consequently, the PAT images obtained using our system showed highly analogous shape and volume with those of the phantom. This result demonstrated that our system can provide a powerful tool for imaging the substructure of biological tissue in non-invasive manner.

• 대한음성학회:학술대회논문집
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• 대한음성학회 1996년도 10월 학술대회지
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• pp.208-213
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• 1996

This paper reports a preliminary investigation on the time course of intersyllabic coarticulation in Standard Chinese. In this investigation, around 3800 phonetically compact C1V1-C2V2 type disyllabic structures 3re employed to observe the acoustic effect of coarticulation in general, and about 400 disyllabic words are designed as the materials to examine: (1) How the articulators move from one syllable to the next？ (2) What is the extent to which the syllables overlapped？ And (3) In what sense, the syllables are produced in parallel; and in what sense, they are in sequence？ For the convenience of description, we just take the offset transition of V1 end the onset transition of C2 os the rough representations for anticipatory and carryover effect respectively, durational measurements are made correspondingly. To evaluate the possible influence on the behavior of gestural overlap from stress contrast and constituent difference of the syllables, analysis of variance are counducted as well. Based on this study, Some impressions about general nature of coarticulation behined the intersyllabic gesture overlapping in this language are discussed.

• 말소리와 음성과학
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• 제6권4호
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• pp.47-52
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• 2014

This study investigated how the degree of attention modulates English learners' perception of Korean stop contrasts. The contributions of VOT and F0 in perceiving Korean stops were examined while availability of attentional resources was manipulated using a dual-task paradigm. Results demonstrated the attentional modulation in the use of VOT, but not in F0: under less attention, the contribution of VOT to the perception of aspirated stops decreased, whereas that of lenis stops increased, which suggests more native-like performance. This implies that the role of attention in perceiving non-native contrasts might differ depending on how equivalent the acoustic and perceptual cues are between L1 and target L2 contrasts.

• 음성과학
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• 제9권4호
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• pp.201-214
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• 2002

In the Japanese language, there is a phonological contrast between not only initial stops, but also non initial in voiced and voiceless sounds. But in the Korean language, voiced sounds do not appear in the initial. Due to this, pronunciation of voiced sounds in the initial will be difficult for Korean. Through this research, I analyzed the minimal pairs by voiced/voiceless sounds of Japanese and Korean, and perception experiment in which Japanese listened to Korean speakers' pronunciations. Japanese pronunciations showed distinct acoustic differences between voiced and voiceless stops, especially in VOT. The duration of vowels after voiced stops was longer than that of voiceless ones. Vowel pitches after voiceless stops were higher. On the other hands, Korean showed three patterns of voiced sounds. There were-VOT values as native speakers, +VOT, and nasal formant tended to occur before prenasalized stops. Koreans pronounced voiceless sounds in strong aspirated, unaspirated, or tense sounds. Finally, Japanese judged sounds with not only -VOT values and prenasalized, but also with +VOT values as voiced. This suggests that we may not consider VOT values as the unique feature of voicing, and that such other phonetic characteristics as the following vowel lengthening should be included here.

• 음성과학
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• 제13권2호
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• pp.107-120
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• 2006

The main purpose of this study is to investigate whether Korean learners can use the vowel duration cue to distinguish voicing contrasts in word-final consonants in English. Given that the Korean group's performance on the auditory task was much better than their performance on the identification task or on the production task, we conclude that the AX discrimination task makes contact with a different layer of perception. In particular, the AX discrimination task can be done at the auditory or phonetic level, where differences in vowel length are still encoded in the representation. In contrast, the identification and production tasks are probing the mental representation of vowel length and voicing. It was also founded that Korean speakers stored neither vowel length nor voicing in memorized representations and did not internalize the lengthening of the preceding vowel as a rule to differentiate the voicing contrasts of final consonants, even though they were able to detect the acoustic differences in vowel duration provided that they were tested in an appropriate task.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1998년도 추계학술대회
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• pp.219-220
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• 1998

Although a single-element synthetic aperture system can produce high-resolution beam profile, it is not a highly practical system because of its low signal to noise ratio against conventional system's. A multi-element synthetic aperture processing has been proposed with defocusing in this paper. A multi element subaperture defocused to emulate a single element spatial response with high acoustic power. The results have higher signal to noise and better contrast resolution than conventional synthetic aperture method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.47-50
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• 1988

In this paper, Rayleigh wave velocity has been measured by detecting the backscattered signal generating near the Rayleigh critical angle in the elastic medium. The rotating system has been made for the measurment of Rayleigh angle. It has been shown that the measured results has been good agreement with the theoretical value. The method of non-destructive evaluation using backscattering signal has been presented and the internal of IC sample has been displayed acoustic image with good contrast.