• Speech Sciences
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• v.10 no.2
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• pp.207-221
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• 2003

Phonetic voicing does not support the phonological distinction of voiced/voiceless in English stops. The present study is aimed at defining the nature of voicing of English voiced stops. A review of the literature reveals that the voicing is position-conditioned and its length is notably inconsistent relative to the closure duration. No consistent relationships are found between vocal fold adduction and glottal pulsing in initial position. Stress reduced the voicing, etc. The hypothesis for experiments was: (1) active voicing: stress generates longer (stronger) voicing during the closure duration of a voiced stop; (2) passive voicing: stress induces shorter (weaker) voicing during the closure. Instead the voiced stop becomes more voiced when the preceding vowel (syllable) is stressed. The literature review and the results of two experiments comparing English and Slovakian suggested that the voicing of English voiced stops is passive (i.e., a coarticulation of glottal pulsing for adjacent vowels-syllables) and should be distinguished from active voicing in some other languages.

• Phonetics and Speech Sciences
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• v.8 no.3
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• pp.21-29
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• 2016

This study examined how native Korean speakers realize the acoustic characteristics of /d, t/ flaps in American English. Fourteen subjects, who had lived in foreign countries for less than one year, read words containing the alveolar stops in flapping environments. /d/ (91%) became flaps more frequently than /t/ (42%). The closure durations for /d/ flaps were significantly longer than /t/ flaps, and the durations of the preceding vowels were not significantly different between /d/ and /t/ flaps. Female learners demonstrated a higher percentage of /t/ flapping than their male counterparts. Differences in flap patterns were observed among individual learners.

• Speech Sciences
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• v.13 no.2
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• pp.47-58
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• 2006

People tend to control their speech rate to help those with listening problems such as hearing impaired people. The aim of this study was to investigate effects of speech rate on the sentence perception by 10 adults with cochlear implantation. The sample speech included 42 sentences at normal, slow, and very slow speed focusing on the overall duration, vowel or pause duration. The subjects listened to the speech and wrote down what they heard. Each correct syllable of the content words in the sentence was counted to obtain the score. Partial points were given to the incomplete syllables. Results of this study were as follows: 1. The changes of speech rate had some influence on the sentence perception score by the cochlear implanted people. 2. In slow pause condition, the controlled speech rate had a positive effect on the perception score.

• Cross-Cultural Studies
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• v.24
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• pp.112-119
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• 2011

This study presents experiments which examined the role of amplitude and fundamental frequency (f0) in the phonetic perception of short versus long stop length contrasts in Japanese (e.g., [t] vs. [tt]). Stop length contrasts are normally characterized by differences in the duration of stop closures. However, closure duration can be unreliable as a perceptual cue when one considers variability in the rate at which people speak. Acoustically, the amplitude and f0 of the vowel following stop consonants are known to covary with the length distinction of stops in Japanese. Given this fact, the current study examined amplitude and f0 as potential secondary cues to the distinction. The results indicate that even though both amplitude and f0 are robust correlates, Japanese listeners do not use these cues in categorizing short versus long stops.

• Phonetics and Speech Sciences
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• v.3 no.1
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• pp.135-143
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• 2011

This study evaluated the respiratory capacity of spastic cerebral palsy children who were grouped by GMFCS (Gross Motor Function Classification System) levels and identified the acoustic characteristics of three different types of Korean stops (stop consonants) which are needed for the temporal coordination of larynx and supra-larynx, in these children. Thirty-two children with dysarthria due to spastic cerebral palsy were divided into two subgroups: 14 children classified at GMFCS levels I~III were placed in Group 1 and 18 classified at GMFCS levels IV~V were placed in Group 11, and 18 children with normal speech were selected and placed in the control group. /a/ pronged phonation (sustained vowel /a/) and nine Korean VCV syllables were used. Examined acoustic characteristics were maximum phonation time (MPT) and closure duration and aspiration duration. The results were as follows: 1) The MPTs of the cerebral palsy (CP) groups, both Group I and Group II, were significantly shorter than those of the normal group. 2) The closure durations of the two CP groups were longer than those of the normal group for all 9 target syllables. 3) The aspiration durations of the two CP groups were longer than those of the normal group. 4) The closure duration of the normal and CP Group I was significantly different among tense, aspirated, and lax. However, the CP Group II was different from normal. 5) The aspiration duration of the normal and CP Group I was significantly different among aspirated, tense, and lax. However, the CP Group II was different from normal. 6) The place of articulation influenced less than the manner of articulation on closure and aspiration duration.

• Speech Sciences
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• v.8 no.4
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• pp.139-156
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• 2001

Speech intelligibility in patients with complete dentures is an important clinical problem depending on the material used. The objective of this study was to investigate the speech of two edentulous subjects fitted with a complete maxillary prosthesis made of two different palatal materials: chrome-cobalt alloy and acrylic resin. Three patients with complete dentures in the experiment group and ten people in the controls groups participated in the experiment. CSL, Visi-Pitch were used to measure speech characteristics. The test words consisted of a simple vowel /e/, meaningless three syllabic words containing fricative, affricated and stops sounds, and sustained fricative sounds /s/ and /$\int$/. The analysis speech parameters were vowel and lateral formants, VOT, sound durations, sound pressure level and fricative frequency. Data analysis was conducted by a series of paired T-test. The findings like the following: (1) Vowel formant one of patients with complete denture is higher than that of the control group (p<0.05), while lateral formant three of patients with complete denture is lower than that of the control group (p<0.0l). (2) Patients with complete denture produced lower speech intelligibility with low fricative frequency (/$\int$/) than control group (p<0.0). The speech intelligibility of patients with metal prosthesis was higher than that of those with resin prosthesis (p<0.05). (3) Fricative, lateral and stop sound durations of patients with complete denture were longer than those of the control group (p<0.01 and p<0.05), respectively. Total sound durations of patients with metal prosthesis were similar to that of the control group (p<0.05), while those with resin prosthesis had a shorter duration (p<0.01). This implied that those with metal prosthesis had higher speech intelligibility than those with resin prosthesis. (4) Patients with complete denture had higher sound pressure levels /t/ and /c/ than the control group (p<0.01). However, sound pressure levels for /c/ of patients with metal prosthesis or resin prosthesis was similar to the control group (p<0.05). (5) Patients with complete denture had higher fundamental frequency than the control group (p<0.01).

• Speech Sciences
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• v.15 no.3
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• pp.39-51
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• 2008

Formant measurements are one of the most important factors to objectively test cross-linguistic differences among vowels produced by speakers of any given languages. However, many speech analysis softwares present erroneous estimates and some researchers use them without any verification procedures. The purposes of this paper are to examine formant measurements of complex waves which were synthesized from the average formant values of five Korean vowels using three default methods in Praat and to verify the measured values of the five vowels produced by 20 students using one of the methods. Variances along the time axis are discussed after determining absolute difference sum from the 1/3 vowel duration point. Results show that there were smaller measurement errors by the burg method. Also, greater errors were observed in the sl or lpc methods mostly caused by the inappropriate formant settings. Formant measurement deviations were greater in those vowels produced by the female students than those of the male students, which were mostly attributed to the settings for the vowels /o, u/. Formant settings can best be corrected by changing the number of formants to the number of visible dark bands on the spectrogram. Those results suggest that researchers should check the validity of the estimates from the speech analysis software. Further studies are recommended on the perception test of the original sound with the synthesized sound by the estimated formant values.

• Speech Sciences
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• v.7 no.1
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• pp.187-201
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• 2000

This study was done to investigate the English vowels in relation to the foreign accent. In this study, I also tried to find out the foreign accent of the English diphthong /o/ and front low vowel /${\ae}$/ when Koreans speak English. The reason why I chose these vowels is that these vowels, /o/ and /${\ae}$/, are difficult for Koreans to discern and pronounce. Koreans show a foreign accent in their pronunciation. In order to find out the reason for a Korean foreign accent, experiments were carried out with the help of acoustic instruments. According to the results of the experiment, Koreans showed a foreign accent in their English pronunciation of vowels in relation to their utterance positions. Americans showed a final lengthening effect but Koreans showed a final shortening effect. This means that Koreans showed a foreign accent in the final stressed syllable of a sentence. In addition to this, the duration of two English vowels, /o/ and /${\ae}$/, showed considerably different features between Koreans and Americans. In fact, in the pronunciation of the diphthong /o/, the tongue moves from one position to another. The two articulations of a diphthong can be described as the nucleus plus a glide. However, most Koreans have no idea of this phenomenon and pronounce the diphthongs like two separate monophthongs. This causes a great difference in the lengths of English diphthong /o/ between Koreans and Americans.

• Speech Sciences
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• v.6
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• pp.197-217
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• 1999

In a noisy class, the acoustic-phonetic features of the teacher and the perceptual features of learners are changed comparison with a quiet environment. Acoustical analyses were carried out on a set of French monosyllables consisting of 17 consonants and three vowel /a, e, i/, produced by 1 male speaker talking in quiet and in 50, 60 and 70 dB SPL of masking noise on headphone. The results of the acoustic analyses showed consistent differences in energy and formant center frequency amplitude of consonants and vowels, $F_1$ frequency of vowel and duration of voiceless stops suggesting the increase of vocal effort. The perceptual experiments in which 18 undergraduate female students learning French served as the subjects, were conducted in quiet and in 50, 60 dB of masking noise. The identification scores on consonants were higher in Lombard speech than in normal speech, suggesting that the speaker's vocal effort is useful to overcome the masking effect of noise. And, with increased noise level, the perceptual response to the French consonants given had a tendency to be complex and the subjective reaction score on the noise using the vocabulary representative of 'unpleasant' sensation to be higher. And, in the point of view on the L2(second language) acquisition, the influence of L1 (first language) on L2 examined in the perceptual result supports the interference theory.

• Speech Sciences
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• v.9 no.2
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• pp.25-47
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• 2002

Human language activity in the information society has been developing the communication system between humans and machines. The aim of this study was to analyze dialectal speech in Korea. One hundred Kyungsang and one hundred Cholla informants participated in this study. A CSL and Flexible laryngeal fiberscope were used for analysis of the acoustic and glottal gestures of all the vowels and consonants. Test words were made on the picture cards and letter cards which contained each vowel and each consonant, respectively. The dialogue between the examiner and the informants was recorded in a question and answer manner. The acoustic results of two dialects were as follows: Kyungsang and Cholla informants showed neutralization between /e/ and /$\varepsilon$. However, the apertures of Kyungsang vowels /i, w, u, o/ were higher than those of Cholla vowels. The /wi/ and /$\varepsilon$/ of Kyungsang Diphthong vowels were shown as simple vowels /i/ and /$\varepsilon$/ in Cholla dialect. The VOT of Cholla dilaect was longer than that of Kyungsang dialect. The fricative frequence of Kyurlgsang dialect was about 1000Hz higher than that of Cholla dialect. The glottal widths on fiberscopic images showed that the consonant durations of Kyungsang and Cholla dialects were correlated all together with the acoustic duration on the spectrogram.