• Speech Sciences
• /
• v.1
• /
• pp.55-81
• /
• 1997

In the present paper, V-to-V coarticulation in Korean VCV sequences is discussed, focusing on links between consonantal production and degree of V-to-V coarticulation. Temporal and spatial differences between three types of Korean alveolar stops (lax /t/. aspirated /$t^h$/ and thense /t'/) are examined from VCV sequences involving all possible combinations of three Korean unrounded vowels /a, i,/ based on spectrographic and electrographic data(two male speakers and one female speaker and one female speaker respectively). Closure duration and voice onset time (VOT) were measured from acoustic data. 'Total duration', which is defined as the sum of the closure duration and the VOT, was also calculated in order to see the temporal distance between two vowels in a VCV sequence. Differences in lingual-palatal contact pattern at the maximum contact (MC) point between the three types of stop were observed from EPG data. V-to-V coarticulation was investigated by measuring the offset or onset of the second formant (F2) of the target vowels from spectrograms. Two different dimensions of articulation, temporal and spatial, seem to playa role in determining the degree of V-to-V coarticulation. The degree of V-to-V anticipatory coarticulation is influenced by the spatial characteristics of the intervening consonant while the degree of carryover coarticulation is influenced by the temporal characteristics of the consonant.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
• /
• v.23 no.1
• /
• pp.33-42
• /
• 2012

Background and Objectives : Dysarthria refers to speech disorder that causes difficulties in speech communication due to paralysis, muscle weakening, and incoordination of speech muscle mechanism caused by damaged central or peripheral nerve system. Pitch, strength and speed are influenced by dysarthria during detonation due to difficulties in muscle control. As evaluation items, alternate motion rate and diadochokinesis have been commonly used, and articulation is also an important evaluation items. The purpose of this study is to find acoustic characteristics on sound production of dysarthria patients. Materials and Methods : Research subjects have been selected as 20 dysarthria patients and 20 subjects for control group, and voice sample was composed of bilabial, alveolar sound, and velar sound in diadochokinetic rate, while consonant articulation test was composed of bilabial plosive, alveolar plosive, velar plosive. Analysis items were composed of 1) speaking rate, energy, articulation time of diadochokinesis, 2) voice onset time (VOT), total duration (TD), vowel duration (VD), hold of plosives. Results and Conclusions : The number of diadochokinetic rate of dysarthria was smaller than control group. Both control group and dysarthria group was highly presented in the order of /t/>/p/>/k/. Minimum energy range per cycle during diadochokinetic rate of dysarthria group was smaller than control group, and presented statistical significance in /p/, /k/, /ptk/. Maximum energy range was larger than control group, and presented statistical significance in /t/, /ptk/. Articulation time, gap, total articulation time during diadochokinetic rate of dysarthria group was longer than control group and presented statistical significance. The articulation time was presented in both control group and dysarthria group in the order of /k/>/t/>/p/, while Gap was presented in the order of /p/>/t/>/k/ for control group and /p/>/k/>/t/ for dysarthria group. VOT, TD, VD regarding plosives of dysarthria group were longer than control group. Hold showed large deviation compared to control group that had appeared due to declined larynx and articulation organ motility.

• MALSORI
• /
• no.48
• /
• pp.1-17
• /
• 2003

Among the types of dysarthria, spastic and flaccid types are the most prominent manifestations. The objectives of the present research are (1) to discover the phonetic contrasts that differentiate spastic dysarthria from flaccid dysarthria, (2) to analyze the degrees of predictability of each phonetic contrast for intelligibility in spastic and flaccid dysarthrias and to compare them. The 'phonemic contrast word intelligibility pairs' for dysarthric speakers were tested and proved to be useful for clinical assessment of and research on dysarthria. In the group of spastic type, it showed that initial fricative vs. affricate and front vs. back vowel contrasts are transmitted relatively less effectively than flaccid type. In the group of flaccid type, initial glottal vs null contrast is transmitted less effectively than spastic type. The overall intelligibility of spastic dysarthria was predicted by multiple regression analysis with 88% accuracy by three phonetic contrasts(initial fricative vs. affricate; front vs. back vowels; initial consonant correlates). And the intelligibility of flaccid dysarthria was predicted by two phonetic contrasts(initial nasal vs. stop, front vs. back vowels) with 60% accuracy.

• Speech Sciences
• /
• v.9 no.4
• /
• pp.131-142
• /
• 2002

Place assimilation in Korean has been argued to reflect the consonantal strength hierarchy in which velar is stronger than labial which is in turn stronger than coronal. The strength relationship has been manifested in two ways in literature. One is through phonological representation as shown in Iverson and Lee (1994). The other is through perceptual salience ranking as suggested by Jun (1995). The goal of this study is to examine the perceptual salience of placed consonants through an identification experiment. The experiment conducted in this study reveals four facts. First, place identification of a prevocalic consonant is higher than that of a postvocalic one. Second, place identification of a stop in coda is more confusable than that of a nasal counterpart in Korean contrary to other previous studies. Third, velar is most confusable in place identification in contrast to Jun (1995) and Hume et al. (1999). Finally, place perception of consonants can vary depending on adjacent vocalic context. These results suggest that perceptual salience is one of the possibly several factors affecting a phonological process.

• The Journal of the Acoustical Society of Korea
• /
• v.23 no.2
• /
• pp.162-172
• /
• 2004

This study investigates the following three things through a production experiment and acoustic analysis: 1) relationship between speech rate and the segment duration in Korean, 2) relationship between speech rate and spectral characteristics of vowels, i. e. undershoot, and 3) correlation between the vowel duration and undershoot. The results showed that the faster the speech rate nab, the shorter the duration of syllables and segments was. A few speakers were affected by speech rate in the durational ratios between closure and aspiration in a stop and between Towel and consonant in a syllable. Closure duration and vowel duration were more affected compared to aspiration and consonant duration, respectively. Speakers showed some differences in the extent to which speech rate affected vowel undershoot, implying that speakers used different production mechanisms for spectral characteristics of vowels: Some speakers speeded up movement of articulatory organs according to speech rate increase while some kept it constant regardless of speech rate change.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
• /
• v.17 no.2
• /
• pp.98-102
• /
• 2006

Background and Objectives : Voice onset time(VOT) is defined as the time interval from oral release of a stop consonant to the onset of glottal pulsing in the following vowel. VOT is a temporal characteristics of stop consonants that reflects the complex timing of glottal articulation relative to supraglottal articulation. Stop consonants are characterized by creation of a pressure difference across a complete occlusion in the vocal tract, followed by a sudden release 'burst' due to opening that occlusion. The objects of this study is to evaluate a usefulness of voice onset time in the assessment of voice disorderd patients. Subjects : Subjects were 20 adults with normal voice and with benign laryngeal disorders. Subjects with voice disorders represented the following vocal pathologies : vocal polyp, vocal nodule, Reinke's edema and unilateral vocal fold paralysis(UVFP). Control subjects were matched for age (21-40 yews old) and sex(male) with the voice disorders subjects and had normal vocal qualities with no history of voice disorders. Methods : Each voice-disordered and matched control subject read the test passages containing three types of Korean bilabial consonants. VOT measures were made for the initial $/p/p^h/\;and\;/p'/$. VOT was measured using acoustic waveform or wide band spectrogram. Results : For each voiceless stop consonants, there was a significant difference in VOT between the voice disordered and normal subjects. The mean VOTs of the lax stops in UVFP was significantly shorter than those of control subjects in the UVFP. The mean VOTs of the aspirated stops in the vocal polyp and nodule were longer than those of control subjects, but not significant. The mean VOTs of the glottalized in voice disordered groups were longer than those of control subjects, and significant statistically in the UVFP. Conclusions : VOT may be a clinically useful acoustic parameter in the assessment of voice disordered patients, especially in the unilateral vocal fold paralysis.

• Phonetics and Speech Sciences
• /
• v.3 no.3
• /
• pp.27-33
• /
• 2011

This paper explores two articulatory characteristics of inter-consonantal coordination observed in lingual-lingual (/kt/, /ks/) and labial-lingual (/pt/) sequences. Using electromagnetic articulometry (EMMA), temporal aspects of the lip movement and lingual movement (of the tongue tip and the tongue dorsum) were examined. Three sequences (/ks/, /kt/, /pt/) were investigated in two respects: gestural overlap in C1C2 and formation duration of coronals in C2 (/t/ or /s/). Results are summarized as follows. First, in a sequence of two stop consonants gestural overlap did not vary with order contrast or a low-level motor constraint on lingual articulators. Gestural overlap between two stop consonants was similar in both /kt/ (lingual-lingual; back-to-front) and /pt/ (labial-lingual; front-to-back). Second, gestural overlap was not simply constrained by place of articulation. Two coronals (/s/ and /t/) shared the same articulator, the tongue tip, but they showed a distinctive gestural overlap pattern with respect to /k/ in C1 (/ks/ (less overlap) < /kt/ (more overlap)). Third, temporal duration of the tongue tip gesture varied as a function of manner of articulation of the target segment in C2 (/ks/ (shorter) < /kt/ (longer)) as well as a function of place of articulation of the segmental context in C1 (/pt/ (shorter) < /kt/ (longer)). There are several implications associated with the results from Korean non-assimilating contexts. First, Korean can be better explained in the way of its language-specific gestural pattern; gestural overlap in Korean is not simply attributed to order contrast (front-to-back vs. back-to-front) or a physiological motor constraint on lingual articulators (lingual-lingual vs. nonlingual-lingual). Taking all factors into consideration, inter-gestural coordination is influenced not only by C1 (place of articulation) but also C2 (manner of articulation). Second, the jaw articulator could have been a factor behind a distinctive gestural overlap pattern in different C1C2 sequences (/ks/ (less overlap) vs. /kt/ and /pt/ (more overlap)). A language-specific gestural pattern occurred with reference to a physiological motor constraint on the jaw articulator.

• Speech Sciences
• /
• v.11 no.1
• /
• pp.87-103
• /
• 2004

This study investigates Korean listeners' perception of the English stop epenthesis between the sonorant and fricative segments. Specifically this study investigates 1) how often English epenthetic stops are perceived by native Korean listeners, given the fact that Korean does not allow consonant clusters in codas; and 2) whether perception of the epenthetic stops, which are optional phonetic variations, not phonemes, could be improved without any explicit training. 120 English non-words with a mono-syllable structure of CVC1C2, where C1=/m, n, $\eta$, 1/, and C2=/s, $\theta$, $\int$/, were given to two groups of native Korean listeners, and they were asked to detect the target stops such as [p], [t], and [k]. The number of their responses were computed to determine how often listeners succeed in recovering the string of segments produced by the native English speaker. The results of the present study show that English epenthetic stops are poorly identified by native Korean listeners with low English proficiency, even in the case where stimuli with strong acoustic cues are provided with, but perception of epenthetic stops is closely related with listeners' English proficiency, showing the possibility of the improvement of perception. It further shows that perception of epenthetic stops shows asymmetry between coronal and non-coronal consonants.

• Proceedings of the Acoustical Society of Korea Conference
• /
• 1994.06a
• /
• pp.1033-1038
• /
• 1994

This paper describes recognition results using the modified Learning Vector Quantization (MLVQ2) method which we proposed previously. At first, we investigated the property of duration of 29 Korean consonants and found that the variances of th duration were extremely big comparing to other languages. We carried out preliminary recognition experiments for three stop consonants P, T and K. From the recognition results, we defined the optimum conditions for the learning. Then we applied the MLVQ2 method to the recognition of Korean consonants. The training was carried out using the phoneme samples in the 611 word vocabulary uttered by 2 male speakers, where each of the speakers uttered two repetitions. The recognition experiment was carried out for the phoneme samples in two repetitions of the 611 word vocabulary uttered by another male speaker. The recognition scores for the twelve plosives were 68.2% for the test samples. The recofnition scores for the 29 Korean consonants were 64.8% for the test samples.

• Phonetics and Speech Sciences
• /
• v.6 no.2
• /
• pp.141-151
• /
• 2014

This study reports anti-hierarchical initial-syllable lengthening of an utterance-internal phrase in Korean. That is, the phrase-initial syllable (e.g., /a/ of "apa-do" or /ma/ of "mapa-do") starting with a voiced phoneme (i.e., vowels or voiced consonants) manifests itself as significantly longer when it is preceded by another phrase without a pause than when it leads an utterance or follows a pause utterance-internally. The phenomenon was examined with regard to two other factors: (1) tempo and (2) tenseness of the consonant (/p, $p^{\prime}$, $p^h$/) following the target syllable /a/. First, the effect of tempo on initial lengthening was not significant. Apart from the statistical significance, however, a tendency was observed, i.e., the slower the tempo is, the greater the lengthening. By contrast, the faster the tempo is, the higher the ratio (%) of lengthening. Second, contrary to our expectations, initial-syllable lengthening was even greater before tense stops /$p^{\prime}$, $p^h$/ than before lax stop /p/ regardless of tempo, and it was remarkable when it comes to the ratio (%), which means that initial lengthening is free of the pre-consonantal vowel shortening effect. Final-syllable lengthening is a pre-boundary marker, while the initial-syllable lengthening is regarded as a post-boundary marker of a phrase.