• Phonetics and Speech Sciences
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• v.13 no.3
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• pp.53-64
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• 2021

It is known that the voicing contrast for Japanese word-initial stops is primarily realized as differences in the voice onset time (VOT). However, recent studies have reported that voiced stops are more often produced with a positive VOT than with a negative VOT among the younger generation nationwide. It is also known that post-stop F0 is associated with the stop contrast, but the degree of F0 use differs from region to region. This study explores whether the difference in post-stop F0 functions as a perceptual cue to the stop contrast along with VOT. Fifty-five college students who are native listeners from four different regions participated in two or three perception tests. The results show that VOT is a primary cue to the voiced-voiceless distinction of word-initial stops, but that the effect of post-stop F0 on the stop contrast is marginal. The post-stop F0 is involved in perception only when VOT is ambiguous, such that a sound with high F0 is more often perceived as a voiceless stop, but not vice versa. The results of this study indicate that the acoustic parameters associated with the stop contrast are not the same in production and perception, and suggest that other factors such as context, which is not an acoustic characteristic, may also be involved in the stop contrast.

• Phonetics and Speech Sciences
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• v.15 no.1
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• pp.35-45
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• 2023

Tohoku Japanese is known to have voiced stops without pre-voicing in word-initial position, whereas traditional or conservative Japanese has voiced stops with pre-voicing in the same position. One problem with this devoicing of voiced stops is that it affects the distinction between voiced and voiceless stops because their voice onset time (VOT) values overlap. Previous studies have confirmed that Tohoku speakers use post-stop fundamental frequency (F0) as an acoustic cue along with VOT to avoid overlap. However, the role of post-stop F0 as a perceptual cue in this region has barely been investigated. Therefore, this study explored the role of post-stop F0 in stop voicing perception along with VOT. Several perception tests were conducted using resynthesized stimuli, which were manipulated along a VOT continuum orthogonal to an F0 continuum. The results showed no significant regional difference (Tohoku vs. Chubu) for nonsense words (/ta-da/). However, for meaningful words (/pari/ 'Paris' vs. /bari/ 'Bali,' /piza/ 'pizza' vs. /biza/ 'visa'), a significant word effect was found, and it was confirmed that some listeners utilized the post-stop F0 more consistently and steadily than others. Based on these results, we discuss innovative listeners who may lead the change in the perception of stop voicing.

• Speech Sciences
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• v.14 no.4
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• pp.25-39
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• 2007

The present study investigated some perceptual phonetic attributes of two Korean stop types, aspirated and lax, in medial position of an accentual phrase. The intonational pattern across syllables (Jun, 1993) is argued to depend on the type of stop (aspirated vs. lax) only in the initial position of an accentual phrase. In Kang & Dilley (2007), we showed that significant differences between aspirated and lax stops in medial position of an accentual phrase exist in closure duration, voice-onset time, and fundamental frequency (F0) values for post-stop vowels. In the present perception experiment, we investigated whether these phonetic attributes contribute to the perception of these two types of stops: The closure durations and/or F0's of post-stop vowels on accentual-phrase medial words were altered and twenty native Korean speakers then judged these words as beginning with an aspirated or lax stop. Both closure duration and F0 significantly affected judgments of stop identity. These results indicate that a wider range of acoustic cues that distinguish aspirated and lax Korean stops in production also plays a role in perception. To account for these results we suggest some phonetic and phonological models of consonant-tone interactions for Korean.

• Phonetics and Speech Sciences
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• v.8 no.1
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• pp.25-36
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• 2016

Previous studies showed that the voice onset time (VOT) of aspirated and lenis stops has been merged, and post-stop fundamental frequency (F0) has emerged as a primary cue to distinguish the two stops in the younger generation and female speech. The purpose of this study is to demonstrate that VOT merger in aspirated and lenis stops occurs after an F0 difference between the two stops becomes stabilized. In other words, unless post-stop F0, which is a redundant feature, is fully developed, it is hard for VOT merger to happen. Females have got a stable F0 difference in stops earlier than males. Therefore, VOT merger could happen, and as a result, females could take the lead in changing from VOT to F0 in initial stops. This study also shows that speakers who acquired F0 as a primary cue use F0 to the full to distinguish lenis stops from two other stops (aspirated and fortis).

• Speech Sciences
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• v.11 no.4
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• pp.223-232
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• 2004

This study investigated and compared the acoustic characteristics of the Korean stop sound [k'] in three different phonological environments: the tensified lenis stop [k'] as observed in /prek+kaci/, the fortis stop /k'/ as in /pre+k'aci/, and the fortis stop /k'/ following an obstruent as in /prek+k'aci/. The specific research question was whether or not the tensified lenis stop shares all the acoustic features with the other two kinds of fortis stops. The acoustic measures adopted in this study were H1*-H2*, VOT, length of stop closure, and $F_0$. The major findings were that the three stops showed no significant difference in all the acoustic measures except the length of stop closure. The fortis stop /k'/ following an obstruent showed significantly longer duration of stop closure than the other two stops, both of which showed no significant difference. Based on these phonetic results, this study argued that, for the proper phonological description of post-obstruent tensification, the phonological feature [slack vocal folds] of a lenis stop should be changed into [stiff vocal folds, constricted glottis] that the fortis stops should have.

• Speech Sciences
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• v.14 no.3
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• pp.7-19
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• 2007

The present study investigated some phonetic attributes which distinguish two Korean stop types $^-aspirated$ and $lax^-$ in a prosodic position which has previously received little attention, namely medial in an accentual phrase. The intonational pattern across syllables which are initial in an accentual phrase (Jun, 1993) is said to depend on the type of stop (aspirated or lax), while that of syllables which are medial in an accentual phrase are not. In Experiment 1, nine native Korean speakers read sentences with a controlled prosodic pattern in which aspirated or lax stops occurred in accentual phrase-medial position. Acoustic analysis revealed significant differences between aspirated and lax stops in closure duration, voice-onset time, and fundamental frequency (F0) values for post-stop vowels. The results indicate that a wider range of acoustic cues distinguish aspirated and lax Korean stops than previously demonstrated. Phonetic and phonological models of consonant-tone interactions for Korean will need to be revised to account for these results.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.1
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• pp.57-66
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• 2012

The purpose of this study was to evaluate the relation between intentionally induced internal stress and cyclic fatigue failure of ProTaper Universal. ProTaper Universal (Dentsply Maillefer) S1, S2, F1, F2, F3, F4 and F5 (25 mm length) were used in this study. To give the internal stress, the ProTaper Universal were put into the .02 taper Endo-Training-Bloc (Dentsply Maillefer) until auto-stop by torque controlled motor. The rotation speed was 300 rpm and torque value was 1.0 Ncm. ProTaper Universal were grouped by the induced number of internal stress and randomly distributed among one control group and three experimental groups (n=10). The four groups were Stress 0 (control), Stress 1, Stress 2 and Stress 3. These instruments were rotated until separation. For cyclic fatigue measurement, inclined plane was used and time for separation was recorded. It was statistically analyzed using two-way ANOVA and Duncan post-hoc test at 95% confidential level. In all ProTaper Universal, there was statistically significant decrease on time for separation in Stress 3. In F2 and F3, there were statistically significant difference between control group and all experimental groups. And in F4 and F5, Stress 2 and 3 groups showed significantly lower cyclic fatigue resistance from Stress 0 group. In the limitation of this study, cyclic fatigue failure of ProTaper Universal is influenced by accumulated internal stress.

• Journal of Korean Academy of Nursing
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• v.25 no.4
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• pp.653-667
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• 1995

Post - operative wound infections have been a serious problem in nursing care in the operating room and appear to be strongly related to the infection occurring during the performance of operation. The purpose of this study is to identify patterns in duration of surgical hand scrub (SHS), to evaluate the method of SHS and to examine the rate of glove perforation. Subjects for this study include 244 doctors and 169 nurses working in the operative theatre of a hospital in Seoul area. Test samples and related data were collected from this medical facility between April 1, through 15, and July 1, through 5, 1995 by the author and a staff member working in the operating room. For the study, data on the SHS of doctors and nurses were obtained at the time of operation and multiple batches of surgical gloves worn by the operating doctors were collected after each operation. The duration of SHS was measured with a stop watch and the method of SHS was evaluated according to Scoring Hand Scrub Criteria (SHS Criteria) and expressed as SHS scores. For the analysis of the data, t-test was used to compare the differences in the duration and the SHS scores of doctors and nurses, and Pearson's correlation coefficient was used to examine the relationship between the SHS duration and the SHS scores. The results of the study are summarized as follows. 1) The mean time spent in each SHS was 167 seconds in nurses, and 127 seconds in doctors. The data comparing nurses and doctors indicated that there were significant differences in Our ation of SH S between these two groups (t=5.58, p=.000). 2) The mean time spent in the first SHS was 145 seconds and that in the End SHS, 135 seconds, and there was not a significant difference in the duration of the SHS between doctors and nurses (t=1.44, P=.156). 3) The mean time spent in the SHS by OS (Orthopaedic surgery) doctors was 162 seconds, 150 seconds by NS(Neurologic surgery), 121 seconds by GS(General surgery), 94 seconds by OPH(Opthalmology) and DS(Dental surgery), 82 seconds by URO(Urology), 78 seconds by PS(Plastic surgery) and 40 seconds by ENT(Ear, Nose & Throat) These also showed a significant difference in the duration of the SHS among the medical specialities (t=4.8, P=.0001). 4) The average SHS score of the nurses was 15.2, while that of doctors was 13.1. The statistical analysis showed that t-value was 3.66, p was. 000. This indicates that the nurses actually clean their hands more thoroughly than the doctors do. 5) The average SHS score of NS doctors was 15.5, 15.3 for doctors for OPH,14.3 for OS,12.7 for GS, 12.0 for DS, 11.7 for URO, 10.1 for PS, 7.5 for ENT. Comparison of the average SHS scores from 8 specialties showed that there was a significant differences in the patterns of the SHS (F=5.08, P=.000) among medical specialties. 6) It appears that the operating personnel scrub the palms and dorsum of their hand relatively well, however, less thorough the nails and fingers. 7) The more the operating personnel spend their time in hand scrubbing, the more correctly they clean their hands(r=.6427, P<.001). 8) The overall frequencies of perforation in all post-operative gloves tested was 38 out of 389 gloves (10.3%). The perforation rate for PS was 13%, 12.1% for GS,8.8% for 05, and 3.3% for NS.