• Journal of Oral Medicine and Pain
• /
• v.35 no.1
• /
• pp.49-59
• /
• 2010

The purpose of this study was to investigate short-term masticatory muscle reactions in response to simulated noise and music sound. Hypothesis of this study was that loud noise would cause increased stiffness and decreased elasticity of the masticatory muscles compared to low level of noise or identical sound level of music. Fifteen male volunteers were recruited for the study. The sound levels of noise and music used here were 60 dB and 100 dB. The experiment comprised 4 sessions, Session 1 with 100 dB of noise for the 1st day of experiment: Session 2 with 100 dB of music for the $2^{nd}$ day: Session 3 with 60 dB of noise for the $3^{rd}$ day: Session 4 with 60 dB of music for the $4^{th}$ day. Stiffness and elasticity on the anterior temporalis and superficial masseter muscles were measured with tactile sensor before and 2, 4 and 6 minutes after exposure of sound. The study indicated that, in short-term exposure of sound, there was no significant difference between noise and music at both 60 and 100 dB of sound level, but that there were partially significant differences between 60 and 100 dB of sound level regardless of sound type. This suggest that high level of sounds like 100 dB used in this study, in spite of short term exposure of several minutes, would lead to masticatory muscle contraction, especially in the masseter muscles.

• Science of Emotion and Sensibility
• /
• v.6 no.4
• /
• pp.41-49
• /
• 2003

To inspect how the different sensitivities in BAS(or BIS) modulate on the HRV pattern stimulated by positive or negative affective sound, we measured the electrocardiogram(ECG) of 25 students(male : 14), consisted of 4 groups depending on the BAS(or BIS) sensitivity, during listening meditation music or being exposed to noise. The power spectral density(PSD) of HRV was derived from the ECG, and the power of HRV was calculated for 3 major frequency ranges(low frequency[LF], medium frequency[MF], and high frequency[HF]). We found that the index of MF/(LF+HF), during listening music, was higher significantly in the individuals with a low BIS but high BAS than in the individuals with a low sensitivity in both BIS and BAS. Especially in the former group, there was a tendency that the index was higher during listening music than during being exposed to noise. For individuals with a high BIS, regardless of the BAS sensitivity, the difference of this index values was not significant. From these results we suggest that individuals with a low BIS but high BAS are more sensitive to positive affective stimuli than other groups, and the index of MF/(LF+HF) is applicable to evaluate positive and negative affects.

• Korean Journal of Clinical Laboratory Science
• /
• v.38 no.3
• /
• pp.224-230
• /
• 2006

Up to now, there have been rare clinical studies on leaders and aerobics athletes. To get the useful data for protecting from auditory disorder, we selected 15 female aerobics leaders (experimental group) and 15 females (control group) unexperienced in aerobics and a without neurological and octolaryngological disorder. The average age was $34.87{\pm}8.80$ (experimental group) and $34.07{\pm}8.45$ (control group) years, and the average career of an aerobics leader (experimental group) was $8.33{\pm}4.73$ years. We measured the auditory evoked potential (AEP) of the two groups treated with 70, 75 and 85 dB intensity from January 2006 to May 2006 and analyzed the absolute latency (AL) and interpeak latency (IPL) by the SPSS/pc+ 12.0 program. In the comparison of the AL between the experimental group and the control group according to intensity, both ears treated with 70 and 75 dB had a significant difference (p<0.05) in the I, III, V wave and in the I, V wave respectively, and the experimental group treated with 85 dB showed a difference in the I, III, V wave (left ear) and in the I wave (right ear) respectively. The IPL of the two groups treated with various intensities had no prolongation. In the comparison of the AL between the experimental group and the control group according to ages, the experimental group in their 20s treated with 70 dB showed a significant difference (p<0.05) in the V wave (left ear) and in the I, III, V wave (right ear), and the experimental group in their 20s treated with 75 dB in the I, III wave (left ear) and in I, III, V wave (right ear), and experimental group in their 20s treated with 85 dB in the V wave (left ear) and in the III, V wave (right ear). The experimental group in their 30s treated with 70 dB had a significant difference (p<0.05) only in the V wave (right ear). Only in the IPL of subjects in their 20s treated with 85 dB, III-V and I-V of both ears was extended. In the comparison of the AL and IPL according to career, there was no significant difference between the two groups. From this results, we concluded that the lower sound intensity (70 dB) showed a more significant difference in the experimental group than the control group. We concluded that the leader of aerobics exposed to louder sounds than normal people are affected by auditory neurological and octolaryngological disorders. So we think that the leaders of aerobics need to control the noise level for protecting themselves against a disease.

• Phonetics and Speech Sciences
• /
• v.15 no.1
• /
• pp.25-34
• /
• 2023

This study examined the utility of the acoustic features of vowels as cues for the place of articulation of Korean nasal consonants. In the acoustic analysis, spectral and temporal parameters were measured at the 25%, 50%, and 75% time points in the vowels neighboring nasal consonants in samples extracted from a spontaneous Korean speech corpus. Using these measurements, linear discriminant analyses were performed and classification accuracies for the nasal place of articulation were estimated. The analyses were applied separately for vowels following and preceding a nasal consonant to compare the effects of progressive and regressive coarticulation in terms of place of articulation. The classification accuracies ranged between approximately 50% and 60%, implying that acoustic measurements of vowel intervals alone are not sufficient to predict or classify the place of articulation of adjacent nasal consonants. However, given that these results were obtained for measurements at the temporal midpoint of vowels, where they are expected to be the least influenced by coarticulation, the present results also suggest the potential of utilizing acoustic measurements of vowels to improve the recognition accuracy of nasal place. Moreover, the classification accuracy for nasal place was higher for vowels preceding the nasal sounds, suggesting the possibility of higher anticipatory coarticulation reflecting the nasal place.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.10 no.4
• /
• pp.227-235
• /
• 1977

The noise pressure scattered underwater on account of the engine revolution of a pole and liner, Kwan-Ak-San(G. T. 234.96), was measured at the locations of Lat. $34^{\circ}47'N$, Long. $128^{\circ}53'E$ on the 16th of August 1976 and Lat. $34^{\circ}27'N$, Long. $128^{\circ}23'E$ on the 28th of July, 1977. The noise pressure passed through each observation point (Nos. 1 to 5), which was established at every 10m distance at circumference of outside hull was recorded when the vessel was cruising and drifted. In case of drifting, the revolution of engine was fixed at 600 r. p. m. and the noise was recorded at every 10 m distance apart from observation point No. 3 in both horizontal and vertical directions with $90^{\circ}$ toward the stern-bow line. In case of cruising, the engine was kept in a full speed at 700 r.p.m. and the sounds passed through underwater in 1 m depth were also recorded while the vessel moved back and forth. The noise pressure was analyzed with sound level meter (Bruel & Kjar 2205, measuring range 37-140 dB) at the anechoic chamber in the Institute of Marine Science, National Fisheries University of Busan. The frequency and sound waves of the noise were analyzed in the Laboratory of Navigation Instrument. From the results, the noise pressure was closely related to the engine revolution shelving that the noise pressure marked 100 dB when .400 r. p. m. and increase of 100 r. p. m. resulted in 1 dB increase in noise pressure and the maximum appeared at 600 r. p. m. (Fig.5). When the engine revolution was fixed at 700 r. p. m., the noise pressures passed through each observation point (Nos. 1 to 5) placed at circumference of out side hull were 75,78,76,74 and 68 dB, the highest at No.2, in case of keeping under way while 75,76,77,70 and 67 dB, the highest at No.3 in case of drifting respectively (Fig.5). When the vessel plyed 1,400 m distance at 700 r.p.m., the noise pressure were 67 dB at the point 0 m, 64 dB at 600m and 56 dB at 1,400m on forward while 72 at 0 m, 66 at 600 m and 57 dB at 1,400 m on backward respectively indicating the Doppler effects 5 dB at 0 m and 3 dB at 200 m(Fig.6). The noise pressures passed through the points apart 1,10,20,30,40 and 50 m depth underwater from the observation point No.7 (horizontal distance 20 m from the point No.3) were 68,75,62,59,55 and 51 dB respectively as the vessel was being drifted maintaining the engine revolution at 600 r. p. m. (Fig. 8-B) whereas the noise pressures at the observation points Nos.6,7,8,9 and 10 of 10 m depth underwater were 64,75,55,58,58 and 52 dB respectively(Fig.8-A).