• The Journal of the Acoustical Society of Korea
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• v.37 no.5
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• pp.276-283
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• 2018

The purpose of the study is to identify a sound generating organ that has a major influence on the central frequency of the cicadas with the Helmholtz resonator structure for the first time. The sound of cicadas Cryptotympana atrata and Hyalessa fuscata were recorded and analyzed, then the motion of the tymbals was analyzed with a high-speed camera to compare the relationship between the frequency of sound and the motion of the tymbals. As a result, there was little difference in the frequency distribution of calling song and scream for two species. The tymbals of C. atrata oscillated in three vibration modes, while those of H. fuscata oscillated in one mode. There was no difference in the frequency of both tymbals of both cicadas, and three vibration modes of C. atrata generated sound with different frequency bands. The frequency band of tymbals and the central frequency band of calling song were very similar. In conclusion, it is presumed that the frequency of the cicadas with the Helmholtz resonator structure was determined by mode frequency of the tymbals than resonance condition of the abdomen.

• The Journal of the Acoustical Society of Korea
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• v.29 no.2
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• pp.125-132
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• 2010

Since the ancient times, animals that can imitate the voices of human beings have been considered extremely special. There are very few such animals, and the parrot is an example of them. For a long time, there had been no reported case of a rooster being able to mimic the voice of a human being, but talking roosters were recently found in Korea and the Kyrgyz Republic, generating much talk. In this study, the vocal characteristics of such roosters were examined, and their pronunciation-related statistics and actual sound sources were analyzed. The analysis results showed that even though the roostets cannot converse with people, they can imitate the human voice, uttering the words "An-dwae," and "A-ni-ya" in Korean, which mean "No" in English, when someone tries to catch their wings. A similar situation 'occurred in the Kyrgyzstan. The results of the listening survey on these sounds made by the roosters showed that most people recognized the words uttered by the roosters and that nobody thought that the words sounded like "cock-a-doodle-doo." It can be said that such roosters can make the sounds of the human voice because of their innate vocal organ and characteristics, which are significantly different from those of the general roosters. Their vocal organ and characteristics cause the sounds that they make to change in their vocal cords due to their high tension when humans try to catch them.

• The Journal of the Acoustical Society of Korea
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• v.24 no.7
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• pp.379-386
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• 2005

Among various kinds of hearing aids which have been developed so far. the conventional air conduction hearing aids have some problems such as the acoustic distortion, an howling effect due to acoustic feedback. Another type of hearing aid. the cochlear implant system can be applied to the profound imparied person. However. it shows the disadvantage that there is no possibility of recovery of the acoustic organ such as ossicle. On the other hand. the implantable middle ear heaving device directly vibratos the ossicular chain and has better sound qualify. good cosmetics for appearance. and wide frequency responses so that it can overcome the defects or the conventional hearing aids. In this paper, a mathematical modeling and a momentum equation derivation of the DET has been performed. For the optimization of the structure dimension generating maximal vibrating force of the DET. the computer simulation using a finite element analysis (FEA) software has been performed. Also. the vibrating transducer has been designed to make the frequency characteristics or the transducer be similar to those of the normal middle ear. Through the experimental results, the measured vibration characteristics of the DET has been evaluated to verify the performance for the application to implantable middle ear hearing devices.