Necessity of sound source identification is widely recognized in noise measurement, such as the Noise Evaluation Manual issued by the Ministry of the Environment where sounds not targeted for the measurement are to be omitted from the calculation of noise indices. Although it cannot be free from uncertainty, since sound source identification is conducted by means of subjective judgment, it has not been closely examined. In this study, 30 subjects participated in the experiment where the sound sources of 9 sonic environments recorded in Arashiyama, Kyoto were presented through headphones and made judgments on the sound sources. The standard uncertainty of the identification was less than 2 percent when the target sound is higher by 10 dB than the background sound level (LA95) in the sonic environment.
The attenuation of sound due to atmospheric absorption depends strongly on environmental temperature and humidity. For that reason, it varies in response to changing meteorological conditions on a variety of time scale. Moreover, large variations occur according to the place in actual meteorological conditions. The authors have calculated the attenuation coefficients for atmospheric absorption at altitudes up to about 5,000 m from meteorological data obtained at eight aerological observatories in Japan during a year. Results show that the temporal fluctuations of the attenuation coefficients tend to increase with increasing the altitude, though the variability characteristics of the attenuation coefficients during the year depend strongly upon both the sonic frequency and the place. The effects of atmospheric absorption on aircraft noise propagation were examined using the calculated attenuation coefficients at various heights. As a result of this study, it has been found that the A-weighted sound pressure levels and sound spectra of aircraft noise vary strongly because of the seasonal changes in atmospheric absorption which depends on actual meteorological conditions.
Gamelan is the traditional ensemble music which has mainly progressed in Indonesia and Malaysia. Bali in Indonesia is known as an island of entertainments with gods. For Balinese people, Gamelan is a part of life and is indispensable to soundscape for daily life. There are various Gamelan and instruments on rites and dances in Bali of Indonesia. The keyboard instruments for most of Balinese Gamelan are tuned to get the interference beats emitted by beating a pair of instruments. In this paper, the beat frequencies for the keyboard instruments of two sets of Gamelan Gender Wayang and Gamelan Angklung whose scale is slendro retuned by two tuners are also compared and considered.