指示騒音計による蛙と蝉の群集発音活動量の測定 : 発音活動と環境の関係

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Sound-level meter was applied for the first time in measuring quantitatively the vocal activities of the communities of frogs and cicadas incorporated with the conventional hearing method which had been used in ecological investigations. By the above new method, the diurnal periodicities of these activities and their relations to environments were studied. Surrounding factors such as air temperature, relative humidity, water temperature, intensity of illumination and heat radiation were measured. To obtain the vocal activity quantitatively, sound level was measured as follows: microphone was usually placed at a distance from the community and songs picked up exceptionally near the microphone were eliminated from the data; measuring time was taken long enough to cover the trends ups and downs of activity of the community; it was ascertained that the distance between the microphone and the community did not vary widely; and the microphone was held in constant orientation with the community in consideration of the directivity characteristics. By using the sound-level meter it was found as follows: (1) In Terpnosia vacua diurnal vocal activity (average sound level) corresponded to illumination; (2) In summer cicadas (Platypleura Kaempferi, Cryptotympana japonensis and Graptopsaltria nigrofuscata) the average level of each species was maintained nearly constant in the daytime and their vocal activities appeared to be in saturation; (3) In Hyla arborea japonica the increase of activity at dusk corresponded to the decrease of illumination; (4) With these frogs seasonal ups and downs of activity was observed but there was no apparent relation with the age of the moon; (5) With same frog taken into consideration the type of variation of activity throughout a night was not apparently affected by the moon-light; (6) This frog sang throughout the night, while Rana rugosa sang in the former half of the night and Rana limnocharis in the latter half. So they manifested respectively their specific activities, and the types of time variation of average level in their activities were also characteristic. Relative activities of the three species of frogs were varied by their habitats and season and as the result of their sum-mation there appeared various type of nocturnal vocalization. It was assumed that the vocal activities of these animals were chiefly affected by the intensity of illumination.
社団法人日本音響学会の論文
1956-03-30

指示騒音計による蛙と蝉の群集発音活動量の測定 : 発音活動と環境の関係

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