Effects of extraordinary tonal sounds observed from approaching aircraft on the evaluation of accumulated sound exposure around theairport

摘要

It is recently reported that extraordinary peculiar tonal sound is sometimes heard during theapproach of some new low-noise aircraft, although the mechanism of the sound generationremains unknown. This paper describes result of an investigation of such unusual sound fromaircraft observed under the approaching flight path at Narita International Airport. As a resultof the investigation, the rate of unusual sound generation was about 2%, although such soundmight sometimes cause a prominence of sound pressure level 10dB or higher than that withoutsuch sound. It was also found that the generation of such sound is the most frequent in the caseof approaching of state-of-the-art aircraft with twin-engine such as B-777. Finally, the paperdiscusses the effects of such sound on the evaluation of accumulated sound exposure as well ason the automated monitoring of aircraft noise around the airport.