Effects of noise from aircraft in flight

One of the aims of this paper is a presentation of the results concerning the frequency characters, noise contours, NNI contours and PWL (A) of aircraft in flight obtained from the measured values of sound level in the vicinity of Osaka International Airport. Another aim is a suggestion of some remedies for the noise-problem around the airport.The noise from aircraft in flight in the area in question was found the most intense in the slender zone right beneath the take-off flight path. In this zone the effects of noise upon the inhabitants are observed unbearable to them, judging from the NNI values there.The first radical step to settle this noise problem is, of course, the removal of the airport itself. For the present, however; in order to reduce the effects of the noise these measures should be taken: (1) putting in force the noise certification by establi shing a noise criterion which will be settled below the present noise level of aircraft within the technological possibility, (2) shifting the present flight paths to improved ones, (3) controlling the number of flights in the airport.