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Helicopter noise
(Airport Noise Analysis Testing 5)

This time, a helicopter noise is measured at the Air Self Defense Force Komaki base.

Date 27 Feb. 2002 13:00
Weather Cloudy
Temperature 18 degrees centigrade
Humidity 48%
WAVE file: air5.wav (44.1kHz / Stereo / 8sec / 1.34MB)

Digital video camera (Sony Handy-Cam) and external stereo microphones (Audio technica AT9450 one-point stereo condenser microphone) were used. It was recorded on a Mini DV tape with a 16-bit sound. By SONY VAIO DVgate-motion, iLINK connection was made and it reproduced. With the Realtime Analyzer of the RAE, a measurement screen was repeatedly reproduced, and the check of a measurement display was repeated.

Background noise level was 48-50 dB.

A helicopter appeared at the place where we are measuring the takeoff noise of a fighter. Although it is heard quite noisy, they are about 53 dBA according to the sound level meter.

The helicopter passes from left to right. It is far from us. Sound becomes large and small repeatedly.

The 1/3 octave analysis and the peak level display of the helicopter sound is shown.

The time-frequency display of power spectrum.

The real time display of the ACF. Actually, the amplitude becomes large or small.

Running ACF measurement with the integration time of 0.2 seconds was performed for 8 seconds.

Analysis by SA (Sound Analyzer). This is the time course of the relative sound pressure level.

By the screen copy function, graphs of the calculation result can be captured.


January 2002 by M.Sakurai