Development of aircraft tracking camera system for sound power level measurement of aircraft noise

In order to obtain sound power level in a single event of aircraft noise, not only successive series of noise levels in each 1/3 octave band under the flight path, but also distance between the measuring site and the aircraft is needed to measure; the sound power level is estimated by correcting for the amount of sound attenuation due to spherical spreading and air absorption based on the distance to the noise level obtained at the measuring site. As the technique for measuring this distance, we developed an aircraft-tracking camera system by combining a hemispheric camera and motion-tracking. The effectiveness of this system was examined by means of a case study, and it was confirmed that the distance can be reasonably measured just by leaving this system unattended.