Title: AN EXPERIMENTAL MICROHONE ANTENNA ARRAY FOR MEASURING AIRCRAFT NOISE
Abstract: In recent years, aircraft noise pollution has become a public issue. Governments try to set tight limits for this aircraft noise pollution. In accordance with the Dutch government, a new integrated measurement and calculation system for aircraft noise is being developed in the Netherlands. The immision levels of the aircraft have to be measured at specific locations and these measurements form the basis for the noise maintenance. An existing Noise Monitoring System (NOMOS) is based on single omnidirectional microphones. These measurements are strongly influenced by other noise sources like trains, cars, and reflections and by wind turbulence. Applying array technology in measuring aircraft noise improves the SNR significantly. Being able to decompose the noise for their angles of incidence gives the opportunity to measure the noise from specific angles, and therefore omitting unwanted noises from other directions and reducing windnoise. From an earlier investigation, a sparse line array was preferred, consisting of 15 microphones, measuring the octave bands of 125 Hz to 2000 Hz. This frequency range is sufficient to measure the A-weighted immision levels of representative aircraft. Computer simulations showed good results and for verification this array was built and tested. Because of the size and robustness, very small microphones, also used in hearing aid applications, were used. Outdoor measurements, next to official NOMOS measurement units for comparison, were performed. Temporary results show a SNR improvement of 5 to 10 dB, due to minimization of the influence by unwanted noise sources. The SNR improvement is dependent on the angular spacing of the sources. Further research is performed on improving the angular resolution. (A) For the covering abstract see ITRD E113232.
Publication Year: 2001
Publication Date: 2001-01-01
Language: en
Type: article
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Cited By Count: 1
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