Research&Development On Visualization System Of Acoustic Field For The Moving Sound Source

Noise is one of the three significant pollutions in society and the airports noise hasa much more serious impact on the surrounded environment, especially. Not only doesairports noise damage people’s physical and mental health heavily, but also destroy theecology environment of cultivation and farm production at the same time, this leads tosocial problems. Also, if the airports facilities under high decibel value airports noise fora long time, they will be destroyed by mechanical fatigue and will cause economic losewith hidden trouble of flight safety. China’s civilian industry, however, is being in ansoaring period with a speed of14.1%annually. It’s easy to imagine the emerged airportsnoise and the serious impact on the environment followed. So it’s urgent to launch thestudy on regular pattern of airports noise, noise monitoring and noise assessment.The main airports noise source is moving sound source and its acoustic field is thetypical moving sound source radiation. This acoustic field also affected by the layout ofairports, the ecological distribution of surrounded cities and the acoustic properties ofbuilding materials. So to know features of moving sound source radiation and its patternis the premise and foundation for the airports noise monitoring effectively.Use modern measurement technology, distinguish the main sound source precisely,analysis the acoustic filed features is the key manner to solve noise problems producedby moving sound source. The current moving sound source measurement modes arestressed on the typical measurement style like sound pressure method and soundintensity method which can’t reflect the moving sound source objectively. For themoving sound source radiation, the microphone array technology is a new and effectivemeasurement mode which could reflect moving sound source features intuitively ifsupported by the visualization technology, thus, provides a new way of airports noisemeasurement. Another important feature of the moving sound source radiation isDoppler Effect. As the sound signals acquired by the microphone array alwayscombined with Doppler Effect, so need to do Doppler Effect elimination procedure forthe sound signals. In fact, during the reality measurement process, the microphone array could acquire real number signals but can’t get complex number signals immediately forthe Doppler Effect elimination procedure. So for the purpose of continue followingtasks such as the construct of holography functions and the acoustic filed reconstruct,the step of making complex number signals is needed.To express the acoustic field’s status and properties of moving sound source and toverify the usability of acoustic filed visualization software at the same time, trial in theanechoic chamber through build small-size microphone array. Use NI(NationalInstrument) Data Acquisition Device to acquire sound signals, use far-filed acousticholography algorithm to process data and reconstruct acoustic filed. After backsteppingthe distribution of acoustic field, attach color map which include sound pressure andsound source position information to the background picture. Reach the purpose ofvisualization of acoustic field noise source.