A directional microphone array for acoustic studies of wind tunnel models

Aeroacoustic Noise Measurements of a Wind Turbine with BSDS Blades Using an Acoustic Array

“…Recently, acoustic arrays 3,4 have been developed to identify locations of noise sources as well as noise amplitudes. Acoustic arrays are a relatively new measurement devices for aeroacoustic noise 5,6 , but are based on well known signal processing schemes for phased arrays 7 . In the past two decades, phased microphone arrays have seen many applications to the field of rotorcraft and aircraft noise both inside the wind tunnel and in the field [8][9][10] .…”

Effect of surface treatment on array microphone self-noise

“…Phased arrays have all but replaced earlier methods for locating noise sources such as dual sideline correlation 2 , acoustic mirrors 3,4 and sound intensity 5 . Whether processing is done in the time domain 6,7 or the frequency domain 8,9 , the combined contributions of multiple microphones enable researchers to distinguish and quantify noise sources in a manner not possible with individual microphones. Further, the phased microphone array's ability to discriminate against background noise makes it particularly useful for airframe noise studies, as the noise sources are usually quieter than the prevalent wind tunnel background noise.…”

Effect of directional array size on the measurement of airframe noise components

“…These systems are still found to be useful even today, especially in some larger test facilities 6,7 . Also in the 1970's, measurements involving directional (or phased) arrays of microphones were examined 8,9 using time delay and sum techniques. By adjusting for propagation time delays from particular source locations to the microphones, one is able to localize noise production in basically an equivalent fashion to that of the acoustic mirror approach, without the requirement to mechanically move the system.…”