A novel two-dimensional sound particle velocity probe for source localization and free field measurements in a diffuse field

摘要

Sound can be described as variations in sound pressure and sound particle velocity. Sound pressure is most commonly used for measuring acoustical parameters of rooms and sound sources. Sound velocity however yields more acoustical information about rooms and sources simply because the velocity is a vector quantity, whereas the pressure is only a scalar. Another important aspect is the fact that the diffuse field is not measured with a velocity sensor the same way a microphone would, but only partially because of the directivity. Combinations of more than one velocity sensor can further increase the ratio between direct and diffuse sound, and some combinations can even be proven to contain no diffuse sound at all in case of an ideal diffuse sound field. We used two velocity sensors so that we are able to measure two independent sound velocity vectors that are projected on a surface. These two signals can be used to obtain more information about position of the source of the incoming sound signal, and further the two signals yield information about the direct and indirect sound. By using the cross correlation of the two signals, the signal to noise ratio is also improved largely compared with only one sensor. With use of this technique we are able to measure direct sound field radiated from an acoustical source in a reverberant room, the position of the sound source, and acoustical properties of the room. The room should however approximate an ideal diffuse sound field; but this property can be examined with the use of two velocity sensors.