Microphones play an important role in the occasions where sounds need picking up, such as concerts, awarding ceremonies, and sport game broadcasts. In order to achieve the optimized sound pickup quality, professional microphones are normally used in such occasions. The acoustic pressure of sounds originates from the particle velocity. Therefore, purer acoustic signals will be obtained if we directly measure the particle velocity rather than indirectly measure the acoustic pressure.
H. E. de Bree disclosed a particle velocity-based microphone in a paper “The Microflown: an acoustic particle velocity sensor, Acoustics Australia Vol. 31, December (2003) No. 3, pp. 91-94”, wherein a platinum sensor is used to detect a particle velocity, and a thermal flow algorithm is used to process the particle velocity. The prior-art microphone can precisely pick up sounds. However, it is very expensive.
E. Kreyszig disclosed an acoustic pressure microphone system in a book “Advanced Engineering Mathematics (John Wiley & Sons, Inc., New York, 2006), pp. 798-801”, wherein microphone pairs are used to approximate the acoustic pressure gradient in a finite-differential way to obtain the particle velocity. However, the sound signals are likely to be distorted by noise and the mismatch of microphones.
Therefore, it is expected to develop a method of using common and inexpensive sensors to precisely measure the particle velocity.