Abstract
A method to measure particle velocity by using microphones includes the steps of: placing a sound source, a first microphone and a second microphone in a space, wherein the first microphone is located in a first position between the sound source and the second microphone, and the second microphone is in a second position farther away from the sound source than the first position; performing a measurement to the sound source by the first microphone and the second microphone to obtain a first sound pressure and a second sound pressure respectively; establishing a free-space Green's function based on a equivalent source model by using the first position and the second position, and establishing a sound pressure function based on the equivalent source models by using the first sound pressure and the second sound pressure; establishing a state-space of sound amplitude by using the free-space Green's function with the sound pressure function to obtain a particle velocity. Accordingly, the method is not only has the good accuracy, but also has the advantage of lower cost.