Acoustic electromechanical resonance filters

A mechanical resonator is used as the basis of an acoustically excited filter. The resonator, which is essentially a simple brass, reed-like structure, is located in a magnetic field generated by a permanent magnet. In the presence of a sound field, the mechanical resonator is excited and its motion is detected by measuring the induced voltage across its terminals. The frequency response, the sound pressure sensitivity and the directional properties of various resonant elements were measured so as demonstrate their ability to function as resonant sound sensors. The experimental results show that the proposed device may work very well as a frequency indicator since in the case of light damping it is able to detect small frequency deviations. Furthermore, a reduction of the device dimensions is discussed, in order to implement a resonant microsystem that functions according to an applicable electrodynamic signal pickup scheme.