Temperature effects on the mechanical-acoustic properties of condenser microphones: experimental characterization
* Presenting author
Condenser microphones are originally designed for airborne acoustic measurements. For this reason, their electro-mechanical behaviour is well-known and characterized almost in atmospheric conditions. However, more and more applications, such as acoustic thermometry, gas metrology or thermoacoustics, require the use of electrostatic transducers (as acoustic transmitters or receivers) in gas conditions that differ significantly from atmospheric ones.Previous experiments using the electrostatic actuator technique evidenced the relevant influence of the static pressure and the type of gas on the frequency response of condenser microphones. The same technique is used here to characterize the mechanical properties of a 1/4’’ microphone’s membrane in vacuum at temperatures between 80 K and 300 K. The resonance properties of the membrane are then obtained and expressed as function of the temperature. Thus, they are used in comprehensive models of condenser microphones whose validity as function of the temperature is experimentally checked. Also, an improved model of condenser microphone coupled to an electrostatic actuator is developed for the sake of this work.By improving the supporting models and experimental methods, this work is expected to drive the design of new electrostatic transducers and promote an advance of the calibration procedures, as required for specific applications.