investigation and comparison of three popular ultrasonic generators (pzt, pvdfemfi) for employing in acoustic scaling

acoustic scaling is one of the efficient techniques for measuring acoustic parameters of large and luxury places. due to the range of acoustic scaling frequency, an airborne ultrasonic transducer has been used for transporting the power to the air. one major problem of ultra sonic transducers, radiating acoustic energy into the air, is to find the properacoustic impedance of one or more matching layers. this work aims at developing an original solution to the acoustic impedance mismatch between transducer and air. therefore we consider three piezoelectrics, pzt, pvdf, and emfi transducers and air that have high acoustic impedance deference. we proposed the use of a genetic algorithm (ga) toselect the best acoustic impedances for matching layers from the material database for a narrow band ultrasonic transducer that works at afrequency below the 1mhz by considering attenuation. this yields ahighly more efficient transmission coefficient. also, the results showed that by using the increasing number of layers we can increase our chance to find the best sets of materials with valuable both in acoustic impedance and low attenuation. precisely, the transmission coefficient is almost higher than 80% for the more studied cases.