Electro-acoustic transducers with cellular polymer electrets

1) The possibility of finding range from the propagation delay time was confirmed in the short-distance domain. 2) The sound pressure level of the regular dodecahedron Tx reached 103 dB / 78 Vrms at 1m and a frequency of 140 kHz. 3) The regular dodecahedron Tx exhibited almost omnidirectional directivity for M-series pseudorandom noise.