Electro-acoustic transducers with cellular polymer electrets

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