一声频定向换能器，以定向发射超声波给接听者，其中该超声频段部分经空气自解调而还原为原音频信号。
Because the ultrasonic wave has the directivity, the audible audio frequency demodulated from the interior of the ultrasonic wave also has the directivity and forms a directional audible sound.
一声频定向换能器，以定向发射超声波给接听者，其中该超声频段部分经空气自解调而还原为原音频信号。
Because the ultrasonic wave has the directivity, the audible audio frequency demodulated from the interior of the ultrasonic wave also has the directivity and forms a directional audible sound.
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