| 摘要 |
<p>A public address system having a microphone, an amplifier which amplifies the output from the microphone and a speaker assembly which receives the output from the amplifier and reproduces a sound, in which the microphones has provided with a transmitter generating an electromagnetic wave and the speaker assembly has two receiving coils disposed perpendicular with each other. In this case, the outputs from the receiving coils are used to control the level of an audio signal applied to the speaker assembly and to thereby avoid occurrence of howling.</p> |
