| 摘要 |
In a loudspeaking telephone arrangement, there are separate channels for outgoing speech (A-Tx) and incoming speech (A-Rx), and the channels are sampled at intervals. The results of these samplings, which represent the amplitudes of the speech in those channels are each compared by a microprocessor with a preset threshold. The background noise level is also sampled and the result used to adjust the speech channel threshold. Each channel has an attenuator, and that is adjusted so that attenuation is reduced in the presence of speech and increased in the absence thereof. The adjustment on the basis of background noise enables the current state of the channels to be taken into account. |
