Speech signal transmitting and receiving apparatus with noise sensitive volume control

A speech signal transmitting and receiving apparatus comprising:

• a speech signal encoder for compressing input speech signals by digital signal processing for high quality voice transmission at a low bit rate and for producing patterns of analytic parameters from the input speech signal;
• a transmitting and receiving circuit for transmitting the compressed speech signals output by said speech signal encoder and for receiving compressed speech signals transmitted from another transmitter and reproducing a corresponding received sound;
• noise domain detection means supplied with patterns of analytic parameters produced by said speech signal encoder during compression of the input speech signals for determining a noise domain in which only noise exists in the input speech signal;
• noise level detecting means for detecting a noise level of the input speech signal in the noise domain;
• and
• means for controlling a volume of the corresponding received sound responsive to the noise level detected by said noise domain detection means.