To provide a speech processor capable of performing signal processing to a voice signal by following the change of the voice, even if the voice whose volume level often changes.

The speech processor equipped in a multi-function product measures the signal level Lc of the voice signal which is transferred between the multi-function product and communication destination equipment (S145), and updates a sound parameter group (S165) when the absolute value (|Lp-Lc|) of difference between a peak value Lp stored in an RAM and the signal level Lc measured in the processing of S145 is larger than a predetermined threshold Lh (S150:yes) and also the signal level Lc measured in the processing of S145 is larger than -30dBm (S155; yes). As a result, the optimizing of the sound volume and the cutting of noise component corresponding to the volume and the canceling of echo, etc., are applied to the voice signal according to the sound volume, and the voice signal which is transferred between the product and the communication destination equipment is corrected to the voice easy to hear.