Provided is a device for improving voice signal in quality by discriminating
a radio environment of a signal transmission path and detecting a click noise.
The device for improving voice signal in quality calculates an average value for
a short interval of a received ADPCM code, identifies from such average value the
nature of a radio environment of a signal transmission path, and considers that
a click noise is occurred when the average value exceeds a threshold value assigned
radio environment. The present invention comprises a click noise detector (22)
for outputting a click noise detecting signal, and a click noise suppressing circuit
for suppressing the click noise by setting the velocity coefficient of an ADPCM
decoder (21) as "0" for a frame in which a frame error detecting signal,
which represents the detection of a frame error of the received ADPCM code, and
a click noise detecting signal are both detected.
