To provide a device for improving a sound signal quality, which discriminates the radio environment of a signal transmission line to detect a click noise and improves the quality of the sound signal.
The device is provided with a click noise detection circuit (22) and a click noise suppression circuit (23), and the circuit (22) calculates an average value in a short section of a reception ADPCM code and discriminates the radio environment of the signal transmission line in accordance with this average value and regards a clock noise as occurring to output a click noise detection signal when the average value exceeds a threshold assigned to each radio circumstances, and the circuit (23) sets a speed coefficient of an ADPCM decoder (21) to 0 with respect to a frame where a frame error detection signal indicating that a frame error of the reception ADPCM code has been detected and the click noise detection signal are detected together.
O UMETADA
SHINSHIYOU HIDEJI
SHINOHARA YOSHINORI
SEKI KAZUHIKO
