NOISE REDUCTION METHOD AND APPARATUS

摘要

APPARATUS FOR NOISE REDUCTION AND NOISE PROCESSING METHODS FOR REDUCING NOISE IN AUDIO SIGNALS ARE PRESENTED. THE NOISE LEVEL OF AN INPUT SIGNAL AT AN INPUT TERMINAL (23) IS MEASURED AND THE NOISE-TO-SIGNAL RATIO IS ESTABLISHED. A REDUCED VOICE ACTIVITY DETECTOR (15) IS USED TO DETERMINE WHETHER THE INPUT SIGNAL COMPRISES SPEECH OR NOT. IF THE MEASURED NOISE LEVEL EXCEEDS A THRESHOLD LEVEL A SWITCH CONNECTS THE INPUT SIGNAL TO MEANS FOR NOISE REDUCATION. HOWEVER, IF THE MEASURED NOISE LEVEL DOES NOT EXCEED THE THRESHOLD LEVEL, I.E. WHEN NOISE REDUCATION IS NOT NEEDED, THE SWITCH DISCONNECTS THE MEANS FOR NOISE REDUCATION AND THE INPUT SIGNAL IS PASSED UNCHANGED. POWER IS SAVED BY POWERING OFF THE MEANS FOR NOISE REDUCATION WHEN IT IS NOT NEEDED.FIGURE 1