Automatic volume control system for compensation of volume difference between TV channels

The sound levels of TV channels vary greatly according to modulation and demodulation rates. When the television channel or input mode is changed, users have to adjust the volume in order to obtain a proper level of sound. In this paper, an automatic volume control system is proposed to compensate for the volume difference which occurs with channel changing. A simple power estimation based on the symmetry property of sound and a selective volume control algorithm using a 3-step compensation are presented. The proposed system is designed using consumer ICs for easy implementation to current audio media. In addition, a filter is used to revise the system function in order to model the frequency response of the designed system upon that of a human at a normal hearing level. For the experimental results in a TV set, it is shown that the volume fluctuation is considerably reduced.