Patent ID: 8045731
Filing Date: 2011-10-25
Classification: H04R

Abstract:
1. A sound quality adjustment device comprising, for at least one of sound signals of multiple channels; a filter circuit that extracts a sound signal of a predetermined frequency band from an input sound signal; a boost circuit that performs dynamic range expansion/contraction on the sound signal, extracted by said filter circuit, in accordance with an input level of the sound signal; an adder that adds together the input sound signal and the sound signal outputted by said boost circuit; and a decay processing circuit provided between said filter circuit and said boost circuit, said decay processing circuit gradually attenuating an output level in accordance with lowering of the level of the sound signal extracted by said filter circuit, said decay processing circuit sampling an input sound signal at predetermined time intervals, comparing a sample value at the current time with an output value at the last sample time, and selecting the higher of the compared two sample values as an output value at the current time, so that, when the output value at the last sample time decreases, the value at the last sampling time is attenuated at a decay rate which increases with the passage of time and is set as the output value at the current time.