FIELD: acoustics.
SUBSTANCE: invention relates to acoustics, particularly to an apparatus for modifying an audio signal, and comprises an envelope shape determiner, a filter bank processor, a signal processor, a combiner and an envelope shaper. Envelope shape determiner calculates envelope shape coefficients of audio signal, filter bank provides band pass filtering, signal processor corrects signal with limited bandwidth. Then, a plurality of signals with given a frequency subband are combined to obtain an audio signal of a time slot. Envelope shaper generates envelope of audio signal including envelope shape coefficients. Envelope shape determiner is configured to determine envelope shape coefficient based on frequency prediction. Envelope converter consists of coefficient converter and multiplier. Filter bank processor comprises a prediction filter, a signal subtractor unit and a filter bank, and envelope shaper calculates energy ratio of energy margin of audio signal and energy content of residual audio signal.
EFFECT: improved sound quality.
14 cl, 23 dwg, 4 tbl
