FIELD: physics, acoustics.
SUBSTANCE: invention relates to a system and a method of enhancing a decoded tonal sound signal, particularly a music signal coded using a speech codec, by reducing the level of quantisation noise in regions of the spectrum exhibiting low energy. In the system for enhancing a tonal sound signal decoded by a decoder of a speech codec in response to a received coded bit stream, the spectral analyser reacts to the decoded tonal sound signal to produce spectral parameters representative of the decoded tonal sound signal. The spectral parameters contain spectral energy calculated by the spectral analyser in the frame of the decoded tonal sound signal. A classifier of the decoded tonal sound signal into a plurality of different sound signal categories has a finder of deviation of variation of the calculated frame spectral energy over a number of previous frames of the decoded tonal sound signal. A reducer of a quantisation noise reduces quantisation noise in low-energy spectral regions of the decoded tonal sound signal in response to the spectral parameters from the spectral analyser and classification of the decoded tonal sound signal into a plurality of different sound signal categories.
EFFECT: enhanced decoding of a tonal sound signal, eg, a music signal.
26 cl, 6 dwg, 1 tbl
