Methods and apparatus for adjusting a level of an audio signal

An audio processing apparatus for adjusting a level of an audio signal, the audio processing apparatus comprising:

• an analysis filterbank for dividing an audio signal into a plurality of frequency bands;
• a parameter generator for obtaining modification parameters for at least one of the plurality of frequency bands, the modification parameters comprising filter coefficients and amplitude scale factors, each amplitude scale factor respectively operating in a frequency band of the plurality of frequency bands and each amplitude scale factor representing an average energy over the frequency band and a time segment;
• a first processor for deriving gain factors for at least one of the plurality of frequency bands, the gain factors determined based on the amplitude scale factors;
• a smoother for smoothing the gain factors, wherein the smoothing of the gain factors is optional;
• a second processor for determining a level of noise from noise compensation factors;
• a first adjuster for applying the gain factors to at least one of the frequency bands to generate gain adjusted frequency bands;
• a second adjuster for adjusting the level of noise based on the gain adjusted frequency bands;
• a filter for filtering at least one of the frequency bands, the filter generated with the filter coefficients, wherein the filter coefficients are applied to time-varying filters;
• and
• a synthesis filterbank for synthesizing the plurality of frequency bands to generate an output audio signal;
• wherein the gain factors are both time and frequency varying.