Low-complexity tonality-adaptive audio signal quantization

Audio encoder for encoding an audio signal so as to produce therefrom an encoded signal, the audio encoder comprising:

• a framing device configured to extract frames from the audio signal;
• a quantizer configured to map spectral lines of a spectrum signal derived from the frame of the audio signal to quantization indices, wherein the quantizer comprises a dead-zone, in which the spectral lines are mapped to quantization index zero;
• and
• a control device configured to modify the dead-zone;
• wherein the control device comprises a tonality calculating device configured to calculate at least one tonality indicating value for at least one spectrum line or for at least one group of spectral lines,
• wherein the control device is configured to modify the dead-zone for the at least one spectrum line or the at least one group of spectrum lines depending on the respective tonality indicating value in such way that the dead-zone for the at least one spectrum line or the at least one group of spectral lines is selected before mapping the at least one spectrum line or the at least one group of spectral lines to the quantization indices.