Informed postprocessing for auditory roughness removal for low-bitrate audio coders

In perceptual audio coding using very low bitrates, modulation artifacts can be introduced onto tonal signal components, which are often perceived as auditory roughness. These artifacts may occur for instance due to quantization errors or may be added when using an audio bandwidth extension, which sometimes causes an irregular harmonic structure at the borders of replicated bands. Especially, the roughness artifacts due to quantization errors are difficult to mitigate without investing considerably more bits in encoding of tonal components. We propose a novel technique to remove these roughness artifacts at the decoder side controlled by a small amount of guidance information transmitted by the encoder.