Receiver, comprising: a demultiplexer configured for extracting an encoded mono signal and stereo-width parameters from a bitstream; a decoder configured for decoding the encoded mono signal; characterised by: a pseudo-stereo generator configured for applying a stereo width to the decoded mono signal, and an apparatus configured for interpolating between several time consecutive stereo-width parameters, a stereo-width parameter representing a difference signal or a cross-correlation of an original left and right channel, the apparatus configured for interpolating comprising: a calculator configured for calculating an interpolated value by smoothing stereo-width gain values over a time segment having several stereo-width parameters, a stereo-width gain value being a function of a corresponding stereo-width parameter, wherein the pseudo-stereo generator is configured to split the decoded mono signal in two signals, to delay the decoded mono signal to obtain at least one delayed version of the decoded mono signal, and to add with opposite signs (223, 225) the at least one delayed version to the two signals at at least one level controlled by the interpolated value. a demultiplexer configured for extracting an encoded mono signal and stereo-width parameters from a bitstream; a decoder configured for decoding the encoded mono signal; characterised by: a pseudo-stereo generator configured for applying a stereo width to the decoded mono signal, and an apparatus configured for interpolating between several time consecutive stereo-width parameters, a stereo-width parameter representing a difference signal or a cross-correlation of an original left and right channel, the apparatus configured for interpolating comprising: a calculator configured for calculating an interpolated value by smoothing stereo-width gain values over a time segment having several stereo-width parameters, a stereo-width gain value being a function of a corresponding stereo-width parameter, a pseudo-stereo generator configured for applying a stereo width to the decoded mono signal, and an apparatus configured for interpolating between several time consecutive stereo-width parameters, a stereo-width parameter representing a difference signal or a cross-correlation of an original left and right channel, the apparatus configured for interpolating comprising: a calculator configured for calculating an interpolated value by smoothing stereo-width gain values over a time segment having several stereo-width parameters, a stereo-width gain value being a function of a corresponding stereo-width parameter, a calculator configured for calculating an interpolated value by smoothing stereo-width gain values over a time segment having several stereo-width parameters, a stereo-width gain value being a function of a corresponding stereo-width parameter, wherein the pseudo-stereo generator is configured to split the decoded mono signal in two signals, to delay the decoded mono signal to obtain at least one delayed version of the decoded mono signal, and to add with opposite signs (223, 225) the at least one delayed version to the two signals at at least one level controlled by the interpolated value. to split the decoded mono signal in two signals, to delay the decoded mono signal to obtain at least one delayed version of the decoded mono signal, and to add with opposite signs (223, 225) the at least one delayed version to the two signals at at least one level controlled by the interpolated value.