Apparatus for post-processing an audio signal, comprising: a converter for converting the audio signal into a time-frequency representation; a transient location estimator for estimating a location in time of a transient portion using the audio signal or the time-frequency representation; and a signal manipulator for manipulating the time-frequency representation, wherein either i) the signal manipulator is configured to reduce or eliminate a pre-echo in the time-frequency representation at a location in time before the transient location, wherein the signal manipulator comprises a pre-echo threshold estimator for estimating pre-echo thresholds for spectral values in the time-frequency representation within a pre-echo width, wherein the pre-echo thresholds indicate amplitude thresholds of corresponding spectral values subsequent to the pre-echo reduction or elimination, and wherein the pre-echo threshold estimator is configured to determine the pre-echo thresholds using a weighting curve having an increasing characteristic from a start of the pre-echo width to the transient location, or wherein ii) the signal manipulator is configured to perform a shaping of the time-frequency representation at the transient location to amplify an attack of the transient part, wherein the signal manipulator is configured to divide the time-frequency representation at the transient location into a sustained part and the transient part, wherein the signal manipulator is configured to only amplify the transient part and to not amplify the sustained part, and wherein the signal manipulator is configured to combine the sustained part and the amplified transient part to obtain a post-processed audio signal. a converter for converting the audio signal into a time-frequency representation; a transient location estimator for estimating a location in time of a transient portion using the audio signal or the time-frequency representation; and a signal manipulator for manipulating the time-frequency representation, wherein either i) the signal manipulator is configured to reduce or eliminate a pre-echo in the time-frequency representation at a location in time before the transient location, wherein the signal manipulator comprises a pre-echo threshold estimator for estimating pre-echo thresholds for spectral values in the time-frequency representation within a pre-echo width, wherein the pre-echo thresholds indicate amplitude thresholds of corresponding spectral values subsequent to the pre-echo reduction or elimination, and wherein the pre-echo threshold estimator is configured to determine the pre-echo thresholds using a weighting curve having an increasing characteristic from a start of the pre-echo width to the transient location, or wherein ii) the signal manipulator is configured to perform a shaping of the time-frequency representation at the transient location to amplify an attack of the transient part, wherein the signal manipulator is configured to divide the time-frequency representation at the transient location into a sustained part and the transient part, wherein the signal manipulator is configured to only amplify the transient part and to not amplify the sustained part, and wherein the signal manipulator is configured to combine the sustained part and the amplified transient part to obtain a post-processed audio signal. i) the signal manipulator is configured to reduce or eliminate a pre-echo in the time-frequency representation at a location in time before the transient location, wherein the signal manipulator comprises a pre-echo threshold estimator for estimating pre-echo thresholds for spectral values in the time-frequency representation within a pre-echo width, wherein the pre-echo thresholds indicate amplitude thresholds of corresponding spectral values subsequent to the pre-echo reduction or elimination, and wherein the pre-echo threshold estimator is configured to determine the pre-echo thresholds using a weighting curve having an increasing characteristic from a start of the pre-echo width to the transient location, or wherein ii) the signal manipulator is configured to perform a shaping of the time-frequency representation at the transient location to amplify an attack of the transient part, wherein the signal manipulator is configured to divide the time-frequency representation at the transient location into a sustained part and the transient part, wherein the signal manipulator is configured to only amplify the transient part and to not amplify the sustained part, and wherein the signal manipulator is configured to combine the sustained part and the amplified transient part to obtain a post-processed audio signal.