1. A method of operating a decoder comprising: obtaining a vector d(k) comprising quantized Modified Discrete Cosine Transform (MDCT) domain coefficients of a time segment of an audio signal; deriving a processed vector {circumflex over (d)}(k) by applying a post-filter directly on the vector d(k), the post-filter being configured to have a transfer function H(k), 
 H ( k )={(abs[ d ( k )])/(max[abs( d )])} a(k) , which is a compressed version of an envelope of the vector d(k), where k goes from 1 to the number of MDCT domain coefficients of the time segment of the audio signal, where max[abs(d)] is a maximum of an absolute value of the vector d(k), and a(k) is an emphasis component configured to control a post-filter aggressiveness over the MDCT spectrum; and deriving a signal waveform by performing an inverse MDCT transform on the processed vector {circumflex over (d)}(k).