An apparatus for processing an audio input signal comprising one or more audio channels to obtain an audio output signal according to an embodiment is provided. The apparatus comprises a reverberation gain determiner (110) configured to determine reverberation gain information depending on the audio input signal. Moreover, the apparatus comprises a signal processor (120) configured to obtain the audio output signal depending on the reverberation gain information by adding artificial reverberation to the audio input signal or to a preprocessed audio signal, which depends on the audio input signal.