Loudness control for user interactivity in audio coding systems

An audio processor for processing an audio signal (100), comprises: an audio signal modifier (2) for modifying the audio signal (100) in response to a user input (200); a loudness controller (6) for determining a loudness compensation gain (C) based on a reference loudness (Lref) or a reference gain (gi) and a modified loudness (Lmod) or a modified gain (hi), where the modified loudness (Lmod) or the modified gain (hi) depends on the user input; and a loudness manipulator (5) for manipulating a loudness of a signal (101) using the loudness compensation gain (C).