An apparatus for modifying an audio signal includes a filterbank processor, a fundamental determiner, an overtone determiner, a signal processor and a combiner. The filterbank processor generates a plurality of bandpass signals based on an audio signal and the fundamental determiner selects a bandpass signal of the plurality of bandpass signals to obtain a fundamental bandpass signal. The overtone determiner identifies a bandpass signal of the plurality of bandpass signals fulfilling an overtone criterion regarding the selected fundamental bandpass signal to obtain an overtone bandpass signal associated to the selected fundamental bandpass signal. The signal processor modifies the selected fundamental bandpass signal based on a predefined modification target. Additionally, the signal processor modifies an identified overtone bandpass signal associated to the selected fundamental bandpass signal depending on the modification of the selected fundamental bandpass signal. Further, the combiner combines the plurality of bandpass signals to obtain a modified audio signal.