A signal processor comprising: a modelling block, configured to receive a frequency-domain-input-signal, a fundamental-frequency-signal representative of a fundamental frequency of the frequency-domain-input-signal; and configured to provide a pitch-model-signal based on a periodic function, the pitch-model-signal spanning a plurality of discrete frequency bins, each discrete frequency bin having a respective discrete frequency bin index, wherein within each discrete frequency bin the pitch-model-signal is defined by: the periodic function; the fundamental frequency; the frequency-domain-input-signal; and the respective discrete frequency bin index. The signal processor further comprises a manipulation block, configured to provide an output-signal based on the frequency-domain-input-signal and the pitch-model-signal.