Abstract: The present disclosure provides an audio signal processing circuit for receiving an input signal derived from sound sensed by an acoustic sensor, the audio signal processing circuit comprising: a trigger phrase detection module for monitoring the input signal for at least one feature of a trigger phrase and outputting a trigger signal if one said feature is detected; wherein the trigger signal is ignored if a time interval between an occurrence of the at least one feature and an occurrence of a feature indicative of a start of speech contained in the input signal is greater than a threshold amount of time.