1. A computer-implemented method comprising: determining, by one or more processors, whether audio input data received after ceasing output of a first instance of a recurring audible alert tone includes voice activity; and determining, by the one or more processors, whether to delay output of a successive instance of the recurring audible alert tone, that by default would occur at a default time after a default time interval, until a delayed time after a delay time interval longer than the default time interval based on determining whether the audio input data includes voice activity.