A device may be configured to alert a user while the user is listening to audio over headphones. For example, the device may be configured to alert the user of the device, such as by reducing the volume of an audio signal output through the headphones and/or by providing a visual alert to the user on a display of the device. The device may compare a volume level of an outputted audio signal to a threshold. The device may activate a microphone based on the comparison of the volume level to the threshold. When the microphone is activated, the device may provide an alert to a user based on a determination that a received audio signal includes a portion that corresponds to a predetermined value.