An electronic device receives audio from an audio source and outputs the audio via speakers of the device. While outputting the audio via the speakers, the device senses its surrounding environment, and adjusts its operation, based on the sensed environment, to alert a listener wearing the device. The adjustment may comprise generation of one or more audio, visual, and/or vibration notifications to the listener using the device. A volume of the audio output via the speakers may be adjusted based on the sensed surrounding environment. The device may detect whether a first condition is present in the surrounding environment, decrease the volume when the first condition is detected in the surrounding environment, and increase the volume when the first condition is not detected in the surrounding environment.