A system and method for interjecting ambient background sounds into a set of headphones is provided. The system monitors an ambient sound environment and compares the ambient sound environment to a preset set of sound characteristics (e.g., frequency signatures, amplitudes and durations) in order to detect important or critical background sounds (e.g., alarm, horn, directed vocal communications, crying baby, doorbell, telephone, etc.). When a critical background sound is detected, the system interjects either a notification signal or a portion of the ambient background into the audio stream, thus alerting a user of a potentially important sound or event occurring within their immediate vicinity.