A headphone system includes a calibration microphone for performing a calibration routine with a user. The calibration microphone receives a stimulus signal emitted by the headphone system and generates a response signal indicating variations in the stimulus signal that arise due to physiological attributes of the user. Based on the stimulus signal and the response signal, the calibration engine generates response data. The calibration engine processes the response data based on a headphone transfer function (HPTF) associated with the headphone system in order to create an inverse filter that can reduce or remove acoustic variations caused by the headphone system. The calibration engine generates a personalized HRTF for the user based on the response data and the inverse filter. The personalized HRTF can be used to implement highly accurate 3D audio and is thereby well-suited for applications to immersive audio and audio-visual entertainment.

The various implementations described herein include methods, devices, and systems for automatic audio equalization. In one aspect, a method is performed at an electronic device that includes speakers, microphones, processors and memory. The electronic device outputs audio user content from the speakers and automatically equalizes subsequent audio output of the device without user input. The automatic equalization includes: (1) obtaining audio content signals, including receiving outputted audio content at each microphone; (2) determining from the audio content signals phase differences between microphones; (3) obtaining a feature vector based on the phase differences; (4) obtaining a frequency correction from a correction database based on the obtained feature vector; and (5) applying the obtained frequency correction to the subsequent audio output.

Methods and apparatus improve a user experience during telephone calls or other forms of communication in which a listener localizes electronically generated binaural sounds. The sound is convolved or processed to a location that is behind or near a source of the sound so that the listener perceives the location of the sound as originating from the source of the sound.