Apple has been granted a patent (number 11,265,670) for “coordinated tracking for binaural audio rendering.” It involves the sound systems in its various devices — including an “Apple Car” and an augmented reality/virtual reality headset.
About the patent
Binaural recording is a method of recording sound that uses two microphones, arranged with the intent to create a 3-D stereo sound sensation for the listener of actually being in the room with the performers or instruments.
Binaural headphones and sound systems simulate virtual sound sources. To achieve realistic virtual sound sources, head-tracking may be used to anchor the virtual sound source to a reference frame, e.g., a room.
Head-tracking systems may incorporate orientation sensors to allow an audio engine to predict an orientation of the binaural headphones relative to the reference frame. Apple wants its audio devices to be able to simulate the virtual sound source in an appropriate direction as a listener’s head turns.
Summary of the patent
Here’s Apple’s abstract of the patent with technical details: “A binaural sound reproduction system, and methods of using the binaural sound reproduction system to dynamically re-center a frame of reference for a virtual sound source, are described. The binaural sound reproduction system may include a reference device, e.g., a mobile device, having a reference sensor to provide reference orientation data corresponding to a direction of the reference device, and a head-mounted device, e.g., headphones, having a device sensor to provide device orientation data corresponding to a direction of the head-mounted device.
“The system may use the reference orientation data to determine whether the head-mounted device is being used in a static or dynamic use case, and may adjust an audio output to render the virtual sound source in an adjusted source direction based on the determined use case. Other embodiments are also described and claimed.”