Future models of the AirPods Max may sport a “virtual acoustic system.” Apple has been granted a patent (number 11,284,195) for a “system to move sound into and out of a listener’s head using a virtual acoustic system.”
About the patent
A virtual acoustic system is an audio system that gives a listener the illusion that a sound is emanating from somewhere in space when in fact the sound is emanating from loudspeakers placed elsewhere. One common form of a virtual acoustic system is one that uses a combination of headphones and binaural digital filters to recreate the sound as it would have arrived at the ears if there were a real source placed somewhere in space.
Summary of the patent
Here’s Apple’s abstract of the patent with some technical details: “In a device or method for rendering a sound program for headphones, a location is received for placing the sound program with respect to first and second ear pieces. If the location is between the first ear piece and the second ear piece, the sound program is filtered to produce low-frequency and high-frequency portions.
“The high-frequency portion is panned according to the location to produce first and second high-frequency signals. The low-frequency portion and the first high-frequency signal are combined to produce a first headphone driver signal to drive the first ear piece. A second headphone driver signal is similarly produced. The sound program may be a stereo sound program. The device or method may also provide for a location that is between the first ear piece and a near-field boundary. Other aspects are also described.”