The US Patent and Trademark Office has published a patent application from Apple, which relates to a spatial audio rendering processor for AirPods Max, which can calibrate the audio beamforming array processing algorithm to respond to the changes in the physical shape of wearable audio devices. It is unclear whether Apple's patent describes the future development direction of its H1 chip.
beamforming is an audio signal processing operation in which a transducer array is used for directional sound transmission or reception. For example, in the case of directional sound reception, usually a microphone array with two or more microphones captures sound and extracts spatial audio information through processing.
for example, in the case where a microphone array picks up multiple sound sources, beamforming allows an audio signal representing one of the multiple sound sources to be extracted. Thereby allowing the microphone array to focus sound pickup on the sound source while attenuating (or filtering) other sound sources.
regarding directional sound transmission, a speaker array with two or more speakers usually generates a beam pattern to project sound in different directions.
for example, a beamformer may receive an input audio channel of sound program content (e.g., music) and convert the input audio channel into several driving signals to drive speakers of a speaker array to generate a sound beam pattern.
one aspect of apple's invention is to perform transfer function measurement for each different physical arrangement of a beamforming array (such as a microphone array or a speaker array) of a wearable device to consider various shapes of the wearable device.
these measurements can be made in a dedicated anechoic room, in which wearable devices are placed and deformed (manipulated) into a given shape.
in order to measure the microphone array, speakers are placed around the wearable device, and each speaker represents a sound source in the acoustic space.
each speaker generates sound independently, so as to measure the transfer function of each microphone in the array for this position of the sound source.
another aspect of apple's invention involves determining the physical arrangement of a beamforming array by using at least one of a variety of methods.
the acoustic method involves measuring the near-field transfer function of at least one audio element of a beamforming array, which represents the acoustic transmission path between the audio element and a known location.
there is also an optical method to associate each physical layout of the array with the image data captured by the camera, and a mechanical sensing method to associate a given physical layout with mechanical sensing data.
information from: patentlyapple.