# US 11,122,383 B2 · Near-field audio rendering > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,122,383 B2 - Document ID: US11122383B2 - Status: Granted - Kind: B2 - Application number: 16/593,943 - Filed: 2019-10-04 - Published: 2020-04-09 - Granted: 2021-09-14 - Earliest claimed: 2018-10-05 - Assignees: Magic Leap, Inc. - Applicants: Magic Leap, inc. - Inventors: Remi Samuel Audfray; Jean-Marc Jot; Samuel Charles Dicker; Mark Brandon Hertensteiner; Justin Dan Mathew; Anastasia Andreyevna Tajik; Nicholas John LaMartina - Web page: https://patentgrep.com/patent/US11122383B2 ## CPC - H04S 7/304: {For headphones} - H04R 5/033: Headphones for stereophonic communication {(details thereof, e.g. relating to batteries, cables or control elements H04R1/10)} - H04R 5/04: Circuit arrangements, {e.g. for selective connection of amplifier inputs/outputs to loudspeakers, for loudspeaker detection, or for adaptation of settings to personal preferences or hearing impairments (combinations of amplifiers H03F3/68; stereophonic systems H04S)} - H04S 3/008: {in which the audio signals are in digital form, i.e. employing more than two discrete digital channels (data reduction aspects thereof based on psychoacoustics G10L19/02)} - H04R 2499/15: Transducers incorporated in visual displaying devices, e.g. televisions, computer displays, laptops - H04S 2400/01: Multi-channel, i.e. more than two input channels, sound reproduction with two speakers wherein the multi-channel information is substantially preserved - H04S 2400/11: Positioning of individual sound objects, e.g. moving airplane, within a sound field (H04S2420/13 takes precedence) - H04S 2420/01: Enhancing the perception of the sound image or of the spatial distribution using head related transfer functions [HRTF's] or equivalents thereof, e.g. interaural time difference [ITD] or interaural level difference [ILD] - H04S: STEREOPHONIC SYSTEMS - H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K) ## Abstract Examples of the disclosure describe systems and methods for presenting an audio signal to a user of a wearable head device. According to an example method, a source location corresponding to the audio signal is identified. An acoustic axis corresponding to the audio signal is determined. For each of a respective left and right ear of the user, an angle between the acoustic axis and the respective ear is determined. For each of the respective left and right ear of the user, a virtual speaker position, of a virtual speaker array, is determined, the virtual speaker position collinear with the source location and with a position of the respective ear. The virtual speaker array includes a plurality of virtual speaker positions, each virtual speaker position of the plurality located on the surface of a sphere concentric with the user's head, the sphere having a first radius. For each of the respective left and right ear of the user, a head-related transfer function (HRTF) corresponding to the virtual speaker position and to the respective ear is determined; a source radiation filter is determined based on the determined angle; the audio signal is processed to generate an output audio signal for the respective ear; and the output audio signal is presented to the respective ear of the user via one or more speakers associated with the wearable head device. Processing the audio signal includes applying the HRTF and the source radiation filter to the audio signal. ## Claims ### Claim 1 A method of presenting an audio signal to a user of a wearable head device, the method comprising: identifying a source location corresponding to the audio signal; determining an acoustic axis corresponding to the audio signal; for each of a respective left and right ear of the user: determining an angle between the acoustic axis and the respective ear; determining, of a virtual speaker array, a virtual speaker position collinear with the source location and a position of the respective ear, wherein the virtual speaker array comprises a plurality of virtual speaker positions, each virtual speaker position of the plurality of virtual speaker positions located on the surface of a sphere concentric with the user's head, the sphere having a first radius; determining a head-related transfer function (HRTF) corresponding to the virtual speaker position and to the respective ear; determining a source radiation filter based on the determined angle; processing the audio signal to generate an output audio signal for the respective ear, wherein processing the audio signal comprises applying the HRTF and the source radiation filter to the audio signal; attenuating the audio signal based on a distance between the source location and the respective ear wherein the distance is clamped at a minimum value; and presenting the output audio signal to the respective ear of the user via one or more speakers associated with the wearable head device. ### Claim 2 (depends on 1) The method of claim 1, wherein the source location is separated from a center of the user's head by a distance less than the first radius. ### Claim 3 (depends on 1) The method of claim 1, wherein the source location is separated from a center of the user's head by a distance greater than the first radius. ### Claim 4 (depends on 1) The method of claim 1, wherein the source location is separated from a center of the user's head by a distance equal to the first radius. ### Claim 5 (depends on 1) The method of claim 1, wherein processing the audio signal further comprises applying an interaural time difference to the audio signal. ### Claim 6 (depends on 1) The method of claim 1, wherein determining the HRTF corresponding to the virtual speaker position comprises selecting the HRTF from a plurality of HRTFs, wherein each HRTF of the plurality of HRTFs describes a relationship between a listener and an audio source separated from the listener by a distance substantially equal to the first radius. ### Claim 7 (depends on 1) The method of claim 1, wherein a distance from the source location to the center of the user's head is less than a radius of the user's head. ### Claim 8 (depends on 1) The method of claim 1, wherein a distance from the source location to the center of the user's head is greater than a radius of the user's head. ### Claim 9 (depends on 1) The method of claim 1, wherein a distance from the source location to the center of the user's head is substantially equal to a radius of the user's head. ### Claim 10 (depends on 1) The method of claim 1, wherein the angle comprises one or more of an azimuth and an elevation angle. ### Claim 11 (depends on 1) The method of claim 1, wherein the wearable head device comprises the one or more speakers. ### Claim 12 (depends on 1) The method of claim 1, wherein the wearable head device does not comprise the one or more speakers. ### Claim 13 (depends on 1) The method of claim 1, wherein the one or more speakers are associated with headphones worn by the user. ### Claim 14 A system comprising: a wearable head device; one or more speakers; and one or more processors configured to perform a method comprising: identifying a source location corresponding to an audio signal; determining an acoustic axis corresponding to the audio signal; for each of a respective left and right ear of a user of the wearable head device: determining an angle between the acoustic axis and the respective ear; determining, of a virtual speaker array, a virtual speaker position collinear with the source location and a position of the respective ear, wherein the virtual speaker array comprises a plurality of virtual speaker positions, each virtual speaker position of the plurality of virtual speaker positions located on the surface of a sphere concentric with the user's head, the sphere having a first radius; determining a head-related transfer function (HRTF) corresponding to the virtual speaker position and to the respective ear; determining a source radiation filter based on the determined angle; processing the audio signal to generate an output audio signal for the respective ear, wherein processing the audio signal comprises applying the HRTF and the source radiation filter to the audio signal; attenuating the audio signal based on a distance between the source location and the respective ear wherein the distance is clamped at a minimum value; and presenting the output audio signal to the respective ear of the user via the one or more speakers. ### Claim 15 (depends on 14) The system of claim 14, wherein the source location is separated from a center of the user's head by a distance less than the first radius. ### Claim 16 (depends on 14) The system of claim 14, wherein the source location is separated from a center of the user's head by a distance greater than the first radius. ### Claim 17 (depends on 14) The system of claim 14, wherein the source location is separated from a center of the user's head by a distance equal to the first radius. ### Claim 18 (depends on 14) The system of claim 14, wherein processing the audio signal further comprises applying an interaural time difference to the audio signal. ### Claim 19 (depends on 14) The system of claim 14, wherein determining the HRTF corresponding to the virtual speaker position comprises selecting the HRTF from a plurality of HRTFs, wherein each HRTF of the plurality of HRTFs describes a relationship between a listener and an audio source separated from the listener by a distance substantially equal to the first radius. ### Claim 20 (depends on 14) The system of claim 14, wherein a distance from the source location to the center of the user's head is less than a radius of the user's head. ### Claim 21 (depends on 14) The system of claim 14, wherein a distance from the source location to the center of the user's head is greater than a radius of the user's head. ### Claim 22 (depends on 14) The system of claim 14, wherein a distance from the source location to the center of the user's head is substantially equal to a radius of the user's head. ### Claim 23 (depends on 14) The system of claim 14, wherein the angle comprises one or more of an azimuth and an elevation angle. ### Claim 24 (depends on 14) The system of claim 14, wherein the wearable head device comprises the one or more speakers. ### Claim 25 (depends on 14) The system of claim 14, wherein the wearable head device does not comprise the one or more speakers. ### Claim 26 (depends on 14) The system of claim 14, wherein the one or more speakers are associated with headphones worn by the user. ### Claim 27 A non-transitory computer-readable medium storing instructions, which when executed by one or more processors cause the one or more processors to perform a method of presenting an audio signal to a user of a wearable head device, the method comprising: identifying a source location corresponding to the audio signal; determining an acoustic axis corresponding to the audio signal; for each of a respective left and right ear of the user: determining an angle between the acoustic axis and the respective ear; determining, of a virtual speaker array, a virtual speaker position collinear with the source location and a position of the respective ear, wherein the virtual speaker array comprises a plurality of virtual speaker positions, each virtual speaker position of the plurality of virtual speaker positions located on the surface of a sphere concentric with the user's head, the sphere having a first radius; determining a head-related transfer function (HRTF) corresponding to the virtual speaker position and to the respective ear; determining a source radiation filter based on the determined angle; processing the audio signal to generate an output audio signal for the respective ear, wherein processing the audio signal comprises applying the HRTF and the source radiation filter to the audio signal; attenuating the audio signal based on a distance between the source location and the respective ear wherein the distance is clamped at a minimum value; and presenting the output audio signal to the respective ear of the user via one or more speakers associated with the wearable head device. ### Claim 28 (depends on 27) The non-transitory computer-readable medium of claim 27, wherein the source location is separated from a center of the user's head by a distance less than the first radius. ### Claim 29 (depends on 27) The non-transitory computer-readable medium of claim 27, wherein the source location is separated from a center of the user's head by a distance greater than the first radius. ### Claim 30 (depends on 27) The non-transitory computer-readable medium of claim 27, wherein the source location is separated from a center of the user's head by a distance equal to the first radius. ### Claim 31 (depends on 27) The non-transitory computer-readable medium of claim 27, wherein processing the audio signal further comprises applying an interaural time difference to the audio signal. ### Claim 32 (depends on 27) The non-transitory computer-readable medium of claim 27, wherein determining the HRTF corresponding to the virtual speaker position comprises selecting the HRTF from a plurality of HRTFs, wherein each HRTF of the plurality of HRTFs describes a relationship between a listener and an audio source separated from the listener by a distance substantially equal to the first radius. ### Claim 33 (depends on 27) The non-transitory computer-readable medium of claim 27, wherein a distance from the source location to the center of the user's head is less than a radius of the user's head. ### Claim 34 (depends on 27) The non-transitory computer-readable medium of claim 27, wherein a distance from the source location to the center of the user's head is greater than a radius of the user's head. ### Claim 35 (depends on 27) The non-transitory computer-readable medium of claim 27, wherein a distance from the source location to the center of the user's head is substantially equal to a radius of the user's head. ### Claim 36 (depends on 27) The non-transitory computer-readable medium of claim 27, wherein the angle comprises one or more of an azimuth and an elevation angle. ### Claim 37 (depends on 27) The non-transitory computer-readable medium of claim 27, wherein the wearable head device comprises the one or more speakers. ### Claim 38 (depends on 27) The non-transitory computer-readable medium of claim 27, wherein the wearable head device does not comprise the one or more speakers. ### Claim 39 (depends on 27) The non-transitory computer-readable medium of claim 27, wherein the one or more speakers are associated with headphones worn by the user.