# US 11,451,907 B2 · Techniques combining plural head-related transfer function (HRTF) spheres to place audio objects

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- Number: US 11,451,907 B2
- Document ID: US11451907B2
- Status: Granted
- Kind: B2
- Application number: 16/424,983
- Filed: 2019-05-29
- Published: 2020-12-03
- Granted: 2022-09-20
- Earliest claimed: 2019-05-29
- Assignees: Sony Corporation
- Applicants: Sony Corporation
- Inventors: James R. Milne; Gregory Peter Carlsson
- Web page: https://patentgrep.com/patent/US11451907B2

## CPC

- 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)}
- H04R 1/1008: {Earpieces of the supra-aural or circum-aural type}
- H04R 5/027: Spatial or constructional arrangements of microphones, e.g. in dummy heads
- H04R 5/033: Headphones for stereophonic communication {(details thereof, e.g. relating to batteries, cables or control elements H04R1/10)}
- H04R 29/002: {Loudspeaker arrays}
- H04S 7/301: {Automatic calibration of stereophonic sound system, e.g. with test microphone}
- H04S 7/302: {Electronic adaptation of stereophonic sound system to listener position or orientation (H04S7/301 takes precedence)}
- H04S 7/304: {For headphones}
- G02B 27/017: {Head mounted}
- G06F 3/012: {Head tracking input arrangements}
- H04N 21/25816: {involving client authentication (restricting access to computer systems by authenticating users using a predetermined code G06F21/33; cryptographic authentication protocols H04L9/32; networks authentication protocols H04L63/08; authentication in wireless network security H04W12/06)}
- H04N 21/6547: comprising parameters, e.g. for client setup
- 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]
- 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)
- H04S: STEREOPHONIC SYSTEMS
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

Concentric rings of speakers in a room are activated in sequence to emit test sounds that are picked up by microphones placed in the ears of a listener in the middle of the room. The output of the microphones is used to generate plural HRTF spheres that are concentric, and that can be convolved with each other to render a multi-distance HRTF filter that can be configured to “move” the perceived distance and bearing of audio objects “inside” the outer sphere as desired, without being restricted to placing the audio objects at the outer edges of a single sphere. Any desired placement of an audio object between spheres is done by interpolating between respective coefficients of the closest spheres.

## Claims

### Claim 1

A system comprising:
at least one processor configured with instructions to:
access at least first and second sets of head related transfer functions (HRTF) associated with respective first and second distances from a location, the first distance being shorter than the second distance;
identify a demanded distance of at least one audio object;
select at least a first HRTF from the first set of HRTFs based at least in part on the demanded distance being closer to the first distance than to the second distance;
subtract from the first HRTF a headphone HRTF derived using at least one speaker in a headphone and at least one microphone in the headphone to render a modified first HRTF, the headphone HRTF related to acoustics of the headphone itself; and
process the audio object using the modified first HRTF to render the audio object;
detect sound emitted by the at least one speaker using plural microphones in a first set of microphones located at a first radial distance from the at least one speaker;
use signals from the plural microphones in the first set of microphones to establish the first set of HRTF s;
detect sound emitted by the at least one speaker using plural microphones in a second set of microphones located at a second radial distance from the at least one speaker; and
use signals from the plural microphones in the second set of microphones to establish the second set of HRTFs.

### Claim 2 (depends on 1)

The system of claim 1, wherein the first set of HRTF is associated with a first sphere having a radius of the first distance and the second set of HRTF is associated with a second sphere having a radius of the second distance.

### Claim 3 (depends on 2)

The system of claim 2, comprising a third set of HRTF associated with a third sphere having a radius equal to a third distance shorter than the first distance, and the instructions are executable to:
responsive to identifying the demanded distance being between the first and third distances, process the audio object using an interpolation of at least the first HRTF and at least one HRTF from the third set of HRTF.

### Claim 4 (depends on 1)

The system of claim 1, wherein the instructions are executable to:
select at least the first HRTF from the first set of HRTF based at least in part on a demanded bearing of the audio object.

### Claim 5 (depends on 1)

The system of claim 1, wherein the first HRTF and the headphone HRTF are both established based on input from one or more microphones.

### Claim 6 (depends on 1)

The system of claim 1, wherein the at least one processor is configured with instructions to:
use input from at least one microphone to measure the acoustics of the headphone itself.

### Claim 7 (depends on 1)

The system of claim 1, wherein the processor is configured with instructions to:
with the head of a wearer in a first orientation and HRTF measurement components at a first radial distance from the wearer, establish the first set of HRTFs; and
with the head of a wearer in the first orientation and HRTF measurement components at a second radial distance from the wearer, establish the second set of HRTF.

### Claim 8

A method, comprising:
establishing plural sets of head related transfer functions (HRTF) associated with respective plural radial distances from a headphones and outside the headphones;
providing the plural sets of HRTF at least one of which is modified by a headphone HRTF derived using at least one speaker in the headphones and at least one microphone in the headphones to render audio objects, the headphone HRTF related to how a user hears with the headphones themselves;
wherein the establishing comprises:
energizing at least one speaker at the origin;
detecting sound emitted by the speaker using plural microphones in a first set of microphones located at the first radial distance from the at least one speaker;
using signals from the microphones in the first set of microphones located at the first radial distance to establish a first of the sets of HRTF;
moving the first set of microphones to the second radial distance;
detecting sound emitted by the first set of microphones located at the second radial distance from the at least one speaker; and
using signals from the first set of microphones located at the second radial distance to establish a second of the sets of HRTF.

### Claim 9 (depends on 8)

The method of claim 8, wherein the establishing comprises:
energizing speakers in a first set of speakers located at the first radial distance from at least one microphone;
using signals from the microphone generated in response to energizing the speakers in the first set of speakers to establish a first of the sets of HRTF;
energizing speakers in a second set of speakers located at the second radial distance from the microphone; and
using signals from the microphone generated in response to energizing the speakers in the second set of speakers to establish a second of the sets of HRTF.

### Claim 10 (depends on 9)

The method of claim 9, wherein speakers in the first set of speakers are not radially aligned with respective speakers in the second set of speakers.

### Claim 11 (depends on 9)

The method of claim 9, wherein speakers in the first set of speakers are arranged in a sphere.

### Claim 12 (depends on 8)

The method of claim 8, wherein the establishing comprises:
energizing speakers in a first set of speakers located at the first radial distance from at least one microphone;
using signals from the microphone generated in response to energizing the speakers in the first set of speakers at the first radial distance to establish a first of the sets of HRTF;
moving the speakers in the first set of speakers to a second radial distance from the microphone;
energizing the speakers in the first set of speakers located at the second radial distance from the microphone; and
using signals from the microphone generated in response to energizing the speakers at the second radial distance to establish a second of the sets of HRTF.

### Claim 13 (depends on 8)

The method of claim 8, wherein the establishing comprises:
energizing at least one speaker at the origin;
detecting sound emitted by the speaker using plural microphones in a first set of microphones located at the first radial distance from the at least one speaker;
using signals from the microphones in the first set of microphones to establish a first of the sets of HRTF;
detecting sound emitted by the speaker using plural microphones in a second set of microphones located at the second radial distance from the at least one speaker; and
using signals from the microphones in the second set of microphones to establish a second of the sets of HRTF.

### Claim 14 (depends on 8)

The method of claim 8, comprising:
prompting a wearer of the headphones to orient his head at a first orientation, with coefficients of a first FIR filter being determined at the first orientation, and then prompting the wearer to reorient his head at a second orientation, with coefficients of a second filter being determined at the second orientation.

### Claim 15

A method, comprising:
establishing plural sets of head related transfer functions (HRTF) associated with respective plural radial distances from a headphones and outside the headphones;
providing the plural sets of HRTF at least one of which is modified by a headphone HRTF derived using at least one speaker in the headphones and at least one microphone in the headphones to render audio objects, the headphone HRTF related to how a user hears with the headphones themselves;
with the head of a wearer in a first orientation and HRTF measurement components at a first radial distance from the wearer, establishing a first set of HRTF;
moving the HRTF measurement components to a second radial distance from the wearer; and
with the head of a wearer in the first orientation and HRTF measurement components at the second radial distance from the wearer, establishing a second set of HRTF.