Near-Field Audio Rendering Using Virtual Speaker Arrays

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Solution Overview

Problem

Augmented and mixed reality systems face challenges in simulating near-field audio effects due to the computational expense of using head-related transfer functions (HRTFs) measured at a single distance, which are not suitable for near-field effects, and existing methods are inefficient for real-time audio rendering on mobile devices with limited processing power.

Innovation Solution

A computationally efficient method is employed to model near-field audio effects using far-field HRTFs by determining a virtual speaker array on a sphere centered at the user's head, applying head-related transfer functions and source radiation filters to process audio signals for each ear, and presenting them via wearable speakers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If HRTFs measured at a single distance in far-field are used, then the system complexity is reduced, but near-field audio effects cannot be accurately simulated

Engineering Contradiction:

Improvesystem complexityVSAvoidnear-field audio simulation accuracy

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent changes the parameter of HRTF measurement distance from a single far-field distance to multiple distances including near-field distances. By measuring HRTFs at different distances (e.g., 0.25m, 0.5m, 1m, 2m) and using distance-dependent HRTF selection, the system accurately simulates near-field audio effects while maintaining manageable complexity through systematic parameter variation.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent segments the audio rendering process by dividing the 3D space into near-field and far-field regions based on distance thresholds. Different HRTF sets are selected and applied according to the sound source distance, allowing accurate near-field simulation without applying complex processing to all sound sources, thus resolving the contradiction between accuracy and complexity.

Inventive Principle:

Principle #1Segmentation

2Manufacturing precision

If multiple HRTFs for different distances are used, then near-field audio effects are accurately simulated, but computational expense increases

Engineering Contradiction:

Improvenear-field audio simulation accuracyVSAvoidcomputational expense

Core Design Contradiction:

Manufacturing precisionVSPower

Solution Approach 1:

The patent applies partial action by selectively using multiple HRTF sets only when the sound source is in the near-field region. For far-field sources, a single HRTF set is used. This partial application of complex processing only where needed (near-field) achieves accurate near-field audio effects while avoiding excessive computational expense for all sound sources.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent implements dynamic HRTF selection based on the real-time distance between the sound source and the listener. The system dynamically switches between different HRTF sets as the sound source moves between near-field and far-field regions, allowing accurate near-field simulation when required while reducing computational load when sound sources are in the far-field.

Inventive Principle:

Principle #15Dynamics

3Manufacturing precision

If high number of HRTFs are used for real-time audio rendering, then near-field audio effects are accurately simulated, but processing speed decreases

Engineering Contradiction:

Improvenear-field audio effects accuracyVSAvoidreal-time processing speed

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

Inventive Principle:

Principle #16Partial or excessive action

4Quantity of substance

If HRTFs measured at far-field distance are used, then the database size is reduced, but near-field audio realism is compromised

Engineering Contradiction:

ImproveHRTF database sizeVSAvoidaudio realism

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250287173A1Near-field audio rendering

Publication Date: 2025.09.11 MAGIC LEAP INC

AI summary

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. 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. 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; 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 to the audio signal.