Low-Frequency Interaural Coherence Control in Audio Reverberators

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional audio systems, especially those used in virtual reality and augmented reality, struggle to maintain high interaural coherence at low frequencies, leading to unnatural sound experiences due to destructive and constructive interferences caused by frequency-dependent matrices in artificial reverberators.

Innovation Solution

A system comprising a reverberator and a low-frequency interaural coherence control system, which includes comb filters, high-pass filters, all-pass filters, and a shared low-frequency section, is used to manage signal coherence, ensuring high coherence at low frequencies and low coherence at mid and high frequencies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a frequency dependent matrix is used in artificial reverberators, then spatial effects and realism are improved, but interaural coherence at low frequencies deteriorates due to destructive and constructive interferences

Engineering Contradiction:

Improvespatial effectsVSAvoidinteraural coherence

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The audio signal is segmented into different frequency bands (low-frequency and mid/high-frequency components). The low-frequency component is processed separately to maintain interaural coherence, while the mid/high-frequency component is processed to provide spatial effects. This segmentation allows independent optimization of coherence and spatial realism for different frequency ranges.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different quality characteristics are applied to different frequency bands. The low-frequency band is given high interaural coherence for realism, while the mid/high-frequency band is given spatial effects through the frequency dependent matrix. This local quality approach resolves the contradiction by allowing each frequency band to have optimized properties suitable for its perceptual characteristics.

Inventive Principle:

Principle #3Local quality

2Reliability

If high interaural coherence is maintained at low frequencies, then realism and immersion are improved, but system complexity increases due to additional signal processing sections

Engineering Contradiction:

ImproverealismVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The reverberator is segmented into distinct functional sections: a low-frequency section that maintains high interaural coherence and a mid/high-frequency section that provides spatial effects. This segmentation allows the system to achieve realism without requiring the entire system to be overly complex, as each section has a specific, optimized function.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically routes different frequency components to different processing paths based on their characteristics. Low-frequency components are routed to the coherence-preserving path, while mid/high-frequency components are routed to the spatial effects path. This dynamic approach allows the system to maintain realism while managing complexity through adaptive signal routing.

Inventive Principle:

Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enhances the realism of audio experiences by maintaining high interaural coherence at low frequencies, thereby improving the immersion and authenticity of virtual environments.

Implementation Method 1

The reverberator may include two sets of comb filters, one for a left ear output signal and one for a right ear output signal

Methodology Applied

Scientific EffectComb filtering:

Implementation Method 2

The plurality of filters may include one or more high-pass filters

Methodology Applied

Scientific EffectHigh-pass filtering: Filter (electronic)

Implementation Method 3

The plurality of filters may include one or more all-pass filters

Methodology Applied

Scientific EffectAll-pass filtering: Filter (electronic)

Implementation Method 4

A section may also include a shared low-frequency section

Methodology Applied

Scientific EffectLow-pass filtering: Filter (electronic)

Data Source

PatentUS11252528B2Low-frequency interchannel coherence control

Publication Date: 2022.02.15 MAGIC LEAP INC

AI summary

A system and method for providing low interaural coherence at low frequencies is disclosed. In some embodiments, the system may include a reverberator and a low-frequency interaural coherence control system. The reverberator may include two sets of comb filters, one for the left ear output signal and one for the right ear output signal. The low-frequency interaural coherence control system can include a plurality of sections, each section can be configured to control a certain frequency range of the signals that propagate through the given section. The sections may include a left high-frequency section for the left ear output signal and a right high-frequency section for the right ear output signal. The sections may also include a shared low-frequency section that can output signals to be combined by combiners of the left and right high-frequency sections.