Binaural Audio Rendering Filter for In-Head Sound Simulation

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Solution Overview

Problem

Existing binaural sound synthesis methods fail to accurately simulate sound sources close to the listener, leading to undesirable audio signals and discomfort due to prominent head shadowing effects, especially when the sound source is between the listener's ears.

Innovation Solution

A method and device for rendering binaural audio signals that filter sound programs to produce low-frequency and high-frequency portions, panning the high-frequency portions according to the sound location between the earpieces to create a realistic in-head audio experience, while maintaining a constant low-frequency portion to prevent occlusion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If binaural filters are used to simulate sound sources close to the listener, then the position accuracy of the sound source is improved, but head shadowing effects become prominent causing discomfort and occlusion sensation

Engineering Contradiction:

Improvesound source position accuracyVSAvoidhead shadowing effects

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The sound signal is segmented into different frequency components (low-frequency and high-frequency portions). The high-frequency portion is panned according to sound location while the low-frequency portion remains constant, preventing head shadowing effects while maintaining position accuracy for near-field sound sources

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different frequency components are treated differently based on their propagation characteristics. High-frequency signals are panned to create spatial position information, while low-frequency signals are kept constant to avoid occlusion, applying local quality adjustments to different parts of the sound spectrum

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If the sound source is placed between the listener's ears, then the spatial realism is improved, but the feeling of occlusion increases due to head shadowing

Engineering Contradiction:

Improvespatial realismVSAvoidocclusion sensation

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The audio signal is divided into low-frequency and high-frequency portions. The high-frequency portion is panned according to the sound location between the ears to create spatial realism, while the low-frequency portion remains constant to prevent occlusion sensation

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The panning parameter is applied selectively to different frequency components. High-frequency signals undergo panning transformation to achieve spatial positioning, while low-frequency signals maintain constant amplitude, changing the parameter application strategy based on frequency

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11812247B2System to move sound into and out of a listener's head using a virtual acoustic system

Publication Date: 2023.11.07 APPLE INC

AI summary

In a device or method for rendering a sound program for headphones, a location is received for placing the sound program with respect to first and second ear pieces. If the location is between the first ear piece and the second ear piece, the sound program is filtered to produce low-frequency and high-frequency portions. The high-frequency portion is panned according to the location to produce first and second high-frequency signals. The low-frequency portion and the first high-frequency signal are combined to produce a first headphone driver signal to drive the first ear piece. A second headphone driver signal is similarly produced. The sound program may be a stereo sound program. The device or method may also provide for a location that is between the first ear piece and a near-field boundary. Other aspects are also described.