Audio Spatialization Emphasis Filtering for Artifact-Free Gain Shifts

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Solution Overview

Problem

Existing audio signal processing systems in virtual environments face challenges in accurately presenting soundscapes while minimizing sonic artifacts and maintaining computational efficiency, particularly for mobile devices.

Innovation Solution

Implementing pre-emphasis and de-emphasis filters in audio spatialization systems to adjust gain values smoothly over time, reducing sonic artifacts by filtering low and high frequency energy, respectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If rapid changes are made to audio signals to reflect changing positions and orientations of objects and user, then the soundscape accurately reflects the virtual environment, but sonic artifacts such as clicking sounds occur that compromise immersiveness

Engineering Contradiction:
Improveaccuracy of soundscape reflectionVSAvoidsonic artifacts
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The system applies pre-emphasis filtering before gain adjustment to pre-condition the audio signal. This preliminary action modifies the signal characteristics in advance, making subsequent gain changes smoother and reducing the occurrence of sonic artifacts when object or user positions change rapidly.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system changes the frequency characteristics of the audio signal by applying pre-emphasis and de-emphasis filters. This parameter change in the signal domain allows for smoother gain transitions and reduces high-frequency components that would otherwise manifest as audible clicking artifacts during rapid spatial updates.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If techniques are applied to reduce sonic artifacts, then audio quality improves, but computational cost increases particularly for mobile devices

Engineering Contradiction:
Improvesonic artifactsVSAvoidcomputational energy
Core Design Contradiction:
Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The system applies simple first-order pre-emphasis and de-emphasis filters that modify signal parameters with minimal computational overhead. These filters use basic mathematical operations that are computationally efficient and well-suited for mobile devices, unlike more complex artifact reduction techniques.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The system uses computationally inexpensive filtering operations that can be applied rapidly and discarded each frame. These simple filter operations require minimal processing resources compared to sophisticated artifact reduction algorithms, making them ideal for real-time mobile audio processing.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Measurement precision

If gain values are adjusted rapidly to reflect changing spatial positions, then audio spatialization accuracy improves, but sonic artifacts occur due to abrupt gain changes

Engineering Contradiction:
Improvespatialization accuracyVSAvoidclicking sounds
Core Design Contradiction:
Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The pre-emphasis filter is applied before gain adjustment to pre-condition the signal. This preliminary filtering action shapes the signal spectrum in advance, reducing high-frequency content that would be accentuated by rapid gain changes and causing clicking artifacts.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system modifies the frequency domain parameters of the audio signal through pre-emphasis and de-emphasis filtering. This parameter transformation allows rapid gain adjustments to be made in the spatial domain while the frequency domain characteristics remain smooth, preventing audible artifacts.

Inventive Principle:
Principle #35Parameter changes

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

Enhances the realism and immersion of audio experiences by minimizing sonic artifacts and optimizing computational resources.

Implementation Method 1

applying a pre-emphasis filter to the first input audio signal comprises attenuating a low frequency component of the first input audio signal

Methodology Applied
Scientific EffectFrequency attenuation: Filter (electronic)

Implementation Method 2

applying a de-emphasis filter to the first audio signal comprises attenuating a high frequency component of the first audio signal

Methodology Applied
Scientific EffectFrequency attenuation: Filter (electronic)

Data Source

PatentEP3861763B1Emphasis for audio spatialization
Publication Date: 2025.11.26 MAGIC LEAP INC
  • EP3861763B1 patent drawingFigure 1A
  • EP3861763B1 patent drawingFigure 1B
  • EP3861763B1 patent drawingFigure 2A~2B

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 first input audio signal is received. The first input audio signal is processed to generate a first output audio signal. The first output audio signal is presented via one or more speakers associated with the wearable head device. Processing the first input audio signal comprises applying a pre-emphasis filter to the first input audio signal; adjusting a gain of the first input audio signal; and applying a de- emphasis filter to the first audio signal Applying the pre-emphasis filter to the first input audio signal comprises attenuating a low frequency component of the first input audio signal. Applying the de-emphasis filter to the first input audio signal comprises attenuating a high frequency component of the first input audio signal.