3D Audio Signal Processing Using Asymmetric Filtering

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing 2D audio recordings lack the directional audio signals necessary for 3D audio reproduction, leading to an unnatural or distorted spatial sound impression when played back using 3D audio systems, as they were not created with height considerations in mind.

Innovation Solution

A device that processes 2D audio signals using signal delays, frequency-dependent amplitude adjustments, and limited reverberation effects, along with asymmetrical processing, to generate the necessary directional audio signals for 3D audio reproduction, considering psychoacoustic effects to create a natural and undistorted 3D audio effect.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If directional audio signals for 3D audio reproduction are generated by adding hall effects to all directional audio signals, then a spatial sound image is created, but the sound becomes unnatural or distorted due to phase problems and frequency-dependent cancellations

Engineering Contradiction:

Improvespatial sound image creationVSAvoidsound naturalness

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent applies different processing to different directional audio signals based on their spatial characteristics. Front directional signals receive low-pass filtering while rear directional signals receive high-pass filtering, creating local quality differences that prevent phase problems and frequency-dependent cancellations while maintaining spatial sound image creation

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the frequency characteristics of different directional audio signals by applying frequency-dependent filtering. Front signals are low-pass filtered and rear signals are high-pass filtered, which transforms the parameter characteristics to avoid phase problems and maintain natural sound reproduction in 3D audio playback

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If 3D audio playback systems use 2D audio recordings without additional processing, then the system can operate with existing recordings, but the desired spatial 3D audio effect does not result

Engineering Contradiction:

Improvecompatibility with existing recordingsVSAvoidspatial 3D audio effect

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent transforms 2D audio recordings into 3D audio output by deriving missing directional audio signals through asymmetric filtering and processing. This dimensionality change allows existing 2D recordings to be played back on 3D audio systems with proper spatial effects, achieving both compatibility and spatial audio quality

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Ease of operation

If heavy reverberation is used to create spatial sound impression, then a three-dimensional effect is achieved, but phase problems occur leading to frequency-dependent cancellations and comb filter effects

Engineering Contradiction:

Improvethree-dimensional effectVSAvoidphase problems

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent applies different filtering characteristics to different spatial directions to avoid phase problems. Front directional signals are low-pass filtered while rear directional signals are high-pass filtered, creating local quality differences that prevent harmful phase interactions and frequency-dependent cancellations while maintaining the three-dimensional spatial effect

Inventive Principle:

Principle #3Local quality

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

The device effectively converts 2D audio signals into a convincing 3D audio experience by generating the required directional audio signals, avoiding phase problems and frequency-dependent cancellations, resulting in a more natural and immersive sound environment.

Implementation Method 1

Through a targeted use of signal delays, frequency-dependent amplitude adjustments and a limited use of reverberation effects in connection with a targeted asymmetrical processing, the desired spatial 3D audio effect is generated

Methodology Applied

Scientific EffectTime delay:

Implementation Method 2

Methodology Applied

Scientific EffectFrequency-dependent amplitude adjustment:

Implementation Method 3

Methodology Applied

Scientific EffectReverberation: Reverberation

Data Source

PatentEP2939445B1Production of 3D audio signals

Publication Date: 2019.11.13 SENNHEISER ELECTRONICS GMBH & CO KG

Figure 1~2
Figure 3
Figure 4

AI summary

A device which produces the necessary directional audio signals for a 3-dimensional audio playback and which in that case uses as input signals the available channels of an audio recording intended for 2-dimensional audio playback. By taking psychoacoustic effects into account the desired spatial 3D audio effect is produced by a targeted use of signal delays, frequency-dependent amplitude matchings and a limited use of reverberation effects in conjunction with a targetedly asymmetric processing.