Audio Signal Processing Apparatus for Virtual Surround Sound
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Solution Overview
Problem
Existing audio signal processing methods for creating a virtual surround sound experience often alter the original sound quality and are dependent on the location of speakers and room shape, failing to provide users with a customizable acoustic space.
Innovation Solution
An audio signal processing apparatus and method that divides multi-channel audio signals into frequency bands, calculates phase differences and level ratios, and adjusts these parameters to control sound image localization, allowing users to customize the acoustic space without degrading the original sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a surround speaker outputs a waved signal of a difference between right-channel and left-channel audio signals with reverb and delay, then Virtual Surround effect is obtained, but the sound quality deteriorates and becomes hazy
Solution Approach 1:
The audio signal processing apparatus segments the audio signal into multiple frequency bands (e.g., low, mid, high frequencies) and processes each band separately with different reverb and delay characteristics. This allows precise control over sound image positioning in different frequency ranges while maintaining original sound quality, avoiding the hazy effect caused by uniform processing of the entire signal spectrum.
Solution Approach 2:
Different reverb and delay parameters are applied to different frequency bands according to their specific characteristics. Low-frequency sounds receive different spatial processing compared to high-frequency sounds, creating locally optimized sound quality for each frequency range while achieving overall Virtual Surround effect.
2Adaptability or versatility
If sound image localization is controlled by adjusting level ratio and phase difference, then acoustic space can be customized, but the system complexity increases
Solution Approach 1:
The system controls sound image localization by adjusting key parameters (level ratio between channels and phase difference) rather than processing the entire signal waveform. By changing these fundamental parameters in the frequency domain, the system achieves flexible acoustic space customization with computationally efficient operations, avoiding the need for complex time-domain signal manipulation.
Solution Approach 2:
The patent replaces complex mechanical acoustic space adjustment (physical speaker movement or room modification) with electronic parameter adjustment in the signal processing domain. This substitution allows acoustic space customization through software-controlled level and phase parameters, significantly reducing system complexity while maintaining or enhancing functionality.
3Measurement precision
If Virtual Surround characteristics are adjusted according to speaker location and room shape, then sound image accuracy improves, but the system becomes dependent on specific listening conditions
Solution Approach 1:
The audio signal processing apparatus implements a universal sound image control system that can adapt to different listening conditions through parameter adjustment. By providing standardized controls for level ratio and phase difference that work across various speaker configurations and room environments, the system achieves both accurate sound image localization and independence from specific listening conditions, making it universally applicable.
Data Source
AI summary
An audio signal processing apparatus includes: a division section that divides at least two or more channel audio signals into components in a plurality of frequency bands; a phase difference calculation section that calculates a phase difference between the two or more channel audio signals at each the frequency band; a level ratio calculation section that calculates a level ratio between the two or more channel audio signals at each the frequency band; a sound image localization estimation section that estimates, based on the level ratio or the phase difference, sound image localization at each the frequency band; and a control section that controls the estimated sound image localization at each the frequency band by adjusting the level ratio or the phase difference.