Stereo Signal Perceptual Width via Joint Mid-Side Decorrelation
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Solution Overview
Problem
Conventional methods for generating stereo signals for headphones result in in-head localization of sound sources due to psychoacoustic properties, leading to a disturbing spatial impression, and existing solutions are computationally complex or compromise audio quality.
Innovation Solution
The method involves decorrelating portions of the mid-signal and side-signal to create an enhanced side-signal, which is then combined with the mid-signal to produce a stereo output that enhances perceptual width without shifting sound sources, using a decorrelator and signal combiner to achieve out-of-head localization with low computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional filtering methods are applied to mid-signal and side-signal separately to increase out-of-head localization, then perceived spatial width is improved, but computational complexity increases unacceptably
Solution Approach 1:
The patent combines the filtering operations for mid-signal and side-signal into a single joint filtering process. Instead of applying separate filters to each signal component, the invention processes them together through a unified filter structure, reducing the total number of filtering operations and computational resources required while maintaining the spatial widening effect.
Solution Approach 2:
The patent employs a universal filter structure that handles both mid-signal and side-signal processing simultaneously. This multi-functional filter performs multiple tasks (filtering mid-signal, filtering side-signal, and managing their interaction) within a single computational framework, eliminating redundant operations and reducing overall complexity.
2Ease of operation
If head related transfer functions are used to simulate loudspeaker listening situation, then out-of-head localization is achieved, but computational resources required are excessive for portable devices
Solution Approach 1:
The patent extracts and implements only the essential spatial processing components needed for out-of-head localization, omitting the full complexity of head related transfer functions. By taking out only the critical filtering and decorrelation operations required for spatial perception, the system achieves the desired effect with significantly reduced computational requirements suitable for portable devices.
3Device complexity
If simple low-order filters are used to reduce computational complexity, then processing power is reduced, but the accuracy of simulating human body influence is compromised
Solution Approach 1:
The patent changes the parameters of the filtering operation to achieve an optimal balance between complexity and accuracy. By adjusting filter order, cutoff frequencies, and processing parameters, the system maintains sufficient simulation accuracy for human body influence while keeping computational complexity low enough for portable device implementation.
Data Source
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AI summary
A stereo signal with enhanced perceptual quality using a mid-signal and a side-signal, can be generated, when a enhanced side signal is created prior to the upmix of the stereo signal. A decorrelated representation of at least a portion of the sum signal and/or a decorrelated representation of at least a portion of the side-signal is generated. The enhanced side-signal is generated combining a representation of the side-signal with the decorrelated representation of the portion of the mid signal, with the decorrelated representation of the side-signal and the decorrelated representation of the portion of the mid-signal or with the portion of the mid-signal and the decorrelated representation of the portion of the side-signal. The stereo signal with enhanced perceptual quality is created using a representation of the mid-signal and the enhanced side-signal.