Sum-Difference Audio Arrays to Reduce Upmixing Interference
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Solution Overview
Problem
Existing audio playback systems face issues with creating additional input channels using static upmixers, leading to undesirable audio artifacts and interference patterns due to high correlation of left and right channel signals.
Innovation Solution
Generate a sum and difference input signal from the left and right channels, applying distinct array transfer functions to these signals to produce arrayed output signals for playback across multiple channels, reducing signal correlation and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If static upmixers are used to create additional input channels, then the number of playback channels can be increased, but undesirable audio artifacts and interference patterns occur due to high correlation of left and right channel signals
Solution Approach 1:
The patent transforms the correlated left and right channel signals by applying a mathematical transformation to create sum and difference signals. This parameter change in the signal domain decorrelates the inputs, allowing multiple playback channels to be driven without the interference patterns that plague static upmixing approaches.
Solution Approach 2:
The patent replaces the traditional static upmixer mechanism with a sum-difference signal processing approach. Instead of using complex mechanical or electronic mixing networks that inherently produce artifacts, the invention uses algebraic transformation (sum and difference operations) to achieve channel expansion with superior audio quality.
2Device complexity
If left and right channel signals are highly correlated, then simple upmixing can be used, but this results in interference patterns and poor psychoacoustic performance
Solution Approach 1:
The invention maintains relative simplicity while improving reliability by changing the parameter representation of the audio signals. By working in the sum-difference domain rather than the traditional left-right domain, the system achieves better psychoacoustic performance without introducing complex additional hardware or processing stages.
3Object-generated harmful factors
If array transfer functions are applied to sum and difference signals, then interference patterns are reduced, but additional signal processing complexity is introduced
Solution Approach 1:
The patent substitutes traditional complex interference-reduction techniques with a more elegant mathematical approach. By transforming to sum-difference signals and applying array transfer functions in this domain, the system achieves interference pattern reduction with processing complexity that is actually simpler than many conventional multi-channel upmixing methods.
Data Source
AI summary
In some embodiments, a method comprises receiving audio content comprising left input channel signals and right input channel signals, and generating first and second input signals from the left and right input channel signals. The first input signal is based on a sum of the left and right input channel signals, and the second input signal is based on a difference of the left and right input channel signals. An array transfer function is applied to the first and second input signals to produced audio output signals, which can be provided to a plurality of audio transducers on one or more playback devices.