Spatial Audio Parameter Smoothing for Musical Noise Reduction
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Solution Overview
Problem
Existing spatial audio processing technologies face challenges in effectively smoothing temporal fluctuations in spatial audio parameters, leading to artifacts like 'musical noise' during sound reproduction, especially in dynamic sound scenes with multiple sources and reverberation.
Innovation Solution
The proposed solution involves an adaptive temporal smoothing method that analyzes the stability of direction-related parameters to determine the necessary smoothing coefficients, adjusting the amount of smoothing based on the direct-to-total energy ratio, thereby improving the quality of spatial sound reproduction by minimizing unnecessary smoothing when the energy ratio is consistently high.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If temporal smoothing is applied to spatial audio parameters, then musical noise artifacts are reduced, but the system response speed to sound field changes decreases
Solution Approach 1:
The patent implements dynamic adaptation of smoothing coefficients based on the estimated stability of spatial audio parameters. When parameters are stable, stronger smoothing is applied to reduce musical noise. When parameters change rapidly, smoothing is reduced or disabled to maintain fast response. This dynamic adjustment resolves the contradiction by making the smoothing strength variable rather than fixed.
Solution Approach 2:
The patent changes the smoothing coefficient parameter adaptively based on the stability assessment of spatial audio parameters. The smoothing coefficient is adjusted as a variable parameter rather than a fixed value, allowing the system to optimize between noise reduction and response speed by modifying this key parameter according to current acoustic conditions.
2Stability of the object's composition
If strong temporal smoothing is applied to spatial audio parameters, then parameter fluctuations are reduced, but accurate spatial perception during dynamic scenes deteriorates
Solution Approach 1:
The patent dynamically adjusts smoothing strength based on the stability of spatial parameters. When parameters are stable, strong smoothing is applied to reduce fluctuations. When parameters change rapidly indicating dynamic scenes, smoothing is reduced to preserve spatial accuracy. This resolves the contradiction by making smoothing adaptive rather than constant.
Solution Approach 2:
The patent uses feedback from stability estimation of spatial audio parameters to control the amount of smoothing applied. The system estimates parameter stability, uses this information to adjust smoothing coefficients, and applies the adapted smoothing to maintain both stability and accuracy. This closed-loop feedback mechanism resolves the contradiction between smoothing and accuracy.
3Object-affected harmful factors
If adaptive smoothing based on direction parameter stability is implemented, then musical noise is reduced, but computational complexity increases
Solution Approach 1:
The patent changes the smoothing coefficient based on parameter stability estimation, using a data-driven approach to adapt smoothing strength. This resolves the contradiction by using simple stability metrics to control complex smoothing behavior, reducing musical noise while managing computational load through efficient parameter adaptation.
Data Source
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AI summary
An apparatus for spatial audio signal processing, the apparatus comprising at least one processor and at least one memory including a computer program code. The at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to receive at least one audio signal (502), determine at least one spatial parameter (508) associated with the at least one audio signal (502), generate an adaptive smoothing parameter (706) based on the at least one spatial parameter (508), determine panning gains (708) for applying to a first part (704) of the at least one audio signals (502), apply the adaptive smoothing parameter (706) to the panning gains (708) to generate associated smoothed panning gains (710), and apply the smoothed panning gains (710) to the first part (704) of the at least one audio signal (502) to generate a positioned audio signal.