Multi-Channel Comfort Noise Spatial Coherence
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Solution Overview
Problem
Existing comfort noise generation methods for multi-channel audio signals, such as stereo, often result in unpleasant effects for listeners, as they fail to accurately replicate the spatial characteristics of background noise, leading to perceived anomalies like a noise source located within the head.
Innovation Solution
The method determines the spatial coherence between audio signals on multiple channels and generates comfort noise that matches this coherence, using spectral and spatial shaping filters derived from the signal spectra and coherence functions, ensuring the comfort noise replicates the spatial characteristics of the original background noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If comfort noise is generated using conventional spectral shaping methods for multi-channel audio, then the spectral characteristics can be matched, but the spatial characteristics are not replicated accurately, causing unpleasant listener effects
Solution Approach 1:
The patent extends conventional spectral shaping by incorporating spatial dimension through coherence functions. Instead of only shaping noise in the frequency domain, the invention adds spatial correlation shaping using coherence between channels, thereby replicating both spectral and spatial characteristics of background noise to eliminate unpleasant effects like perceived noise sources inside the head.
2Ease of operation
If comfort noise is generated without considering spatial coherence, then the generation process is simpler, but the spatial characteristics of background noise are not replicated
Solution Approach 1:
The patent calculates coherence functions between audio channels in advance during periods when background noise is present. These pre-calculated coherence values are then stored and reused during comfort noise generation, avoiding complex real-time spatial calculations while ensuring accurate spatial characteristic replication.
3Object-affected harmful factors
If spectral and spatial characteristics are both replicated in comfort noise, then listener experience is improved, but the complexity of the generation process increases
Solution Approach 1:
The patent divides the comfort noise generation process into separate spectral shaping and spatial shaping stages. Spectral characteristics are shaped using conventional filtering methods, while spatial characteristics are shaped separately using pre-calculated coherence functions. This segmentation allows each aspect to be handled independently, reducing overall system complexity while achieving both spectral and spatial accuracy.
Data Source
AI summary
Apparatuses, arrangements and methods therein for generation of comfort noise are disclosed. In short, the solution relates to exploiting the spatial coherence of multiple input audio channels in order to generate high quality multi channel comfort noise.