Diffusivity-Based Audio Gain Control for Background Noise Reduction
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Solution Overview
Problem
Conventional Automatic Gain Control (AGC) systems often amplify background noise instead of enhancing signals of interest, particularly in audio scenes with varying noise levels, leading to degraded audio quality.
Innovation Solution
A diffusivity-based sound processing system that measures the diffusivity of audio signals using a diffusivity measurement unit and a leveler unit, applying gain adjustments based on the diffusivity level to minimize variations and distinguish between directional and diffuse sounds, thereby enhancing the audio signal of interest.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If Automatic Gain Control (AGC) is used to amplify soft sound signals, then the level of soft sounds is improved, but background noise is also amplified leading to degraded audio quality
Solution Approach 1:
The patent applies different gain adjustments to different portions of the audio signal based on their spatial characteristics. Directional sounds (low diffusivity) receive amplification while diffuse background noise (high diffusivity) is excluded from gain changes, achieving local quality enhancement without uniform noise amplification
Solution Approach 2:
The system changes the parameter used for gain control from simple level detection to diffusivity measurement. By measuring the diffusivity parameter of the audio signal, the system can distinguish between directional target sounds and diffuse background noise, enabling selective amplification based on this physical parameter
2Object-affected harmful factors
If noise gating is used to exclude low level sounds from AGC gain changes, then background noise amplification is reduced, but soft directional sounds of interest are also excluded leading to loss of intelligibility
Solution Approach 1:
Instead of uniformly excluding all low-level sounds from gain changes, the system applies gain changes selectively based on the local spatial characteristic (diffusivity) of each sound portion. This allows soft directional sounds to receive amplification while diffuse noise is excluded, achieving local quality differentiation
Solution Approach 2:
The system changes the discrimination parameter from simple level thresholding to diffusivity measurement. This parameter change enables the system to distinguish between soft directional sounds (low diffusivity) and diffuse noise (high diffusivity), preventing loss of information while reducing noise amplification
3Object-affected harmful factors
If general noise gating based on level comparison is used, then some background noise is excluded, but it is difficult to distinguish soft sounds of interest from background noise leading to failed amplification
Solution Approach 1:
The system changes the detection parameter from simple amplitude level to diffusivity measurement. This parameter change fundamentally improves the ability to distinguish between target sounds and background noise, as diffusivity captures the spatial distribution characteristic that differs between directional and diffuse sounds regardless of their amplitude
4Illumination intensity
If traditional noise gating systems amplify sounds above expected background noise level, then some signals are enhanced, but background noise above the expected level is also amplified degrading audio quality
Solution Approach 1:
The system applies gain changes based on local spatial characteristics rather than uniform level thresholds. Directional sounds receive amplification while diffuse noise is excluded, achieving local quality enhancement that prevents noise degradation even when noise levels exceed expected thresholds
Data Source
AI summary
A sound processing system operative to measure the level of diffusivity of the sounds present in the input sound signal. The system includes a plurality of input channels for receiving audio signals from an audio scene, the audio scene comprising at least one target sound in the presence of background noise. A diffusivity measurement unit is included so as to be operably coupled to the plurality of input channels to receive the audio signals therefrom and measure a level of diffusivity of the sounds present therein. A leveler unit is operably coupled to the plurality of input channels for receiving the audio signals therefrom and for applying a gain to the audio signals to minimize variations in the audio signal levels. A controller is operably coupled to the diffusivity measurement unit and the leveler unit to control the gain applied to the audio signals by the leveler unit based on the level of diffusivity of the sounds present therein.