Post-Processed Audio Gains for Stable Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing noise reduction methods in audio signal processing often introduce artifacts such as speech distortion and musical noise due to estimation errors and non-stationarity of noise, leading to spurious peaks in the spectral representation of the signal.
Innovation Solution
The method involves post-processing raw gains determined by input processing using delta gain smoothing and decision-directed gain smoothing techniques to stabilize the gain variations, thereby reducing musical noise artifacts and improving the quality of the output signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gain determination is applied to reduce noise in audio signals, then noise reduction is improved, but speech distortion and musical noise artifacts are introduced
Solution Approach 1:
The patent applies preliminary smoothing to the gain function before it is applied to the audio signal. By pre-processing the gain values to reduce rapid fluctuations and spurious peaks, the method prevents musical noise artifacts from being introduced in the first place, while still maintaining effective noise reduction
Solution Approach 2:
The patent introduces an intermediary smoothing operation between the gain determination and the actual signal processing. This intermediate step acts as a buffer that modifies the gain characteristics to eliminate harmful artifacts while preserving the beneficial noise reduction effects
2Reliability
If aggressive noise reduction is applied to remove undesired signals, then noise removal is improved, but speech distortion increases
Solution Approach 1:
The patent modifies the parameters of the gain function through smoothing operations. By changing the temporal and spectral characteristics of the gain values, the method achieves effective noise removal while preventing the gain variations that cause speech distortion
Data Source
AI summary
A method, an apparatus, and logic to post-process raw gains determined by input processing to generate post-processed gains, comprising using one or both of delta gain smoothing and decision-directed gain smoothing. The delta gain smoothing comprises applying a smoothing filter to the raw gain with a smoothing factor that depends on the gain delta: the absolute value of the difference between the raw gain for the current frame and the post-processed gain for a previous frame. The decision-directed gain smoothing comprises converting the raw gain to a signal-to-noise ratio, applying a smoothing filter with a smoothing factor to the signal-to-noise ratio to calculate a smoothed signal-to-noise ratio, and converting the smoothed signal-to-noise ratio to determine the second smoothed gain, with smoothing factor possibly dependent on the gain delta.