Dereverberated Signal Phase Estimation Using Instantaneous Frequency
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Solution Overview
Problem
Existing methods for estimating dereverberated signals from reverberated acoustic signals are limited in accuracy and depend heavily on the quality of training databases and fail to account for non-linear amplitude and phase modulations, leading to suboptimal speech intelligibility and sound quality.
Innovation Solution
A method that estimates the instantaneous phase of a dereverberated signal by calculating short-term Fourier transforms, determining instantaneous frequencies, and integrating them over time, using a correction factor based on the reverberation time of the medium, and applying a reassigned vocoder algorithm to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If supervised methods with Kalman filter and training databases are used to estimate dereverberated signals, then speech intelligibility can be improved, but the method becomes highly dependent on training database quality and only handles linear modulations
Solution Approach 1:
The patent extracts and removes the dependency on training databases by formulating a blind dereverberation method that directly estimates instantaneous frequency and phase from the reverberated signal itself, eliminating the need for external training data while maintaining speech intelligibility improvement
Solution Approach 2:
The patent changes the mathematical model from linear modulation assumptions to a more general framework that handles non-linear amplitude and phase modulations by using instantaneous frequency estimation and phase recovery techniques, thereby expanding the method's applicability beyond linear cases
2Reliability
If Kalman filter methods are used for dereverberation, then linear amplitude and phase modulations can be corrected, but non-linear modulations remain unhandled
Solution Approach 1:
The patent introduces dynamic adaptation by estimating instantaneous frequency and phase parameters that can vary non-linearly over time, allowing the system to adapt to both linear and non-linear modulations rather than being constrained to fixed linear models
Solution Approach 2:
The patent performs preliminary estimation of instantaneous frequency and phase parameters from the reverberated signal before reconstructing the dereverberated signal, enabling the system to handle non-linear modulations that would otherwise require complex iterative approaches
Data Source
AI summary
A method for estimating an instantaneous phase of dereverberated acoustic signal, the method comprising the following steps: measurement of an acoustic signal reverberated by propagation in a medium, estimation of a one short-term Fourier transform of the reverberated acoustic signal with a window function, calculation of an instantaneous frequency of dereverberated signal from said short-term Fourier transform and from an influencing factor of the medium, said influencing factor being a function of a reverberation time of said medium, determination of an instantaneous phase of dereverberated signal by integrating the instantaneous frequency of dereverberated signal over time.