Multichannel Noise Cancellation via Frequency Domain Spectrum Masking
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Solution Overview
Problem
Existing acoustic echo cancellation techniques struggle to effectively isolate desired speech from undesired speech and ambient noise, especially when the device does not control the loudspeaker, leading to attenuation of desired speech and inadequate noise cancellation.
Innovation Solution
The system employs frequency masking by dividing the frequency spectrum into bands, selecting specific reference signals for each band, and generating a combined reference signal to improve noise cancellation, thereby reducing the attenuation of desired speech and enhancing signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional acoustic echo cancellation techniques are used, then noise cancellation is performed, but desired speech is attenuated and noise cancellation is inadequate
Solution Approach 1:
The frequency spectrum is divided into multiple frequency bins, allowing the system to process different frequency components separately. This segmentation enables selective manipulation of reference signals for each frequency bin, improving the ability to cancel noise while preserving desired speech components across different frequency ranges.
Solution Approach 2:
The system applies frequency masking by selectively attenuating or removing specific frequency components from the reference signal based on their contribution to noise versus desired speech. This local quality adjustment allows targeted noise cancellation in specific frequency regions while preserving speech components in other regions, resolving the contradiction between noise removal and speech preservation.
2Object-affected harmful factors
If a single reference signal is used for noise cancellation, then the system is simple to operate, but noise cancellation effectiveness is limited and speech attenuation occurs
Solution Approach 1:
Instead of using a single reference signal across all frequencies, the system segments the reference signal processing into multiple frequency bins. Each frequency bin can have its own masking coefficients applied, allowing differentiated noise cancellation strategies for different frequency ranges while maintaining a unified processing framework.
Solution Approach 2:
The system dynamically adjusts the masking parameters (attenuation coefficients) for each frequency bin based on the spectral characteristics of the audio signal. By changing these parameters adaptively across different frequencies, the system achieves improved noise cancellation effectiveness without requiring fundamentally complex additional hardware or processing architecture.
Data Source
AI summary
A system configured to improve noise cancellation by using portions of multiple reference signals instead of using a complete reference signal. The system divides a frequency spectrum into frequency bands and selects a single reference signal from a group of potential reference signals for every frequency band. For example, a first reference signal is selected for a first frequency band while a second reference signal is selected for a second frequency band. The system may generate a combined reference signal using portions of each of the selected reference signals, such as a portion of the first reference signal corresponding to the first frequency band and a portion of the second reference signal corresponding to the second frequency band. Additionally or alternatively, the system may perform noise cancellation using each of the selected reference signals and filter the outputs based on the corresponding frequency band to generate combined audio output data.