PSAP Noise Suppression via Sub-band Gain Control
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Solution Overview
Problem
Personal Sound Amplification Products (PSAPs) face challenges in noise suppression, particularly with wind noise, as traditional methods fail to effectively reduce random noise with no fixed phase, leading to interference with speech intelligibility and increased costs due to structural adjustments or high latency from noise reduction modules.
Innovation Solution
A noise suppression method that estimates external noise in real-time, analyzes noise distribution and speech presence probabilities in sub-bands, and determines gains to control noise suppression in PSAPs, combining hardware and software paths to achieve low latency and effective noise reduction without introducing a noise reduction module into the hardware path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional noise reduction modules are introduced into the hardware path, then noise suppression effect is improved, but processing latency increases and device complexity increases
Solution Approach 1:
The patent replaces traditional hardware-based noise reduction modules with a software-based processing approach. The environmental audio signal is processed through filter banks and spectral analysis in the digital domain, where noise suppression is achieved by manipulating frequency components rather than using hardware filtering. This substitution enables flexible noise reduction without the latency and complexity constraints of hardware implementations.
Solution Approach 2:
The audio signal is divided into multiple frequency sub-bands using filter banks. Each sub-band can be independently analyzed and processed to suppress noise while preserving speech components. This segmentation allows selective noise reduction in specific frequency ranges without affecting the entire audio spectrum, thereby improving noise suppression effectiveness while maintaining low latency through parallel processing of sub-bands.
2Power
If ambient noise signal is amplified along with speech signal, then overall audio amplification is improved, but speech intelligibility deteriorates due to noise interference
Solution Approach 1:
The patent applies different processing characteristics to different frequency sub-bands. Speech frequency ranges are identified and given higher gain while noise-dominated sub-bands receive lower gain or noise suppression processing. This local differentiation allows the system to amplify speech components selectively while suppressing noise in other frequency regions, thereby maintaining speech intelligibility during amplification.
Solution Approach 2:
The system performs spectral analysis of the environmental audio signal to identify speech and noise components in different sub-bands. Based on this analysis, adaptive gain control is applied where speech components are amplified and noise components are suppressed. This feedback mechanism ensures that amplification enhances speech intelligibility rather than merely increasing overall volume including noise.
3Object-affected harmful factors
If noise suppression processing is applied, then noise interference is reduced, but processing complexity and cost increase due to structural adjustments
Solution Approach 1:
The patent implements a multi-functional signal processing framework where the same filter bank and spectral analysis structure serves multiple purposes: noise suppression, speech enhancement, and audio routing. By making the processing chain universal, the system achieves effective noise suppression without requiring separate dedicated hardware modules for each function, thereby reducing overall device complexity and cost.
Solution Approach 2:
The system uses software-based filter banks and spectral processing algorithms that can be implemented as programmable code rather than fixed hardware circuits. This software copying approach allows the noise suppression functionality to be replicated and adjusted through code rather than requiring physical structural adjustments, reducing manufacturing complexity and enabling flexible adaptation to different noise conditions.
Data Source
AI summary
In certain aspects, a noise suppression method and system for a personal sound amplification product (PSAP) are disclosed. An environmental audio signal acquired through one or more microphones is processed to generate a set of first sub-band signals in a set of first sub-bands. The environmental audio signal is also processed to generate a set of second sub-band signals in a set of second sub-bands. A set of first gains for the set of first sub-band signals in the set of first sub-bands is determined based on the set of second sub-band signals in the set of second sub-bands. The set of first sub-band signals is processed based on the set of first gains to generate a noise-suppressed audio signal.