Adaptive Electroacoustic Channel Equalization for Noise And Speech Clarity
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Solution Overview
Problem
Existing audio signal processing technologies face challenges in effectively reducing external noise and improving speech clarity in noisy environments, particularly in portable devices, due to variability in the electroacoustic channel transfer function caused by changes in device position and user attributes.
Innovation Solution
The method involves establishing an adaptive transfer function estimate of the electroacoustic channel using a combination of transfer functions, derived from error minimization techniques, and applying filters to invert this estimate to cancel noise and equalize audio signals, utilizing a combination of IIR and FIR filters to account for temporal variations and frequency ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adaptive transfer function estimation is implemented to handle temporal variations, then noise reduction effectiveness is improved, but device complexity increases
Solution Approach 1:
The patent implements dynamic adaptation by continuously updating the transfer function estimate in response to temporal variations in the electroacoustic channel. The system transitions from static to dynamic operation by adapting filter coefficients in real-time based on changing acoustic conditions, thereby maintaining noise reduction effectiveness across varying environments.
Solution Approach 2:
The patent segments the complex adaptive filtering problem into manageable components by using a combination of IIR and FIR filters in cascade configuration. This segmentation allows the system to handle different aspects of the transfer function estimation separately, reducing overall computational complexity while maintaining effectiveness.
2Manufacturing precision
If multiple filter types (IIR and FIR) are used in cascade for equalization, then sound quality is improved, but device complexity increases
Solution Approach 1:
The patent employs a composite filtering approach by combining IIR and FIR filter types in cascade configuration. This composite structure leverages the strengths of both filter types - IIR filters provide efficient low-frequency response while FIR filters handle high-frequency characteristics, achieving superior overall sound quality that neither filter type could achieve alone.
Solution Approach 2:
The filter cascade structure serves multiple functions simultaneously: noise cancellation, equalization, and temporal variation compensation. By designing the filter system to perform multiple functions through a unified architecture, the patent avoids the need for separate dedicated systems for each function, thereby managing complexity while achieving comprehensive sound quality improvement.
3Measurement precision
If error minimization techniques are employed for filter optimization, then speech clarity is improved, but computational requirements increase
Solution Approach 1:
The patent implements error minimization through feedback mechanisms where the system continuously monitors the output and adjusts filter coefficients to minimize the difference between desired and actual responses. This feedback-driven optimization improves speech clarity by adapting to minimize distortion and noise, while the efficient feedback algorithm manages computational requirements.
Data Source
AI summary
An electroacoustic channel soundfield is altered. An audio signal is applied by an electromechanical transducer to an acoustic space, causing air pressure changes therein. Another audio signal is obtained by a second electromechanical transducer, responsive to air pressure changes in the acoustic space. A transfer function estimate of the electroacoustic channel is established, responsive to the second audio signal and part of the first audio signal. The transfer function estimate is derived to be adaptive to temporal variations in the electroacoustic channel transfer function. Filters are obtained with transfer functions based on the transfer function estimate. Part of the first audio signal is filtered therewith.