Speech Filter Tuning for Noisy Listening Without Digital Clipping
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Solution Overview
Problem
Existing methods for improving speech intelligibility in noisy environments face challenges in maintaining signal power and achieving optimal spectral adjustments, particularly when the signal is close to digital overload, and struggle to provide maximum desired effects in a controlled manner.
Innovation Solution
A device and method that use an adaptable filter system to optimize the signal-to-noise ratio of speech output by an electro-acoustical transducer, adjusting the spectral characteristics without increasing the overall signal level, and configuring the filter based on ambient noise and input signal spectra to enhance intelligibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the power of the speech signal is increased to improve intelligibility, then speech intelligibility is improved, but digital clipping and signal distortion occur when the signal is close to overload level
Solution Approach 1:
The patent changes the spectral parameters of the speech signal by emphasizing the second formant relative to the first formant. This spectral reshaping improves intelligibility without increasing overall signal power, thereby avoiding digital clipping and distortion that would result from simple power amplification.
2Loss of information
If the spectral characteristics are altered to improve intelligibility, then speech intelligibility is improved, but the ability to obtain maximum desired effect in a controlled manner is lost
Solution Approach 1:
The patent employs dynamic control of spectral characteristics by adaptively adjusting the emphasis on the second formant based on real-time analysis of the speech signal. This dynamic approach allows for controlled spectral shaping that maximizes intelligibility improvement while maintaining operational control, unlike static filtering methods.
Data Source
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AI summary
One aspect of the invention provides a method for enhancing speech output by an electro- acoustical transducer in a noisy listening environment. In some embodiments, this method includes: filtering an input audio signal x(t) using a filter H(z) to produce a filtered audio signal x(t) formula (I), wherein x(t) formula (I) - H(z)x(t); providing to an electro-acoustical transducer a signal corresponding to the filtered audio signal x(t) formula (I) to produce a sound wave corresponding to the filtered audio signal; and prior to filtering the audio signal using the filter, configuring the filter such that, with respect to one or more frequencies, the filtered audio signal has a higher signal level than the input audio signal, and such that the overall signal level of the filtered audio signal (sl f ) is substantially related to the overall signal level of the input signal (sl r ) such that si/ = sl / x c.