System for improving speech intelligibility through high frequency compression
First Claim
Patent Images
1. A speech system that improves the intelligibility and quality of a processed speech, comprising:
- a frequency transformer device that converts a speech signal into a spectrum of frequencies;
a spectral compressor device electrically coupled to the frequency transformer that compresses a pre-selected high frequency band of the speech signal and maps the compressed high frequency band to a lower band limited frequency range; and
a gain controller device that applies a variable gain to the compressed high frequency band in relation to a background noise level present in the speech signal, where the gain controller selects a level for the variable gain based on a slope of a noise floor present in the compressed high frequency band of the speech signal and a slope of a noise floor present in an uncompressed frequency portion of the speech signal.
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Abstract
A speech enhancement system that improves the intelligibility and the perceived quality of processed speech includes a frequency transformer and a spectral compressor. The frequency transformer converts speech signals from the time domain to the frequency domain. The spectral compressor compresses a pre-selected portion of the high frequency band and maps the compressed high frequency band to a lower band limited frequency range.
115 Citations
27 Claims
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1. A speech system that improves the intelligibility and quality of a processed speech, comprising:
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a frequency transformer device that converts a speech signal into a spectrum of frequencies; a spectral compressor device electrically coupled to the frequency transformer that compresses a pre-selected high frequency band of the speech signal and maps the compressed high frequency band to a lower band limited frequency range; and a gain controller device that applies a variable gain to the compressed high frequency band in relation to a background noise level present in the speech signal, where the gain controller selects a level for the variable gain based on a slope of a noise floor present in the compressed high frequency band of the speech signal and a slope of a noise floor present in an uncompressed frequency portion of the speech signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A speech system that improves the intelligibility of a processed speech, comprising:
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a frequency transformer device that converts a speech signal into the frequency domain; a spectral compressor device coupled to the frequency transformer that compresses a pre-selected high frequency band of the speech signal and maps the compressed high frequency band to a lower frequency band; a noise detector device that detects and estimates a level of noise present; and a gain controller device that adjusts a gain of the compressed high frequency band proportionally to a changing level of an independent and extraneous signal, where the gain controller amplifies a portion of the speech signal in the compressed high frequency band when the speech signal has a lower signal power level in the compressed high frequency band after compression than before compression, and where the gain controller attenuates a portion of the speech signal in the compressed high frequency band when the speech signal has a higher signal power level in the compressed high frequency band after compression than before compression; where the gain controller selects a level for the gain based on a slope of a noise floor present in the compressed high frequency band of the speech signal and a slope of a noise floor present in an uncompressed frequency band of the speech signal. - View Dependent Claims (18, 19, 20, 21)
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22. A speech system that improves the intelligibility of a processed speech, comprising:
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a frequency transformer device that converts a speech signal from time domain into frequency domain in real time; a spectral compressor device coupled to the frequency transformer that compresses a pre-selected high frequency band of the speech signal and maps the compressed high frequency band to a lower frequency band within a telephone pass band; a noise detector device that detects and measures a background noise level in the speech signal; and a gain controller device that applies a variable gain to the compressed high frequency band in relation to the level of the background noise in the speech signal, where the gain controller selects a level for the variable gain that substantially aligns a slope of a noise floor present in the compressed high frequency band with a slope of a noise floor present in an uncompressed frequency portion of the speech signal. - View Dependent Claims (23, 24, 25, 26)
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27. A speech system that improves the intelligibility and quality of a processed speech, comprising:
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a frequency transformer device that converts a speech signal into a spectrum of frequencies; a spectral compressor device electrically coupled to the frequency transformer that compresses a pre-selected high frequency band of the speech signal and maps the compressed high frequency band to a lower band limited frequency range; and a gain controller device that applies a variable gain to the compressed high frequency band, where the gain controller selects a level for the variable gain that counteracts an increase or decrease in noise floor in the compressed high frequency band due to the compression of the pre-selected high frequency band into the compressed high frequency band, and substantially aligns a slope of the noise floor in the compressed high frequency band with a slope of a noise floor present in an uncompressed frequency portion of the speech signal.
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Specification