System for improving speech intelligibility through high frequency compression
First Claim
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1. A system, comprising:
- a computer processor;
a frequency transformer configured to convert a speech signal into a spectrum of frequencies; and
a spectral compressor regulated by the computer processor and coupled with the frequency transformer, where the spectral compressor is configured to define a lower cutoff frequency within a frequency passband having a passband upper frequency limit, where the spectral compressor is configured to compress a pre-selected high frequency band of the speech signal between the lower cutoff frequency and a frequency component above the passband upper frequency limit, and where the spectral compressor is configured to map the compressed high frequency band to a lower frequency range below the passband upper frequency limit in response to a determination that a signal-to-noise ratio of the speech signal in the lower frequency range before compression is less than a signal-to-noise ratio of the speech signal in the lower frequency range after compression.
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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.
93 Citations
21 Claims
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1. A system, comprising:
- a computer processor;
a frequency transformer configured to convert a speech signal into a spectrum of frequencies; and a spectral compressor regulated by the computer processor and coupled with the frequency transformer, where the spectral compressor is configured to define a lower cutoff frequency within a frequency passband having a passband upper frequency limit, where the spectral compressor is configured to compress a pre-selected high frequency band of the speech signal between the lower cutoff frequency and a frequency component above the passband upper frequency limit, and where the spectral compressor is configured to map the compressed high frequency band to a lower frequency range below the passband upper frequency limit in response to a determination that a signal-to-noise ratio of the speech signal in the lower frequency range before compression is less than a signal-to-noise ratio of the speech signal in the lower frequency range after compression. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
- a computer processor;
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11. A method, comprising:
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identifying a frequency passband having a passband upper frequency limit; defining a lower cutoff frequency within the frequency passband; receiving a speech signal having a frequency spectrum, a highest frequency component of which is greater than the passband upper frequency limit; calculating a signal-to-noise ratio of the speech signal in a first frequency range between the lower cutoff frequency and the passband upper frequency limit; and compressing a portion of the speech signal spectrum in a second frequency range between the lower cutoff frequency and the highest frequency component of the speech signal into the first frequency range between the lower cutoff frequency and the passband upper frequency limit in response to a determination that the signal-to-noise ratio of the speech signal in the first frequency range before compression is less than a signal-to-noise ratio of the speech signal in the first frequency range after compression. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A non-transitory computer-readable medium with instructions stored thereon, where the instructions are executable by a processor to cause the processor to perform the steps of:
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identifying a frequency passband having a passband upper frequency limit; defining a lower cutoff frequency within the frequency passband; receiving a speech signal having a frequency spectrum, a highest frequency component of which is greater than the passband upper frequency limit; calculating a signal-to-noise ratio of the speech signal in a first frequency range between the lower cutoff frequency and the passband upper frequency limit; and compressing a portion of the speech signal spectrum in a second frequency range between the lower cutoff frequency and the highest frequency component of the speech signal into the first frequency range between the lower cutoff frequency and the passband upper frequency limit in response to a determination that the signal-to-noise ratio of the speech signal in the first frequency range before compression is less than a signal-to-noise ratio of the speech signal in the first frequency range after compression. - View Dependent Claims (18, 19, 20, 21)
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Specification