System for detecting speech with background voice estimates and noise estimates

1. A process that improves speech detection by processing a limited frequency band comprising:

encoding a limited frequency band of an input into a signal by varying an amplitude of a pulse width modulated signal that is limited to a plurality of predefined values;

separating the signal into frequency bins in which each frequency bin identifies an amplitude and a phase;

estimating a signal strength of a background voice segment in time;

estimating a distribution of noise to an average acoustic power of one or a plurality of frequency bins;

comparing a signal-to-noise ratio of each frequency bin to a maximum of the estimated signal strength of the background voice segment and the estimated distribution of noise to the average acoustic power; and

identifying a speech segment from noise that surrounds the speech segment based on the comparison.

2. The process that improves speech detection of claim 1 , where a Fast Fourier transform separates the signal into frequency bins.

3. The process that improves speech detection of claim 1 , where the act of estimating of the signal strength of the background voice segment comprises an estimate of a time smoothed signal.

4. The process that improves speech detection of claim 3 , where the act of estimating of the signal strength of the background voice segment comprises measuring a signal-to-noise ratio of the time smoothed signal.

5. The process that improves speech detection of claim 4 , further comprising modifying the estimation of the signal strength of the background voice segment through a multiplication with a scalar quantity.

6. The process that improves speech detection of claim 4 , further comprising modifying the estimation of the signal strength of the background voice segment through a subtraction of an offset.

7. The process that improves speech detection of claim 1 , further comprising modifying the estimation of the distribution of noise the average acoustic power through a multiplication with a scalar quantity.

8. The process that improves speech detection of claim 1 , further comprising modifying the estimation of the distribution of noise to the average acoustic power through an addition of an offset.

9. A process that improves speech processing by processing a limited frequency band comprising:

converting a limited frequency band of a continuously varying input into a digital-domain signal;

converting the digital-domain signal into a frequency-domain signal;

estimating a signal strength of a smoothed background voice segment in time of the digital-domain signal relative to noise;

estimating a noise-variance of a segment of the digital-domain signal;

comparing an instant signal-to-noise ratio of the digital-domain signal to the estimated signal strength of the smoothed background voice segment in time of the digital domain signal relative to noise and the estimated noise-variance; and

identifying a speech segment when the instant signal-to-noise ratio of the digital-domain signal exceeds a maximum of the estimated signal strength of the smoothed background voice segment relative to noise and the estimated noise variance.

10. The process that improves speech processing of claim 9 , further comprising modifying the estimation of the signal strength of the smooth background voice segment through a multiplication with a scalar quantity.

11. The process that improves speech processing of claim 10 , where the scalar quantity is less than one.

12. The process that improves speech processing of claim 9 , further comprising modifying the estimation of the signal strength of the smoothed background voice segment through a subtraction of an offset.

13. The process that improves speech processing of claim 9 , further comprising modifying the estimation of the noise-variance through a multiplication with a scalar quantity.

14. The process that improves speech processing of claim 13 , where the scalar quantity is greater than about one.

15. The process that improves speech processing of claim 9 , further comprising modifying the estimation of the noise-variance through an addition of an offset.

16. A system that detects a speech segment that includes an unvoiced, a fully voiced, or a mixed voice content comprising:

a digital converter that converts a time-varying input signal into a digital-domain signal;

a window function configured to pass signals within a programmed aural frequency range while substantially blocking signals above and below the programmed aural frequency range when multiplied by an output of the digital converter;

a frequency converter that converts the signals passing within the programmed aural frequency range into a plurality of frequency bins;

a background voice detector configured to estimate a strength of a background speech segment relative to noise of selected portions of an aural spectrum;

a noise estimator configured to estimate a maximum distribution of noise to an average of an acoustic noise power of some of the plurality of frequency bins; and

a voice detector configured to compare an instant signal-to-noise ratio of a desired speech segment to a maximum of an output of the background voice detector and an output of the noise estimator.

17. The system of claim 16 further comprising an end-pointer that applies one or more static or dynamic rules to determine a beginning or an end of the desired speech segment processed by the voice detector.