System for suppressing rain noise

• US 7,949,522 B2
• Filed: 12/08/2004
• Issued: 05/24/2011
• Est. Priority Date: 02/21/2003
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: QNX Software Systems Company (Blackberry Limited)
• Inventors: Groves, Adrian R., Hetherington, Phillip A.
• Primary Examiner(s): Opsasnick; Michael N
• Application Number:
  US11/006,935
• Publication Number:
  US 20050114128A1
• Time in Patent Office: 2,358 Days
• Field of Search: 704/226, 704/233
• US Class Current: 704/226
• CPC Class Codes: G10L 21/0208 Noise filtering
• CPC Class Codes: G10L 21/0232 Processing in the frequency domain

Abstract

A voice enhancement logic improves the perceptual quality of a processed signal. The voice enhancement system includes a noise detector and a noise attenuator. The noise detector detects and models the noise associated with rain. The noise attenuator dampens or reduces the rain noise from a signal to improve the intelligibility of an unvoiced, a fully voiced, or a mixed voice segment.

Claims

1. A system for suppressing rain noise from a voiced or unvoiced signal, comprising:

a noise detector configured to fit a line to an input signal and identify whether a noise from the input signal is associated with rain based on a correlation between the line and the input signal, where the noise detector comprises a non-transitory medium or circuit; and

a noise attenuator electrically connected to the noise detector to substantially remove noise associated with rain from the input signal.

2. The system for suppressing rain noise of claim 1 where the noise detector is configured to model a portion of the input signal.

3. The system of claim 1 where the noise detector is configured to model a rain event by calculating a correlation factor.

4. The system of claim 1 where the noise detector is configured to prevent one or more attributes of a modeled rain noise from exceeding a predefined value.

5. The system of claim 1 where the noise detector is configured to limit a rain noise correction when a vowel or a harmonic like structure is detected.

6. The system of claim 1 where the noise detector is configured to derive an average rain noise model and the average rain noise model is not updated when a voiced or a mixed voice signal is detected.

7. The system of claim 1 where the noise detector is configured to derive an average rain noise model that is derived by a weighted average of other modeled signals analyzed earlier in time.

8. The system of claim 1 where the noise attenuator is configured to substantially remove the noise associated with rain and a continuous noise from the input signal.

9. The system of claim 1 further comprising a residual attenuator coupled to the noise detector and the noise attenuator to dampen signal power in a frequency range when a large increase in a signal power is detected in the frequency range.

10. The system of claim 1 further including an input device coupled to the noise detector, the input device configured to convert sound waves into analog signals.

11. The system of claim 1 further including a pre-processing system coupled to the noise detector, the pre-processing system configured to pre-condition the input signal before the rain noise detector processes it.

12. The system of claim 11 where the pre-processing system comprises first and second microphones spaced apart and configured to exploit a lag time of a signal that may arrive at the different microphones.

13. The system of claim 12 further comprising control logic that automatically selects a microphone and a channel that senses the least amount of noise in the input signal.

14. The system of claim 12 where the noise detector comprises a first noise detector, the system further comprising a second noise detector coupled to the first noise detector and the first microphone.

34. The system of claim 1 where the noise detector is configured to identify that the input signal comprises a rain event when a high correlation exists between the line and the portion of the input signal.

39. The system of claim 1 further comprising a background noise estimator coupled to the noise detector, the background noise estimator configured to measure a continuous noise that occurs near a receiver.

15. A system for detecting rain noise from a voiced and unvoiced signal, comprising:

a time frequency transform logic that converts a time varying input signal into the frequency domain;

a background noise estimator coupled to the time frequency transform logic, the background noise estimator configured to measure the continuous noise that occurs near a receiver; and

a rain noise detector coupled to the background noise estimator, the rain noise detector configured to derive a correlation between a line and a portion of the input signal to determine, based on the correlation, whether the portion of the input signal contains noise associated with rain.

16. The system of claim 15 further comprising a transient detector configured to disable the background noise estimator when a non-periodic transient signal is detected.

17. The system of claim 15 further comprising a signal discriminator coupled to the rain noise detector, the signal discriminator configured to identify voice and noise segments of the input signal.

18. The system of claim 15 further comprising a rain noise attenuator coupled to the rain noise detector, the rain noise attenuator configured to reduce the noise associated with the rain that is sensed by the receiver.

19. The system of claim 18 where the noise attenuator is configured to substantially remove the noise associated with the rain from the input signal.

20. The system of claim 15 further comprising a residual attenuator coupled to the background noise estimator operable to dampen signal power in a frequency range when a large increase in signal power is detected in the frequency range.

21. A system for suppressing rain noise from a voiced or unvoiced signal, comprising:

a time frequency transform logic that converts a time varying input signal into the frequency domain;

a background noise estimator coupled to the time frequency transform logic, the background noise estimator configured to measure the continuous noise that occurs near a receiver;

a rain noise detector means coupled to the background noise estimator, the rain noise detector configured to fit a line to a portion of an input signal to identify whether the portion of the input signal contains a rain event; and

a rain noise attenuator coupled to the rain noise detector means, the rain noise attenuator being configured to remove a noise associated with rain that is sensed by the receiver.

22. A method of dampening a noise associated with rain from an input signal comprising:

converting a time varying signal to a complex spectrum;

estimating a background noise;

fitting a line to a portion of the input signal;

identifying, by a noise detector that comprises a circuit, that a noise is associated with rain when a high correlation exists between the line and the portion of the input signal; and

passing the input signal through a noise attenuator to dampen the noise associated with rain from the input signal to obtain a noise-reduced signal.

23. The method of claim 22 where the act of estimating the background noise comprises estimating the background noise when a non-periodic transient is not detected.

24. The method of claim 22 where the act of passing the input signal through the noise attenuator comprises substantially removing a rain noise from the input signal.

35. The method of claim 22 where the act of fitting the line comprises fitting the line to the portion of the input signal to identify whether the portion of the input signal contains a rain event.

25. A method of removing rain noise from an input signal comprising:

converting a time varying signal to a complex spectrum;

estimating a background noise;

fitting a line to a portion of the input signal;

identifying that a noise is associated with rain, by a noise detector that comprises a computer processor that executes instructions stored on a non-transitory computer-readable medium to identify whether the noise is associated with rain, when a high correlation exists between the line and the portion of the input signal; and

passing the input signal through a noise attenuator to remove the noise associated with rain from the input signal to obtain a noise-reduced signal.

36. The method of claim 25 where the act of fitting the line comprises fitting the line to the portion of the input signal to identify whether the portion of the input signal contains a rain event.

26. A computer-readable storage medium having software embodied therein that controls a detection of a noise associated with water falling through the air, the software comprising:

a detector that converts sound waves into electrical signals;

a spectral conversion logic that converts the electrical signals from a first domain to a second domain; and

a signal analysis logic that fits a line to a portion of the sound waves in the second domain, and where the signal analysis logic identifies whether the portion of the sound waves contains a rain event based on a correlation between the line and the portion of the sound waves in the second domain.

27. The medium of claim 26 further comprising logic that derives a portion of a voiced signal masked by noise.

28. The medium of claim 26 further comprising logic that attenuates a portion of the sound waves.

29. The medium of claim 26 further comprising attenuator logic operable to limit a power in a selected frequency range.

30. The medium of claim 26 further comprising noise estimation logic that measures a continuous or ambient noise sensed by the detector.

31. The medium of claim 30 further comprising a transient logic that disables the estimation logic when an increase in power is detected.

32. The medium of claim 26 where the signal analysis logic is coupled to an audio system of a vehicle.

33. The medium of claim 26 where the signal analysis logic models only the sound waves that are associated with rain.

37. A system for suppressing rain noise, comprising:

a rain noise detector that analyzes a detected sound to determine whether the detected sound contains a noise associated with rain, where the rain noise detector identifies multiple high-energy frequency bands in the detected sound that have higher energies than their adjacent frequency bands, where the rain noise detector compares the high-energy frequency bands to a model that corresponds to rain noise, where the rain noise detector identifies whether the high-energy frequency bands are associated with rain based on a fit between the model and the energy levels of the high-energy frequency bands, and where the rain noise detector comprises a non-transitory medium or circuit; and

a rain noise attenuator coupled with the rain noise detector to dampen one or more portions of the detected sound that are identified by the rain noise detector as being associated with rain.

38. The system of claim 37 further comprising a background noise estimator coupled to the rain noise detector, the background noise estimator configured to measure a continuous noise that occurs near a receiver.