Signature noise removal

• US 20070078649A1
• Filed: 11/30/2006
• Published: 04/05/2007
• Est. Priority Date: 02/21/2003
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: QNX Software Systems Limited (Canada) (Blackberry Limited)
• Inventors: Paranjpe, Shreyas, Hetherington, Phillip
• Granted Patent: US 8,271,279 B2
• Time in Patent Office: Days
• US Class Current: 704/226
• CPC Class Codes: G10L 2021/02085 Periodic noise
• CPC Class Codes: G10L 21/0216 characterised by the method used for estimating noise
• CPC Class Codes: G10L 21/0232 Processing in the frequency domain
• CPC Class Codes: G10L 25/45 characterised by the type of analysis window

Abstract

A speech enhancement system improves the perceptual quality of a processed voice signal. The system improves the perceptual quality of a voice signal by removing unwanted noise components from a voice signal. The system removes undesirable signals that may result in the loss of information. The system receives and analyzes signals to determine whether an undesired random or persistent signal corresponds to one or more modeled noises. When one or more noise components are detected, the noise components are substantially removed or dampened from the signal to provide a less noisy voice signal.

Claims

1. A speech enhancement system operative to suppress noise from a received signal comprising:

a noise detector operative to store a model of a noise component within a memory and operative to detect the presence of a noise component in the received signal; and

a noise attenuator in communication with the noise detector and operative to substantially remove the noise component when an attribute of the received signal substantially matches an attribute of the stored model of the noise component.

2. The system of claim 1 where the noise detector is operative to compare the attribute of the received signal to the attribute of the stored model of the noise component.

3. The system of claim 2 where the model of the noise component comprises a spectral attribute of the noise component and a temporal attribute of the noise component.

4. The system of claim 3 where the temporal component comprises a first sound event and a substantially similar second sound event separated by a period of time.

5. The system of claim 3 where the spectral component comprises one or more attributes of a spectral shape of a sound event associated with a road noise.

6. The system of claim 3 where the noise detector and the noise attenuator are coupled to a vehicle.

7. A noise detector operative to detect a noise that may affect a signal comprising:

an analog to digital converter operative to convert a received signal into a digital signal;

a windowing function operative to separate the received signal into a plurality of signal analysis windows;

a transform logic operative to transform the plurality of signal analysis windows to the frequency domain; and

a modeling logic operative to store attributes of a noise, and compare the stored attributes to a transformed signal to identify a noise.

8. The noise detector of claim 7 where the analog to digital converter converts the received signal into a pulse code modulated signal.

9. The noise detector of claim 7 where the windowing function comprises a Hanning window function generator.

10. The noise detector of claim 7 where the transform module comprises a Fast Fourier Transform logic.

11. The noise detector of claim 10 where the attributes of the noise comprise a temporal characteristic substantially unique to an undesired signal.

12. The noise detector of claim 10 where the attributes of the noise comprise a spectral characteristic substantially unique to an undesired signal.

13. The noise detector of claim 10 where the attributes of the noise comprise temporal characteristics and spectral characteristics substantially unique to an undesired signal.

14. The noise detector of claim 13 where the attributes of the noise comprise spectral shape characteristics of two sound events.

15. The noise detector of claim 14 where the modeling logic is operative to fit a function to a selected portion of the signal in a time-frequency domain to evaluate the spectro-temporal shape characteristics of the two sound events.

16. The noise detector of claim 10 further comprising a residual attenuator operative to track the power spectrum of the received.

17. The noise detector of claim 16 where the residual attenuator is operative to limit the transmitted power in a low frequency range to a predetermined threshold when a large increase in signal power is detected.

18. The noise detector of claim 17 where the predetermined threshold is based on the average spectral power of the received signal in the low frequency range from an earlier period in time.

19. A method operative to substantially remove noises from a signal comprising:

modeling characteristics of a noise;

analyzing the signal to determine whether characteristics of the signal correspond to the modeled characteristics of the noises; and

substantially removing the characteristics of the noise from the received signal.

20. The method of claim 19 further comprising modeling a temporal separation between more than one sound events.

21. The method of claim 20 where the spectral shape attributes of the more than one sound event comprises a broadband event with peak energy levels occurring at relatively lower frequencies.