SIGNAL PROCESSOR

• US 20170323656A1
• Filed: 04/26/2017
• Published: 11/09/2017
• Est. Priority Date: 05/06/2016
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Elshamy, Samy, Fingscheidt, Tim, Madhu, Nilesh, Tirry, Wouter Joos
• Granted Patent: US 10,297,272 B2
• Time in Patent Office: Days
• CPC Class Codes: G10L 21/0208 Noise filtering
• CPC Class Codes: G10L 21/0364 for improving intelligibility
• CPC Class Codes: G10L 25/24 the extracted parameters being the cepstrum
• CPC Class Codes: G10L 25/90 Pitch determination of speech signals

Abstract

A signal processor comprising:

• • a signal-manipulation-block configured to:
    • receive a cepstrum-input-signal, wherein the cepstrum-input-signal is in the cepstrum domain and comprises a plurality of bins;
    • receive a pitch-bin-identifier that is indicative of a pitch-bin in the cepstrum-input-signal; and
    • generate a cepstrum-output-signal based on the cepstrum-input-signal by:
      • scaling the pitch-bin relative to one or more of the other bins of the cepstrum-input-signal; or
      • determining an output-pitch-bin-value based on the pitch-bin, and setting one or more of the other bins of the cepstrum-input-signal to a predefined value; or
      • determining an output-other-bin-value based on one or more of the other bins of the cepstrum-input-signal, and setting the pitch-bin to a predefined value.

Claims

1. A signal processor comprising:

a signal-manipulation-block configured to;

receive a cepstrum-input-signal, wherein the cepstrum-input-signal is in the cepstrum domain and comprises a plurality of bins;

receive a pitch-bin-identifier that is indicative of a pitch-bin in the cepstrum-input-signal; and

generate a cepstrum-output-signal based on the cepstrum-input-signal by;

scaling the pitch-bin relative to one or more of the other bins of the cepstrum-input-signal;

or

determining an output-pitch-bin-value based on the pitch-bin, and setting one or more of the other bins of the cepstrum-input-signal to a predefined value;

or

determining an output-other-bin-value based on one or more of the other bins of the cepstrum-input-signal, and setting the pitch-bin to a predefined value.

2. The signal processor of claim 1, wherein the signal-manipulation-block is configured to generate the cepstrum-output-signal by determining an output-zeroth-bin-value based on a zeroth-bin of the cepstrum-input-signal.

3. The signal processor of claim 1, wherein the signal-manipulation-block is configured to scale the pitch-bin relative to one or more of the other bins of the cepstrum-input-signal by:

applying a pitch-bin-scaling-factor to the pitch-bin of the cepstrum-input-signal; and

applying an other-bin-scaling-factor to one or more of the other bins of the cepstrum-input-signal;

wherein the other-bin-scaling-factor is different to the pitch-bin-scaling-factor.

4. The signal processor of claim 1, wherein the signal-manipulation-block is configured to scale the pitch-bin relative to one or more of the other bins of the cepstrum-input-signal by:

applying a pitch-bin-scaling-offset to the pitch-bin of the cepstrum-input-signal; and

applying an other-bin-scaling-offset to one or more of the other bins of the cepstrum-input-signal;

wherein the other-bin-scaling-offset is different to the pitch-bin-scaling-offset.

5. The signal processor of claim 1, wherein the pitch-bin-identifier is indicative of a plurality of pitch-bins that are representative of a fundamental frequency.

6. The signal processor of claim 1, wherein the cepstrum-input-signal is representative of a speech signal or a noise signal.

7. The signal processor of claim 1, wherein the signal-manipulation-block is configured to generate the cepstrum-output-signal by setting the amplitude of one or more of the other bins of the cepstrum-input-signal to zero.

8. The signal processor of claim 1, further comprising a memory configured to store an association between a plurality of pitch-bin-identifiers and a plurality of candidate-cepstral-vectors, wherein each of the candidate-cepstral-vectors defines a manipulation vector for the cepstrum-input-signal;

wherein the signal-manipulation-block is configured to;

determine a selected-cepstral-vector as the candidate-cepstral-vector that is stored in the memory associated with the received pitch-bin-identifier; and

generate the cepstrum-output-signal by applying the selected-cepstral-vector to the cepstrum-input-signal.

9. The signal processor of claim 8, wherein the candidate-cepstral-vectors define a manipulation vector that includes predefined other-bin-values for one or more bins of the cepstrum-input-signal that are not the pitch-bin, and optionally not the zeroth bin.

10. The signal processor of claim 8, wherein the plurality of candidate-cepstral-vectors are associated with speech components from a specific user.

11. The signal processor of claim 1, further comprising:

a pitch-estimation-block configured to;

receive the cepstrum-input-signal;

determine an amplitude of a plurality of the bins in the cepstrum-input-signal; and

determine the bin that has the highest amplitude as the pitch-bin.

12. The signal processor of claim 11, wherein the pitch-estimation-block is configured to determine an amplitude of a plurality of the bins in the cepstrum-input-signal that have a bin-index that is between an upper-cepstral-bin-index and a lower-cepstral-bin-index.

13. The signal processor of claim 1, further comprising:

a frequency-to-cepstrum-block configured to;

receive a frequency-input-signal; and

perform a DCTII or DFT on the frequency-input-signal in order to determine the cepstrum-input-signal based on the frequency-input-signal; and

a cepstrum-to-frequency-block configured to;

receive the cepstrum-output-signal; and

perform an inverse DCTII or an inverse DFT on the cepstrum-output-signal in order to determine a frequency-output-signal based on the cepstrum-output-signal.

14. The signal processor of claim 13, further comprising a sub-harmonic-attenuation-block, configured to attenuate one or more frequency bins in the frequency-output-signal that have a frequency-bin-index that is less than a frequency-domain equivalent of the pitch-bin-identifier in order to generate a sub-harmonic-attenuated-output-signal.

15. A speech processing system comprising the signal processor claim 1.