N band FM demodulation to aid cochlear hearing impaired persons

• US 8,670,582 B2
• Filed: 11/10/2009
• Issued: 03/11/2014
• Est. Priority Date: 11/10/2008
• Status: Active Grant

• Current Assignee: Oticon A/S (William Demant Fonden)
• Original Assignee: Oticon A/S (William Demant Fonden)
• Inventors: Lunner, Thomas, Pontoppidan, Niels Henrik
• Primary Examiner(s): NGUYEN, DUC MINH
• Assistant Examiner(s): Masson, Anita
• Application Number:
  US12/599,654
• Publication Number:
  US 20110249835A1
• Time in Patent Office: 1,582 Days
• Field of Search: 381/23.1, 381312-331, 381/72
• US Class Current: 381/312
• CPC Class Codes: A61N 1/36038 Cochlear stimulation
• CPC Class Codes: H04R 2225/43 Signal processing in hearing aids to enhance the speech intelligibility
• CPC Class Codes: H04R 2430/03 Synergistic effects of band splitting and sub-band processing
• CPC Class Codes: H04R 25/505 using digital signal processing

Abstract

A signal processing device comprising a signal processing unit for processing an electrical SPU-input signal comprising frequencies in the audible frequency range between a minimum frequency and a maximum frequency, and providing a processed SPU output signal. An FM to AM transformation unit transforms an FM2AM input signal originating from the SPU-input signal and comprising at least a part of the frequency range of the SPU-input signal from a frequency modulated signal to an amplitude modulated signal to provide an FM2AM output signal, which is used in the generation of the processed SPU output signal.

Claims

1. A signal processing device, comprising:

a signal processing unit configured to process an electrical SPU-input signal including frequencies in an audible frequency range between a minimum frequency and a maximum frequency, and configured to provide a processed SPU output signal, the signal processing unit including

an FM to AM transformation unit configured to transform an FM2AM input signal originating from the SPU-input signal and including at least a part of the frequency range of the SPU-input signal from a frequency modulated signal to an amplitude modulated signal, and configured to provide an FM2AM output signal, which is used in the generation of the processed SPU output signal, the FM to AM transformation unit including

a frequency demodulation unit configured to extract a frequency modulation function of the FM2AM input signal and configured to provide an FM2AM transformed signal, and

an AM modulator configured to perform amplitude modulation of the FM2AM input signal originating from the SPU-input signal with the FM2AM transformed signal to provide the FM2AM output signal.

2. A signal processing device according to claim 1 further comprising a time to time-frequency transformation unit providing a time varying representation of the SPU-input signal in a number of frequency ranges.

3. A signal processing device according to claim 1 comprising an AM-demodulation unit for extracting an amplitude modulation function am_n(t) of the at least one signal originating from the SPU-input signal, n being a frequency range index.

4. A signal processing device according to claim 1 comprising a frequency demodulation unit for extracting a frequency modulation function fm_n(t) of the at least one signal originating from the SPU-input signal, n being a frequency range index.

5. A signal processing device according to claim 4, wherein the FM to AM transformation of a signal originating from the SPU-input signal and comprising a frequency range p is based on the frequency modulation function fm_n(t) extracted from a signal comprising a frequency range n, where p can be equal to n or different from n.

6. A signal processing device according to claim 4 comprising a carrier unit for providing a sinusoidal with a carrier frequency equivalent to the middle of a frequency range n and amplitude and an AM modulator for modulating the sinusoidal with the demodulated FM signal fm_n(t) thereby providing the FM to AM transformation and the FM2AM output signal in frequency range n.

7. A signal processing device according to claim 4 comprising an AM modulator for modulating the SPU-input signal of the frequency range or channel n with the demodulated FM signal fm_n(t), thereby providing the FM to AM transformation and the FM2AM output signal in frequency range n.

8. A signal processing device according to claim 4 comprising a combiner unit for combining the at least one signal originating from the SPU-input signal, the amplitude modulation function, the frequency modulation function and/or the FM2AM transformed signal with weights and providing a weighted amplitude modulation function.

9. A signal processing device according to claim 3 comprising a combiner unit for combining the extracted amplitude modulation function am_n(t) and the FM2AM transformed signal of the corresponding frequency range with weights and providing a weighted amplitude modulation function.

10. A signal processing device according to claim 1 comprising a combiner unit for combining the at least one signal originating from the SPU-input signal and the FM2AM transformed signal with weights and providing a weighted amplitude modulation function.

11. A signal processing device according to claim 8, wherein

the combiner unit is configured to control the weights in dependence of the signal to noise ratio (SNR) of the SPU-input signal.

12. A signal processing device according to claim 8 comprising a carrier unit for providing a sinusoidal with a carrier frequency in, such as equivalent to the middle of, a frequency range n, and an AM modulator for amplitude modulating the sinusoidal with the weighted amplitude modulation function creating an amplitude modulated weighted output signal in that frequency range.

13. A signal processing device according to claim 8 comprising an AM modulator for amplitude modulating the SPU-input signal in a frequency range n with the weighted amplitude modulation function creating an amplitude modulated weighted output signal in that frequency range.

14. A signal processing device according to claim 1 comprising a FT-unit for providing a time-frequency to time transformation of a signal originating from the FM2AM signal(s) and/or from the weighted amplitude modulation functions and/or from the amplitude modulated weighted output signals to generate an SPU-output signal in the time domain.

15. A signal processing device according to claim 1, wherein

information contained in the frequency modulation of the electrical SPU-input signal is applied to the processed SPU output signal as amplitude modulation.

16. Use of a signal processing device according to claim 1 in a listening device, such as a hearing aid, e.g. a hearing instrument, or a head set, or a headphone or an active ear protection device.

17. A method of operating an audio processing device, the method comprising:

processing an SPU-input signal according to a user'"'"'s needs, the SPU-input signal including frequencies in an audible frequency range between a minimum frequency and a maximum frequency; and

providing a processed SPU output signal, wherein

the processing the SPU-input signal according to a user'"'"'s needs includes

providing an FM to AM transformation of an FM2AM input signal originating from the SPU-input signal and including at least a part of the frequency range of the SPU-input signal, and

providing an FM2AM output signal,

the providing the FM to AM transformation includes

extracting a frequency modulation function of the FM2AM input signal,

providing an FM2AM transformed signal based on said frequency modulation function, and

performing amplitude modulation of the FM2AM input signal originating from the SPU-input signal with the FM2AM transformed signal to provide said FM2AM output signal.

18. A method according to claim 17 wherein the processing of an SPU-input signal according to a user'"'"'s needs comprises that the FM2AM signal is used to amplitude modulate a constant envelope input signal to provide a resulting amplitude modulated signal, which is used as a basis for the processed SPU output signal.

19. A data processing system comprising a processor and program code means for causing the processor to perform the steps of the method according to claim 17.

20. A non-transitory computer readable medium encoded with instructions, wherein the instructions, when executed on a processor, cause the processor to perform a method comprising:

processing an SPU-input signal according to a user'"'"'s needs, the SPU-input signal including frequencies in an audible frequency range between a minimum frequency and a maximum frequency; and

providing a processed SPU output signal, wherein

the processing the SPU-input signal according to a user'"'"'s needs includes

providing an FM to AM transformation of an FM2AM input signal originating from the SPU-input signal and including at least a part of the frequency range of the SPU-input signal, and

providing an FM2AM output signal,

the providing the FM to AM transformation includes

extracting a frequency modulation function of the FM2AM input signal,

providing an FM2AM transformed signal based on said frequency modulation function, and

performing amplitude modulation of the FM2AM input signal originating from the SPU-input signal with the FM2AM transformed signal to provide said FM2AM output signal.