N BAND FM DEMODULATION TO AID COCHLEAR HEARING IMPAIRED PERSONS

• US 20110249835A1
• Filed: 11/10/2008
• Published: 10/13/2011
• 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
• Granted Patent: US 8,670,582 B2
• Time in Patent Office: Days
• 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

The invention relates to: 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. The invention further relates to its use and to a method of operating an audio processing device. The object of the present invention is to provide a scheme for improving a user'"'"'s perception of an acoustic signal. The problem is solved in that an FM to AM transformation unit for transforming 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. This has the advantage of providing an improved perception by a hearing impaired user of an input sound.

Claims

1. 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, comprising an FM to AM transformation unit for transforming 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.

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 adapted to provide that 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 adapted 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 adapted to provide that 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 comprising processing an SPU-input signal according to a user'"'"'s needs, the SPU-input signal comprising frequencies in a range between a minimum frequency and a maximum frequency, and providing a processed SPU output signal, wherein the processing of an SPU-input signal according to a user'"'"'s needs comprises providing an FM to AM transformation of at least one signal originating from the SPU-input signal and comprising at least a part of the frequency range of the SPU-input signal, and providing an FM2AM 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 computer readable medium for storing a computer program comprising program code means for causing a data processing system to perform the steps of the method according to claims 17.