Compressed neural coding

• US 20050192648A1
• Filed: 03/31/2005
• Published: 09/01/2005
• Est. Priority Date: 08/21/2000
• Status: Active Grant

• Current Assignee: Cochlear Limited
• Original Assignee: Cochlear Limited
• Inventors: Buechner, Andreas, Pesch, Joerg, Parker, John, Patrick, James F., Von Wallenberg, Ernst, Majoral, Marc, Killian, Matthijs, van Dijk, Bas
• Granted Patent: US 7,822,478 B2
• Time in Patent Office: Days
• US Class Current: 607/57
• CPC Class Codes: A61N 1/0541 Cochlear electrodes
• CPC Class Codes: A61N 1/36038 Cochlear stimulation
• CPC Class Codes: H04R 2225/43 Signal processing in hearing aids to enhance the speech intelligibility

Abstract

An embodiment of the present invention takes masking effects into consideration when determining stimulations signals for neural stimulation. These masking effects may be modeled using user-specific models determined by taking measurements for an implant system of an implant recipient. Or, the model may correspond to a group of individuals sharing a common characteristic or the population as a whole. These models may be, for example, psycho-physical or electrophysiological models.

Claims

1. A method of neural stimulation, comprising:

determining a plurality of stimulation signals based on a received acoustical signal;

selecting a subset of one or more of the plurality of stimulation signals based on information indicative of a masking effect of at least one of the plurality of stimulation signals; and

applying stimuli to a user using the selected subset of stimulation signals.

2. The method of claim 1, wherein the information indicative of the masking effect is derived from a model indicative of a masking effect for a population of people.

3. The method of claim 2, wherein the plurality of people is a subset of people sharing a common characteristic.

4. The method of claim 1, wherein the information indicative of the masking effect is derived from a user-specific model determined for the recipient.

5. The method of claim 1, wherein the information indicative of the masking effect is derived from psychophysical measurements.

6. The method of claim 5, wherein the psychophysical measurements are psychoacoustic measurements.

7. The method of claim 5, wherein the psychophysical measurements are psycho-electrical measurements.

8. The method of claim 5, wherein the information indicative of the masking effect is determined by applying a masker stimulus on a masker electrode of an electrode array implanted in the user and determining a threshold value for a probe stimulus on a probe electrode above which sound from the probe stimulus is audible to the user in the presence of the masker stimulus.

9. The method of claim 1, wherein the information indicative of a masking effect is derived from electrophysiological measurements.

10. The method of claim 9, wherein the electrophysiological measurements are determined by measuring Electrically Evoked Compound Action Potentials.

11. The method of claim 9, wherein the electrophysiological measurements are determined by measuring Electrically Evoked Auditory Brainstem Potentials.

12. The method of claim 9, wherein the electrophysiological measurements are determined by measuring Cortically Evoked potentials.

13. The method of claim 9 wherein the electrophysiological measurements are determined by a method comprising:

applying a masker signal on a first electrode of an electrode array implanted in the recipient;

applying a probe signal on a second electrode of the electrode array; and

measuring a threshold indicative of neural activity of the recipient due to the application of the masker and probe signals.

14. The method of claim 1, wherein selecting a subset of one or more of the stimulation signals, comprises:

selecting a subset of stimulation signals from the determined plurality of stimulation signals based on an amplitude for each of the plurality of stimulation signals;

determining whether one or more of the selected subset of stimulation signals is masked by other signals in the selected subset of stimulation signals based on information indicative of a masking effect of one or more of the other stimulation signals;

modifying the selected subset of stimulation signals based on the determination of whether one or more of the selected subset of stimulation signals is masked.

15. The method of claim 14, wherein modifying the selected plurality of stimulation signals comprises:

deleting stimulation signals from the subset that were determined to be masked.

16. The method of claim 1, wherein selecting a subset of one or more of the stimulation signals comprises:

selecting a first stimulation signal from the determined plurality of stimulation signals based on an amplitude of the first stimulation signal;

determining a masking effect of the selected stimulation signal; and

selecting a next stimulation signal from the determined plurality of stimulation signals based on an amplitude of the next stimulation signal and the determined masking effect.

17. The method of claim 16 further comprising:

iteratively performing the steps of determining a masking effect of the selected stimulation signals and selecting a next stimulation signal until a predetermined number of stimulation signals are selected.

18. The method of claim 1, wherein the applying of the stimuli includes electrical stimulation of the auditory system.

19. The method of claim 1, wherein the stimuli are applied using an electrode array comprising a plurality of electrodes.

20. The method of claim 1, wherein the user has a cochlear implant and wherein the stimuli are applied using the cochlear implant.

21. The method of claim 1, wherein the user has an auditory brainstem implant and wherein the stimuli are applied using the auditory brainstem implant.

22. The method of claim 1, wherein the user uses an electroacoustical device, and wherein the stimuli are applied using the electroacoustical device.

23. The method of claim 1, wherein the information indicative of a masking effect takes temporal masking effects into account.

24. A system for neural stimulation, comprising:

a microphone capable of receiving an acoustic signal;

a speech processing unit capable of determining a plurality of stimulation signals based on the received acoustical signal and selecting a subset of one or more of the plurality of stimulation signals based on information indicative of a masking effect of at least one of the plurality of stimulation signals; and

an implant capable of applying stimuli to a user using the selected subset of stimulation signals.

25. The system of claim 24, wherein the information indicative of the masking effect is derived from a model indicative of a masking effect for a population of people.

26. The system of claim 25, wherein the plurality of people is a subset of people sharing a common characteristic.

27. The system of claim 24, wherein the information indicative of the masking effect is derived from a user-specific model determined for the recipient.

28. The system of claim 24, wherein the information indicative of the masking effect is derived from psychophysical measurements.

29. The system of claim 28, wherein the psychophysical measurements are psychoacoustic measurements.

30. The system of claim 28, wherein the psychophysical measurements are psycho-electrical measurements.

31. The system of claim 28, wherein the information indicative of the masking effect is determined by applying a masker stimulus on a masker electrode of an electrode array implanted in the user and determining a threshold value for a probe stimulus on a probe electrode above which sound from the probe stimulus is audible to the user in the presence of the masker stimulus.

32. The system of claim 24, wherein the information indicative of a masking effect is derived from electrophysiological measurements.

33. The system of claim 32, wherein the electrophysiological measurements are determined by measuring Electrically Evoked Compound Action Potentials.

34. The system of claim 32, wherein the electrophysiological measurements are determined by measuring Electrically Evoked Auditory Brainstem Potentials.

35. The system of claim 32, wherein the electrophysiological measurements are determined by measuring Cortically Evoked potentials.

36. The system of claim 24, wherein the speech processing unit in selecting a subset of one or more of the stimulation signals, is further capable of selecting a subset of stimulation signals from the determined plurality of stimulation signals based on an amplitude for each of the plurality of stimulation signals;

determining whether one or more of the selected subset of stimulation signals is masked by other signals in the selected subset of stimulation signals based on information indicative of a masking effect of one or more of the other stimulation signals; and

modifying the selected subset of stimulation signals based on the determination of whether one or more of the selected subset of stimulation signals is masked.

37. The system of claim 36, wherein the speech processing unit in modifying the selected plurality of stimulation signals is capable of deleting stimulation signals from the subset that were determined to be masked.

38. The system of claim 24, wherein the speech processing unit in selecting a subset of one or more of the stimulation signals is further capable of selecting a first stimulation signal from the determined plurality of stimulation signals based on an amplitude of the first stimulation signal;

determining a masking effect of the selected stimulation signal; and

selecting a next stimulation signal from the determined plurality of stimulation signals based on an amplitude of the next stimulation signal and the determined masking effect.

39. The system of claim 38 wherein the speech processing unit is capable of iteratively performing the steps of determining a masking effect of the selected stimulation signals and selecting a next stimulation signal until a predetermined number of stimulation signals are selected.

40. The system of claim 24 wherein the implant is capable of electrical stimulation of the auditory system.

41. The system of claim 24, wherein the implant is an electrode array comprising a plurality of electrodes.

42. The system of claim 24, wherein the implant is a cochlear implant.

43. The system of claim 24, wherein the implant is an auditory brainstem implant.

44. The system of claim 24, wherein the implant is an electroacoustical device.

45. The system of claim 24, wherein the information indicative of a masking effect takes temporal masking effects into account.

46. A system for neural stimulation, comprising:

means for determining a plurality of stimulation signals based on a received acoustical signal;

means for selecting a subset of one or more of the plurality of stimulation signals based on information indicative of a masking effect of at least one of the plurality of stimulation signals; and

means for applying stimuli to a user using the selected subset of stimulation signals.