Electrical Nerve Stimulation Based on Channel Specific Sequences

• US 20070156202A1
• Filed: 03/14/2007
• Published: 07/05/2007
• Est. Priority Date: 08/26/1999
• Status: Active Grant

• Current Assignee: Med El Elektromedizinische Geraete GmbH
• Original Assignee: Med El Elektromedizinische Geraete GmbH
• Inventors: Zierhofer, Clemens
• Granted Patent: US 7,937,157 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 2225/67 Implantable hearing aids or parts thereof not covered by H04R25/606

Abstract

A method of activating at least two electrodes in a multichannel electrode array using channel specific sampling sequences is presented. A channel specific sampling sequence is defined for each electrode, the sequence having a particular duration, pulse amplitude distribution, and number of pulses. A weighting factor is applied to the channel specific sampling sequence. Each electrode in the multichannel electrode array is then simultaneously activated using sign-correlated pulses, the sign-correlated pulses based on parameters of spatial channel interaction reflecting geometric overlapping of electrical fields from each electrode, non-linear compression, and each electrode'"'"'s weighted channel specific sampling sequence.

Claims

1. A method of activating electrodes in a multichannel electrode array using channel specific sampling sequences, the method comprising:

applying an acoustic representative electrical signal to a bank of filters, each filter in the bank of filters associated with a channel having an electrode;

deriving a weighting factor for each channel from the output of each channel filter;

applying the weighting factor to a channel specific sampling sequence having a selected duration, amplitude distribution, and number of pulses, creating a weighted channel specific sampling sequence; and

simultaneously activating each channel'"'"'s electrode using sign-correlated pulses, calculating amplitudes of the sign-correlated pulses based, at least in part, on;

parameters of spatial channel interaction reflecting geometric overlapping of electrical fields from each electrode; and

each electrode'"'"'s weighted channel specific sampling sequence.

2. A method according to claim 1, wherein the electrodes stimulate the acoustic nerve.

3. A method according to claim 1, wherein deriving the weighting factor comprises:

rectifying the output of each filter, creating a half-wave rectified signal; and

determining a maximum amplitude of each half-wave in the half-wave rectified signal.

4. A method according to claim 1, wherein the multichannel electrode array uses a monopolar electrode configuration having a remote ground.

5. A method according to claim 1, further comprising deriving pulse amplitudes of the channel specific sampling sequence by sampling a signal waveform.

6. A method according to claim 1, wherein each filter is a bandpass filter.

7. A method according to claim 1, wherein the multichannel electrode array is in a cochlear implant, and the weighting factor is transmitted to the cochlear implant.

8. A method of simultaneously activating at least two electrodes in a multichannel electrode array, the method comprising:

using sign-correlated pulses; and

calculating amplitudes of the sign-correlated pulses by taking into account parameters of spatial channel interaction reflecting geometric overlapping of electrical fields from each electrode.

9. An implant system comprising:

a multi-channel electrode array,

a memory device for storing for each electrode in the electrode array a channel specific sampling sequence having a predefined duration, amplitude, and number of pulses; and

a stimulator for applying a weighting factor to each channel specific sampling sequence so as to create a weighted channel specific sampling sequence for each electrode in the electrode array, and for simultaneously activating two or more electrodes in the electrode array using sign-correlated pulses, the sign-correlated pulses calculated based, at least in part, on;

parameters of spatial channel interaction reflecting geometric overlapping of electric fields from each electrode; and

each electrode'"'"'s weighted channel specific sampling.

10. The implant system according to claim 9, wherein the implant system includes a cochlear implant capable of stimulating the acoustic nerve.

11. The implant system according to claim 9, wherein the electrode array is arranged in a monopolar electrode configuration having a remote ground.

12. The implant system according to claim 9, wherein the channel specific sampling sequence pulse amplitudes are derived by sampling a signal waveform.

13. The implant system according to claim 12, wherein the signal waveform is a half period of a sinusoid between 0 and π

.

14. The implant system according to claim 12, wherein the signal waveform is a quarter period of a sinusoid between 0 and π

/2 so that pulse amplitude distribution monotonically increases.

15. The implant system according to claim 9, wherein the parameters of spatial channel interaction are based on a single electrode model having exponential decays of the potentials at both sides of the electrode.

16. The implant system according to claim 15, wherein the stimulator uses properties of a tri-diagonal matrix to determine amplitudes of the sign-correlated pulses.

17. The implant system according to claim 9, wherein the speech processor includes a filter bank for receiving an acoustic representative electrical signal, each filter in the bank of filters associated with one of the electrodes in the multi-channel electrode array, and wherein the speech processor derives a weighting factor for each electrode in the multi-channel electrode array from an associated channel filter.

18. The implant system according to claim 17, wherein each filter is a bandpass filter.

19. The implant system according to claim 18, wherein the duration and number of pulses in the channel specific sampling sequence is derived from the center frequency of the channel'"'"'s bandpass filter.

20. The implant system according to claim 15, wherein the duration and number of pulses in the channel specific sampling sequence is derived from the center frequency of the channel'"'"'s bandpass filter.