Multichannel cochlear implant system including wearable speech processor

• US 5,603,726 A
• Filed: 02/26/1993
• Issued: 02/18/1997
• Est. Priority Date: 09/22/1989
• Status: Expired due to Term

• Current Assignee: Alfred E. Mann Foundation For Scientific Research
• Original Assignee: Alfred E. Mann Foundation For Scientific Research
• Inventors: Schulman, Joseph H., Gord, John C., Strojnik, Primoz, Whitmoyer, David I.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US08/023,584
• Time in Patent Office: 1,453 Days
• Field of Search: 607/56, 607/57
• US Class Current: 607/57
• CPC Class Codes: A61N 1/36038 Cochlear stimulation
• CPC Class Codes: A61N 1/36185 Selection of the electrode configuration
• CPC Class Codes: A61N 1/37252 Details of algorithms or data aspects of communication system, e.g. handshaking, transmitting specific data or segmenting data
• CPC Class Codes: H04R 2225/67 Implantable hearing aids or parts thereof not covered by H04R25/606
• CPC Class Codes: H04R 2460/03 Aspects of the reduction of energy consumption in hearing devices
• CPC Class Codes: H04R 25/505 using digital signal processing

Abstract

A tissue stimulating system including an external transmitter for transmitting data to an implanted stimulator including a processor for generating stimulation signals for application to a plurality of tissue stimulating electrodes. The processor selectively monitors the electrodes and/or voltages generated in the stimulator and generates stimulator status indicating signals for transmission to the external transmitter. The external processor receives and processes such status indicating signals.

Claims

1. A system for electrically stimulating sensory nerves in the cochlea via electrically powered stimulating electrodes, said system including:

a wearable speech processor comprising;

means for generating a plurality of channels of electrical information in response to an external audio stimulus,

means for generating a power signal,

means for transmitting said plurality of channels of electrical information and said power signal across the skin of a patient to an implantable device, and power means for providing operating power to said wearable speech processor; and

an implantable cochlear stimulator (ICS), said ICS comprising;

power receiving means for receiving said power signal from said power signal generating means of said wearable speech processor,

feedback means for controlling the amount of power received by said ICS through said power signal,

a plurality of storage means for storing an electrical charge from power received through said power receiving means,

signal receiving means for receiving the plurality of channels of electrical information and converting the electrical information in each channel to a corresponding data signal, thereby providing a plurality of data channels, each containing data signals,

an intracochlear electrode array comprising a plurality of cochlea-stimulating electrodes, and

coupling means for selectively coupling each cochlea-stimulating electrode of said electrode array to a respective one of said plurality of storage means and for sourcing an amount of current therefrom that varies as a function of the data signals present within a corresponding one of the plurality of data channels.

2. The system for electrically stimulating sensory nerves in the cochlea as set forth in claim 1 wherein said ICS includes means for sensing at least one operating parameter associated with said ICS and transmitting means for transmitting said at least one operating parameter to said wearable speech processor;

and further wherein said wearable speech processor further includes receiving means for receiving the at least one operating parameter from said ICS and means for monitoring the operation of the ICS as manifest by said at least one operating parameter.

3. The system for electrically stimulating sensory nerves in the cochlea as set forth in claim 2 wherein said wearable speech processor includes a wearable processor, a connecting cable, and a headpiece, and wherein the wearable processor includes means for modulating the power signal with the plurality of channels of electrical information to produce a modulated power signal, and wherein the headpiece includes a transmitting coil and a receiving coil that are each electrically connected through the connecting cable with the wearable processor, and wherein the wearable processor includes means for applying the modulated power signal to the transmitting coil in order to produce electromagnetic energy that is transmitted to the power receiving means and the signal receiving means of the ICS, and wherein the receiving means of the wearable processor includes means for receiving the at least one operating parameter from the ICS through said receiving coil.

4. The system for electrically stimulating sensory nerves in the cochlea as set forth in claim 3 wherein said signal receiving means of said ICS includes an implantable receiving coil through which the electromagnetic energy produced by the transmitting coil of the headpiece of the wearable speech processor is received;

and further wherein the transmitting means of said ICS includes an implantable transmitting coil and means for generating a carrier signal modulated with the at least one operating parameter of said ICS to produce a modulated carrier signal, and means for applying the modulated carrier signal to the implantable transmitting coil for producing electromagnetic energy that is coupled to the receiving coil in the headpiece of the wearable speech processor.

5. The system for electrically stimulating sensory nerves in the cochlea as set forth in claim 4 wherein said headpiece further includes a microphone for sensing the external audio stimulus and generating an audio electrical signal in response thereto.

6. The system for electrically stimulating sensory nerves in the cochlea as set forth in claim 5 wherein said wearable processor includes:

audio front end circuitry means, including automatic gain control means, for receiving and amplifying said audio electrical signal generated by said microphone and generating an amplified audio electrical signal therefrom;

a multichannel filter bank that comprises a plurality of bandpass filters, each having a different passband, said amplified audio electrical signal being applied to each of said plurality of bandpass filters, an electrical analog signal appearing at an output of each of said plurality of bandpass filters as a function of the frequencies present in said amplified audio electrical signal;

conversion means for converting the electrical analog signal appearing at the output of each of said plurality of bandpass filters to a corresponding digital signal, whereby a digital signal is generated for each of a plurality of audio channels, where each audio channel corresponds to one of said plurality of bandpass filters;

processor means for processing said digital signals in each audio channel and generating said plurality of channels of electrical information as a function thereof.

7. The system for electrically stimulating sensory nerves in the cochlea as set forth in claim 6 wherein the power receiving means and the signal receiving means of said ICS comprise the implantable receiving coil and an implantable receiver circuit means coupled to the implantable receiving coil for:

(a) filtering out dc power from the modulated power signal, (b) demodulating the modulated power signal in order to recover the plurality of channels of electrical information therefrom, and (c) converting the electrical information in each channel to a corresponding data signal.

8. The system for electrically stimulating sensory nerves in the cochlea as set forth in claim 7 wherein said signal receiving means of said ICS further includes ICS processor means for processing the data signals for each of the plurality of channels and controlling the coupling means of said ICS as a function thereof.

9. The system for electrically stimulating sensory nerves in the cochlea as set forth in claim 8 wherein said power receiving means further includes regulator means for converting the dc power obtained from the implantable receiver circuit means to at least one operating voltage that is used to power said ICS, including said ICS processor means.

10. The system for electrically stimulating sensory nerves in the cochlea as set forth in claim 9 wherein said feedback means includes first and second feedback means, said first feedback means including means for generating a voltage reference signal and means for comparing the at least one operating voltage generated by said regulator means with the voltage reference signal, and generating an error signal as a function of the difference between said at least one operating voltage and said voltage reference signal, said error signal being applied to said regulator means to control the value of said at least one operating voltage;

and said second feedback means comprises means for generating a specific data signal that is transmitted back to said wearable speech processor through said transmitting means, said wearable speech processor including means for adjusting the amount of power contained within said power signal as a function of said specific data signal.

11. The system for electrically stimulating sensory nerves in the cochlea as set forth in claim 8 wherein the data signals that control said coupling means include an initialization data signal, transmitted to said ICS from said wearable speech processor, and means for preventing any of said cochlea-stimulating electrodes from being connected to its respective storage means unless the initialization data signal contains a correct initial data code.

12. The system for electrically stimulating sensory nerves in the cochlea as set forth in claim 11 wherein the number of cochlea-stimulating electrodes comprises at least sixteen.

13. The system for electrically stimulating sensory nerves in the cochlea as set forth in claim 8 further including an indifferent electrode coupled to said ICS and means for selectively connecting the indifferent electrode in circuit relationship with said cochlea-stimulating electrodes, as controlled by said ICS processor means, so that any of the plurality of cochlea-stimulating electrodes can be made to operate in a unipolar configuration with said indifferent electrode.

14. The system for electrically stimulating sensory nerves in the cochlea as set forth in claim 8 wherein said ICS further includes means for controlling the polarity and amplitude of the current sourced from the storage means through said coupling means to a selected one of said plurality of cochlea-stimulating electrodes as a function of the data signals present within a corresponding one of the plurality of data channels.

15. The system for electrically stimulating sensory nerves in the cochlea as set forth in claim 8 wherein said ICS further includes command decoder means for decoding the data signals of said plurality of data channels and generating appropriate control signals for controlling the operation of said coupling means, whereby each of said cochlea-stimulating electrodes is controlled by said control signals.

16. The system for electrically stimulating sensory nerves in the cochlea as set forth in claim 15 wherein said ICS further includes output mode register means for storing select control signals that define whether said coupling means selects one of a bipolar or unipolar mode of operation, a bipolar mode of operation comprising a mode wherein an electrical current is delivered through a select one of said cochlea-stimulating electrodes and returned through another of said cochlea-stimulating electrodes, and a unipolar mode of operation comprising a mode wherein an electrical current is delivered through a select one of said cochlea-stimulating electrodes and returned through said indifferent electrode.

17. The system for electrically stimulating sensory nerves in the cochlea as set forth in claim 15 further including multiple chip control means responsive to select control signals for generating control signals that enable said multiple chip control means to act as a master control means for controlling a plurality of identical slave control means also included within said ICS, wherein each of said slave control means is connected to a respective plurality of additional cochlea-stimulating electrodes, whereby a multiplication of the number of cochlear-stimulating electrodes that may be controlled by said ICS is provided.

18. A system for electrically stimulating sensory nerves in the cochlea comprising:

a wearable processor comprising means for sensing external audio stimuli and generating a plurality of data signals in response thereto;

a headpiece electrically connected to said wearable processor, said headpiece including a transmitting coil and a receiving coil;

said wearable processor including means for generating a power signal that is modulated by said data signals, thereby producing a modulated power signal, and means for transmitting said modulated power signal through said transmitting coil to an implantable receiver coil;

said wearable processor further including means for demodulating a telemetry signal received through said receiving coil in order to extract informational signals therefrom, said wearable processor further including means for responding to said informational signals so as to adaptively modify said data signals and power signal; and

an implantable cochlear stimulator (ICS) that includes;

receiver means for receiving said modulated power signal, said receiver means including said implantable receiver coil;

data recovery means coupled to said receiver means for recovering the data signals that modulate said modulated power signal;

power supply means coupled to said receiver means for recovering power contained within said modulated power signal and generating a plurality of operating voltages therefrom, said plurality of operating voltages providing power for the operation of said ICS;

an intracochlear electrode array comprising a plurality of cochlea-stimulating electrodes;

a plurality of output stage means, each comprising a storage capacitor, a current source connected to the storage capacitor, an electrode switching matrix, means responsive to a set of control signals for connecting the current source through the electrode switching matrix to at least one of the cochlea-stimulating electrodes included within said intracochlear electrode, and means for storing an isolated electrical charge on said storage capacitor, said stored electrical charge being obtained from said power supply, said current source including means for generating an electrical current of a specified amplitude and polarity as a function of the set of control signals;

command decoder means for generating said set of control signals as a function of select data signals recovered by said data recovery means, which recovered data signals correspond to the data signals generated by said wearable processor, which data signals, in turn, are generated as a function of the sensed audio stimuli, whereby the cochlea-stimulating electrodes have electrical currents of a specified amplitude and polarity applied thereto as a function of the sensed audio stimuli;

back telemetry means for sensing specified operating parameters associated with said power supply means, plurality of output stage means, and command decoder means, and for generating said informational signals as a function thereof, and further for generating said telemetry signal, modulating said telemetry signal with said informational signals, and transmitting said telemetry signal back to the receiving coil included within said headpiece.

19. The system for electrically stimulating sensory nerves in the cochlea as set forth in claim 18 further including a log digital/analog converter means coupled to said polarity and amplitude control means for controlling the amplitude of the electrical current applied to said cochlea-stimulating electrodes in a logarithmic manner.

20. The system for electrically stimulating sensory nerves in the cochlea as set forth in claim 18 wherein said ICS further includes an indifferent electrode and an output mode register means for storing select control signals that define whether said output stage means are to operate in a select one of a bipolar or unipolar mode of operation, a bipolar mode of operation comprising a mode wherein an electrical current is delivered through a select one of said cochlea-stimulating electrodes and returned through another of said cochlea-stimulating electrodes, and a unipolar mode of operation comprising a mode wherein an electrical current is delivered through a select one of said cochlea-stimulating electrodes and returned through said indifferent electrode, and wherein the electrode switching matrix of said output stage means includes means responsive to the control signals in said output mode register means for connecting the cochlea-stimulating electrodes to operate in a specified one of the unipolar or bipolar mode.

21. The system for electrically stimulating sensory nerves in the cochlea as set forth in claim 18 wherein said ICS further includes an initialization and status control means for receiving power from the power supply means and establishing control conditions for the ICS upon system startup and upon detection of specified system operating errors.