Multichannel cochlear prosthesis with flexible control of stimulus waveforms

• US 6,002,966 A
• Filed: 10/24/1997
• Issued: 12/14/1999
• Est. Priority Date: 04/26/1995
• Status: Expired due to Term

• Current Assignee: Advanced Bionics AG (Sonova Holding AG)
• Original Assignee: Advanced Bionics Corporation (Sonova Holding AG)
• Inventors: Faltys, Michael A., Loeb, Gerald E.
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): LAYNO, CARL HERNANDZ
• Application Number:
  US08/945,661
• Time in Patent Office: 781 Days
• Field of Search: 607/55-57
• US Class Current: 607/57
• CPC Class Codes: A61N 1/36038 Cochlear stimulation

Abstract

A method and system provides a wide range of temporospatial patterns of electrical stimulation waveforms to be readily specified for respective channels of a multichannel cochlear prosthesis. The cochlear prosthesis includes a speech processor system and a cochlear stimulator. The speech processor system typically includes an external headpiece, including a microphone, coupled to a speech processor. The speech processor includes electronic circuitry, typically including a microprocessor, that converts acoustical signals sensed through the microphone to electrical signals, and processes the electrical signals in accordance with a desired speech processing strategy. The definition of simple or complex stimulation waveforms to be used as part of the selected speech processing strategy is facilitated, in a preferred embodiment, through the use of a template table stored in the speech processor. The rows and columns of the template table define time intervals and stimulation channels (and hence stimulation sites). The individual cells of the template table are programmed, e.g., using a laptop computer, to contain selected alphanumeric codes or characters, including null characters, that define the polarity and relative magnitude of desired stimulation patterns and waveforms that are applied to the defined stimulation sites at the indicated frame times. Alternatively, the stimulation patterns and waveforms may be specified in a list of spatial/temporal events.

Claims

1. A method of controlling a cochlear stimulator (CS), said CS including a multiplicity of channels, each channel having at least one pair of stimulation electrodes associated therewith and means for generating and applying a stimulation pulse thereto;

and means for defining a data frame that defines a time period during which the multiplicity of channels are stimulated in accordance with a prescribed pattern;

said method comprising the steps of;

(a) specifying a particular type of stimulation waveform that is desired for each channel of the CS during each data frame, the type of stimulation waveform specified for one channel being independent of the type of stimulation waveforms specified for others of the channels, whereby each channel has its own stimulation waveform specified therefor, which stimulation waveform need not be the same as the stimulation waveform specified for another channel, but can be when desired, said specifying the type of stimulation waveform comprising;

(1) generating and storing for use by the CS a table having rows and columns, each column or row being associated with one of the multiplicity of channels, and each row or column being associated with an increment of time equal to a duration of the narrowest pulse width to be included within the stimulation waveform, with the sum of the time increments from all of the rows/columns of the table equaling the time period of a data frame, and wherein the intersection of each row and column comprises a table cell, and

(2) inserting an alphanumeric value in the cell of the table that defines the desired relative amplitude and polarity of the stimulus waveform for the channel and frame time corresponding to the table cell, whereby the temporospatial pattern of stimulus waveforms specified for a given channel is defined by the sequence of alphanumeric values inserted in the column/row of the table corresponding to the given channel, and

(3) interpreting a designated alphanumeric character in a given table cell as specifying that no change is required in the output of the channel corresponding to the column/row of the given table cell containing the designated alphanumeric character at the frame time corresponding to the row/column of the given table cell containing the designated alphanumeric character;

(b) generating and transmitting a control signal to the CS that defines the particular type of stimulation waveform desired for each channel of the ICS; and

(c) generating the stimulation waveform specified by the control signal for each channel of the ICS during each data frame.

2. The method of claim 1 further including the step of shortening the frame time by an amount equal to the number of cells in a given row or column of the table that contain nothing but the designated alphanumeric character.

3. A stimulation prosthesis system comprising:

an implantable stimulator having a multiplicity of electrode pairs, means for receiving control signals, and means responsive to receiving the control signals for generating a multiplicity of temporospatial patterns of stimulus waveforms that are applied to said electrode pairs;

a speech processor including means for generating and coupling the control signals to the implantable stimulator, and means for specifying within the control signals a particular temporospatial pattern of stimulus waveforms for application to each of the multiplicity of electrode pairs;

the speech processor further including means for controlling a cycle rate associated with the stimulation of at least one of the multiplicity of electrode pairs, wherein the cycle rate comprises the rate at which the particular temporospatial pattern of stimulus waveforms is applied to the at least one of the multiplicity of electrode pairs; and

the speech processor also including means for defining at least one virtual channel that sets the temporospatial pattern of the at least one virtual channel as a function of the temporospatial patterns of adjacent channels.

4. A method of defining the stimulation current to be applied by a cochlear stimulator (CS) on each of a multiplicity of channels, each channel having at least one pair of stimulation electrodes associated therewith to which the defined stimulation current is applied, the method comprising:

(a) defining a data frame as a time period during which the multiplicity of channels are stimulated in accordance with a prescribed pattern of the stimulation current;

(b) storing data that defines a particular type of stimulation waveform desired for each channel of the CS during each data frame, the type of stimulation waveform including a specification of a stimulation pulse polarity, duration and time of occurrence within the data frame, the type of stimulation waveform specified for one channel being independent of the type of stimulation waveforms specified for others of the channels, whereby each channel has its own stimulation waveform specified therefor, which stimulation waveform need not be the same as the stimulation waveform specified for another channel, but can be when desired;

(c) processing sensed sound signals in accordance with a selected speech processing strategy; and

(d) presenting the data stored in step (b) and the processed sound signals of step (c) to the CS to cause the defined stimulation waveform to be applied to the at least one pair of stimulation electrodes of each channel, the stimulation waveform being of a type as defined by the data stored in step (b) and having an amplitude determined in part by the processed sound signals.

5. The method of claim 4 wherein step (b) further includes utilizing a weighting factor that specifies how much weight is to be given to the processed sensed sound signals.

6. The method of claim 5 wherein the weighting factor comprises a multiplication factor having a polarity, and wherein the method further comprises multiplying the multiplication factor and the processed sensed sound signal to produce a product, the product serving to define the amplitude of the stimulation current to be applied to the electrode pair.

7. The method of claim 4 wherein step (b) comprises:

(1) generating and storing for use by the CS a table having rows and columns, each column or row being associated with one of the multiplicity of channels, and each row or column being associated with an increment of time equal to the duration of the narrowest pulse width to be included within the stimulation waveform, with the sum of the time increments from all of the rows/columns of the table equaling the time period of a data frame, and wherein the intersection of each row and column comprises a table cell, and

(2) inserting an alphanumeric value in the cell of the table that defines the desired relative amplitude and polarity of the stimulus waveform for the channel and frame time corresponding to the table cell, whereby the temporospatial pattern of stimulus waveforms specified for a given channel is defined by the sequence of alphanumeric values inserted in the column/row of the table corresponding to the given channel.

8. The method of claim 7 further including mapping the processed sound signals from at least n+1 channels to only n pair of stimulation electrodes, thereby creating at least one virtual stimulation channel.

9. The method of claim 8 further including mapping the processed sound signals from at least n+2 channels to only n pair of stimulation electrodes, thereby creating at least two virtual stimulation channels.