Stimulation prosthesis with configurable data link

Abstract

The present application discloses systems and methods for operating a stimulation prosthesis that contains a command module and a stimulator module that communicate by a data link. The stimulation prosthesis has at least two operating states: a configuration state and a stimulation state. In one embodiment, the stimulation prosthesis may use a communication protocol that is suitable for the current operating state. The risk of unintended transitions between the operating states due to data transmission errors is substantially eliminated. And in accordance with another embodiment, in addition to switching stimulation strategies, the stimulation prosthesis may also switch stimulation data formats to a format that is optimized for the new stimulation strategy.

Description

BACKGROUND

Various types of hearing prostheses may provide persons with different types of hearing loss with the ability to perceive sound. Hearing loss may be conductive, sensorineural, or some combination of both conductive and sensorineural hearing loss. Conductive hearing loss typically results from a dysfunction in any of the mechanisms that ordinarily conduct sound waves through the outer ear, the eardrum, or the bones of the middle ear. Sensorineural hearing loss typically results from a dysfunction in the inner ear, including the cochlea where sound vibrations are converted into neural signals, or any other part of the ear, auditory nerve, or brain that may process the neural signals.

Persons with some forms of conductive hearing loss may benefit from hearing prostheses, such as acoustic hearing aids or vibration-based hearing aids. An acoustic hearing aid typically includes a small microphone to detect sound, an amplifier to amplify certain portions of the detected sound, and a small speaker to transmit the amplified sounds into the person's ear. Vibration-based hearing aids typically include a small microphone to detect sound, and a vibration mechanism to apply vibrations corresponding to the detected sound to a person's bone, thereby causing vibrations in the person's inner ear, thus bypassing the person's auditory canal and middle ear. Vibration-based hearing aids may include bone anchored hearing aids, direct acoustic cochlear stimulation devices, or other vibration-based devices. A bone anchored hearing aid typically utilizes a surgically-implanted mechanism to transmit sound via direct vibrations of the skull. Similarly, a direct acoustic cochlear stimulation device typically utilizes a surgically-implanted mechanism to transmit sound via vibrations corresponding to sound waves to generate fluid motion in a person's inner ear. Other non-surgical vibration-based hearing aids may use similar vibration mechanisms to transmit sound via direct vibration of teeth or other cranial or facial bones.

Persons with certain forms of sensorineural hearing loss may benefit from cochlear implants and/or auditory brainstem implants. For example, cochlear implants may provide a person having sensorineural hearing loss with the ability to perceive sound by stimulating the person's auditory nerve via an array of electrodes implanted in the person's cochlea. FIG. 1 depicts an example cochlear implant. The example cochlear implant includes an external sound processor 101, which is typically worn behind the ear. The cochlear implant has at least one microphone 105 that produces an audio signal 106. Sound processor 101 processes the audio signal 106 to determine an appropriate pattern of electrical stimulation to apply to the recipient of the cochlear implant.

Generally, the pattern of electrical stimulation is determined in accordance with a set of rules referred to as a sound coding strategy. Typically, the sound processor 101 transmits information specifying the desired stimulation pattern over a transcutaneous radio-frequency (RF) link 103 to an implanted stimulator module 102. The implanted stimulator module 102 generates electrical stimuli and delivers those stimuli to an array of electrodes 104, which are implanted in a recipient's cochlea. Electrically stimulating nerves in a cochlea with a cochlear implant may enable persons with sensorineural hearing loss to perceive sound.

SUMMARY

Current hearing prostheses and other stimulation prostheses suffer from several drawbacks that will be discussed herein. One drawback is that stimulator modules are typically configured with relatively simple state machines, which may limit the stimulator prosthesis to one stimulation strategy and one data protocol that it can process. Thus, configuration data and stimulation data alike are transmitted according to the same protocol. As a result, the stimulation prosthesis either uses a protocol with a high degree of error control, which is inefficient when transmitting stimulation data, or a protocol with a low degree of error control, which is dangerous insofar as the stimulation module could become configured incorrectly. In addition, if a protocol or strategy change is desired, it usually necessitates costly surgery.

To address these shortcomings, the present application discloses a stimulation prosthesis that can operate according to at least two operating states: a configuration state and a stimulation state. The stimulation prosthesis may use a data protocol that is suitable for the current operating state. For example, in one embodiment the stimulation prosthesis uses a communication protocol with a relatively high degree of error control while in the configuration state, and a communication protocol with a relatively low degree of error control while in the stimulation state.

In accordance with another embodiment, the stimulation prosthesis transitions from the stimulation state into the configuration state in order to re-program and operate according to a different stimulation strategy. The stimulation prosthesis may initiate such a transition by temporarily stopping transmission while in the stimulation state. By using the temporary stoppage of transmission as a signal to change operation states, it is less likely that a stimulation module will inadvertently transition into the configuration state and become erroneously programmed.

In accordance with another embodiment, in addition to switching stimulation strategies, the stimulation prosthesis may also switch stimulation data formats to a format that is optimized for the new stimulation strategy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of an example cochlear implant system.

FIG. 2 shows a block diagram of a general stimulation prosthesis, in accordance with one embodiment.

FIG. 3 depicts a block diagram of a stimulator module, in accordance with one embodiment.

FIGS. 4A-B depict block diagrams of stimulator modules, in accordance with some embodiments.

FIG. 5 depicts another block diagram of a stimulator module, in accordance with one embodiment.

FIG. 6 depicts a block diagram of a data link processor, in accordance with one embodiment.

FIG. 7A depicts an example timing diagram for half-duplex communication between a command module and a stimulator module, in accordance with one embodiment.

FIG. 7B depicts an example detailed timing diagram for half-duplex communication between a command module and stimulator module, in accordance with one embodiment.

FIG. 8A depicts an example timing diagram for an overall sequence of operation of a stimulation prosthesis, in accordance with one embodiment.

FIG. 8B depicts an example timing diagram for the transmission of individual frames of power-up and configuration states, in accordance with one embodiment.

FIG. 9 depicts example program code for a Boot ROM routine, in accordance with one embodiment.

FIG. 10 depicts additional example program code for a Boot ROM routine, in accordance with one embodiment.

FIG. 11 depicts example program code for the operation of a stimulation prosthesis in accordance with one embodiment.

FIGS. 12A-G depict example formats of stimulation data, in accordance with several embodiments.

FIGS. 13A-F depict additional example program code for the operation of a stimulation prosthesis in accordance with several embodiments.

FIG. 14 depicts an example phase diagram, in accordance with one embodiment.

FIG. 15 depicts another example phase diagram, in accordance with one embodiment.

FIG. 16 depicts yet another example phase diagram, in accordance with one embodiment.

FIG. 17 depicts example program code for the operation of a stimulation prosthesis in accordance with one embodiment.

FIG. 18 depicts example program code for the operation of a stimulation prosthesis in accordance with one embodiment.

DETAILED DESCRIPTION

The following detailed description describes various features and functions of the disclosed systems and methods with reference to the accompanying figures. In the figures, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative system and method embodiments described herein are not meant to be limiting. Certain aspects of the disclosed systems and methods can be arranged and combined in a wide variety of different configurations, all of which are contemplated herein.

Certain aspects of the disclosed systems, methods, and articles of manufacture may be described herein with reference to cochlear implant and acoustic hearing aid embodiments. However, the disclosed systems, methods, and articles of manufacture are not so limited. Many of the disclosed features and functions described with respect to the cochlear implant and acoustic hearing aid embodiments may be equally applicable to other embodiments that may include other types of hearing prostheses, such as, for example, bone anchored hearing aids, direct acoustic cochlear stimulation devices, auditory brain stem implants, or any other type of hearing prosthesis that may be configured to transmit data across a data link.

Moreover, many of the disclosed features and functions may also be applicable to prostheses that use both electrical and acoustic stimulation, sometimes referred to as hybrid devices, and to hearing prostheses that use mechanical stimulation. Further, many of the disclosed features and functions can be applied to any general stimulation prosthesis that includes a data link over which the prosthesis transmits data.

Stimulation Prosthesis Overview

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where lower_level is the lowest amplitude delivered on that channel, and generally corresponds to the recipient's threshold; upper_level is the highest amplitude delivered on that channel, and generally corresponds to the recipient's maximum comfortable level; and magnitude is derived from the amplitude of the signal in the corresponding filter (after non-linear compression) and has a value in the range zero to one. This formula can also be expressed as:
amplitude=lower_level+height,
where height is given by the expression:
height=(upper_level−lower_level)*magnitude.
The majority of recipients have a range between lower_level and upper_level which is less than 64 discrete values. Thus, a further reduction in data rate can be obtained if the command module specifies a pulse by its height rather than its amplitude.

FIG. 13C shows an example program code 1304 used by the data link processor 310 referred to as the Stim_chan_height routine. This program code implements the channel-height data format. The configuration parameter num_pulses specifies the number of pulses per packet. The configuration parameter num_bits_height specifies the number of bits used to represent the height of each pulse. This is generally fewer than 8, and is typically 6. The configuration parameter num_bits_channel specifies the number of bits used to represent the channel index. The value 4 allows up to 16 channels; the value 5 allows up to 32 channels, and so on. The configuration parameter b_lower_level specifies the memory bank that holds a table containing the value of lower_level for each channel. This table may be down-loaded into RAM during configuration. In the inner loop, the C register receives the channel number. The C register is used to index into the lower_level table in the ADD instruction, a +=m[bc], and also specifies the channel for the PULSE instruction (as described in other stimulation routines). If this format is used in conjunction with the SPEAK or ACE strategies for example, then it is convenient for the number of pulses in each packet to be equal to the number of maxima.

A corresponding example packet with num_pulses=8, num_bits_height=6, and num_bits_channel=5 is depicted in FIG. 12D. It occupies 7 frames, and contains 3 extra bits, so the Check_header routine would be inserted after the Stim_chan_height label (not shown in the program code 1304 for brevity). With the timing given in FIG. 7B,
A correct 8-bit result is produced because the A register has 9 bits. The routine then outputs a pulse with the interpolated amplitude.

Each iteration of the second loop Loop_output_latest copies a value from the b_latest_amplitude buffer to the b_previous_amplitude buffer, and outputs a pulse having the latest amplitude (i.e., a pulse derived from the data in the latest packet). During configuration, the b_previous_amplitude buffer is initialized to equal the b_lower_level table. With the timing given in FIG. 7B, this configuration has a packet duration of about 146.4 microseconds, which yields a pulse rate of twice that of the Stim_height_vector_routine—about 109,200 pps.

A stimulation strategy that incorporates high-rate “conditioning pulses” may have some benefit. In such a strategy, pulses can be (i) information pulses, which are derived from the audio signal, or (ii) conditioning pulses, which do not carry any information, have fixed amplitude, and are delivered at a high rate. In one embodiment, information pulses and conditioning pulses are delivered to the same electrode in alternating time windows. In some stimulation prosthesis systems, every pulse requires a certain amount of data to be transmitted across the data link, which may limit the rate of the conditioning pulses.

Instead, by way of the data link processor 310 it may be advantageous to generate the conditioning pulses within the stimulator module itself. Therefore, in some embodiments, the data link processor generates such conditioning pulses autonomously. FIG. 18 shows an example program code 1800 referred to as the Stim_height_vector_conditioner routine and used by data link processor 310. It uses the height-vector format defined previously. This routine uses the height-vector format as previously defined and depicted in FIG. 12E. To reiterate, this is a packet with num_channels=8 and num_bits_height=6. It occupies 4 frames, and contains 4 extra bits, so the Check_header routine would be inserted after the Stim_interpolate_vector label (not shown in program code 1800 for brevity).

The first part of the routine contains a nested loop. The inner loop, labeled Loop_conditioner_pulse, outputs one conditioner pulse on each electrode, with amplitudes taken from the configuration table b_condition_level. The configuration parameter num_conditioners specifies the number of times the outer loop, Loop_conditioner_scan, is executed. For example, if num_conditioners is set to two, then there will be two iterations of the outer loop, producing two conditioning scans across the electrode array. The final loop, labeled Information_pulse, produces one information pulse on each electrode.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Claims

1. A stimulator module comprising:

a receiver configured for receiving data that is transmitted by a command module across a data link, wherein the received data includes stimulation data and configuration data; and

a data link processor configured for operating any one of at least two states, wherein:

the at least two states comprise a stimulation state and a configuration state;

operating in the stimulation state comprises generating one or more stimulation pulses by processing the stimulation data according to one of (i) a first stimulation protocol, the first stimulation protocol defining at least a first format of stimulation data for implementing a first stimulation strategy for stimulating one or more channels of the stimulation module, or (ii) a second stimulation protocol, the second stimulation protocol defining at least a second format of stimulation data for implementing a second stimulation strategy for stimulating one or more channels of the stimulation module, wherein the first stimulation strategy and the second stimulation strategy are different stimulation strategies;

processing stimulation data according to the first stimulation strategy comprises the data link processor (a) processing the received data to determine an amplitude for each of M channels of the stimulation module, (b) based on the determined amplitudes, selecting N of the M channels based on an N-of-M stimulation strategy, and (c) for each of the N selected channels, generating one of the one or more stimulation pulses, wherein N and M are positive integers and M is greater than N;

operating in the configuration state comprises processing the configuration data according to a configuration protocol, wherein the configuration data includes instructions for processing the stimulation data according to one of the first stimulation protocol or the second stimulation protocol, and

the first stimulation protocol, the second stimulation protocol, and the configuration protocol are different protocols.

2. The stimulator module of claim 1, wherein:

the configuration data includes an indication of a conditioning level,

the stimulator module is further configured to apply conditioning pulses to at least some stimulation channels between application of successive electric signals to the stimulation channels, and

the conditioning pulses have an amplitude about equal to the conditioning level.

3. The stimulator module of claim 1, wherein a stimulation rate of the stimulation module depends at least in part on whether the data link processor processes stimulation data according to (a) the first stimulation protocol or (b) the second stimulation protocol.

4. The stimulation module of claim 3, wherein the stimulation rate is greater when the data link processor processes stimulation data according to the first stimulation protocol than when the data link processor processes stimulation data according to the second stimulation protocol.

5. The stimulator module of claim 1, wherein, for a given set of stimulation data, a number of channels stimulated by the stimulation module depends at least in part on whether the data link processor processes stimulation data according to (a) the first stimulation protocol or (b) the second stimulation protocol.

6. The stimulation module of claim 5, wherein the number of channels is greater when the data link processor processes stimulation data according to the first stimulation protocol than when the data link processor processes stimulation data according to the second stimulation protocol.

7. The stimulation module of claim 1, wherein the configuration protocol has a higher degree of error control than either the first stimulation protocol or the second stimulation protocol.

8. The stimulation module of claim 1, wherein the second stimulation protocol comprises implementing an interpolation technique, and wherein, to implement the interpolation technique, the data link processor is further configured for:

determining a plurality of stimulation values included in a set of processed stimulation data; and

determining, for at least one stimulation channel of the stimulation module, an amplitude of an electrical signal by interpolating between any two individual amplitude values in the plurality of amplitude values.

9. The stimulation module of claim 1, wherein the N-of-M strategy is an advanced combination encoder strategy for stimulating the one or more channels.

10. The stimulation module of claim 1, wherein the N-of-M strategy is a spectral peak strategy for stimulating the one or more channels.

11. The stimulation module of claim 1, wherein the data link processor is further configured for, prior to processing the configuration data:

(a) operating the stimulation module in the stimulation state;

(b) determining that the stimulation data is not received within a period of time after receiving previous stimulation data; and

(c) responsive to the determining, operating the stimulation module in the configuration state.

12. The stimulation module of claim 1, wherein operating in the stimulation state further comprises processing additional stimulation data according to one or more additional stimulation protocols, wherein the one or more additional stimulation protocols differ from each of the first stimulation protocol and the second stimulation protocol.

13. A hearing prosthesis, comprising:

a stimulator module configured to generate stimulation signals for delivery to a recipient of the hearing prosthesis; and

a command module configured to send configuration data and stimulation data to the stimulator module via a data link, and

wherein the command module is configured to use a first communication protocol to send the configuration data to the stimulator module and to use a second communication protocol to send the stimulation data to the stimulator module, and wherein the first and second communication protocols are different from one another,

wherein the first communication protocol has a higher degree of error control than the second communication protocol.

14. The hearing prosthesis of claim 13, wherein the stimulation signals are based on a received audio signal, and wherein the stimulation data comprises parameters of the stimulation signals that vary dynamically according to the received audio signal.

15. The hearing prosthesis of claim 13, wherein the stimulation signals are based on a received audio signal, and wherein the configuration data comprises parameters of the stimulation signals that do not vary dynamically according to the received audio signal.

16. The hearing prosthesis of claim 13, wherein the data link is a wireless link.

17. The hearing prosthesis of claim 16, wherein the data link is a transcutaneous radio frequency (RF) inductive link.

18. The hearing prosthesis of claim 13, wherein the command module and the stimulator module are implantable in the recipient.

19. The hearing prosthesis of claim 13, wherein the command module is an external component configured to he worn by the recipient.

20. A method, comprising:

sending, via a data link, configuration data from a command module to a stimulator module of a hearing prosthesis using a first communication protocol; and

sending, via the data link, stimulation data from the command module to the stimulator module using a second communication protocol,

wherein the first and second communication protocols are different from one another and wherein the first communication protocol has a higher degree of error control than the second communication protocol.

21. The method of claim 20, comprising:

detecting absence of stimulation data across the data link for a predetermined duration of time; and

based on the absence of stimulation data for a predetermined duration of time, determining a reconfiguration of the stimulator module.

22. The method of claim 20, wherein the first communication protocol and the second communication protocol have different data formats.

23. A method, comprising:

sending, via a data link, first stimulation data for a first sound coding strategy from a command module to a stimulator module of a hearing prosthesis using a first communication protocol;

generating, at the stimulator module, first stimulation pulses for delivery to a recipient of the hearing prosthesis using the first stimulation data;

determining, at the command module, a reconfiguration of the stimulator module for use of a second sound coding strategy that is different from the first sound coding strategy;

sending, via the data link, second stimulation data for a second sound coding strategy from the command module to the stimulator module using a second communication protocol that is different from the first communication protocol; and

generating, at the stimulator module, second stimulation pulses for delivery to the recipient of the hearing prosthesis using the second stimulation data.

24. The method of claim 23, wherein the first communication protocol and the second communication protocol have different data formats.

25. The method of claim 23, wherein determining a reconfiguration of the stimulator module comprises:

sending, via the data link, configuration data identifying the second sound coding strategy; and

initiating the second sound coding strategy at the stimulator module.

26. The method of claim 25, wherein prior to receiving the configuration data, the method comprises:

detecting absence of first stimulation data across the data link for a predetermined duration of time;

in response to detecting the absence of the first stimulation data for the predetermined duration of time, initiating a reset of internal registers in the stimulator module; and initiating a configuration state at the stimulator module.

27. The method of claim 25, wherein sending the configuration data identifying the second sound coding strategy comprises:

sending the configuration data using a third communication protocol that is different from the first and second communication protocols.

28. The method of claim 27, wherein the third communication protocol has a higher degree of error control than either the first or second communication protocols.

29. A hearing prosthesis, comprising:

a stimulator module configured to generate stimulation signals for delivery to a recipient of the hearing prosthesis, wherein the stimulator module is configured to generate the stimulation signals according to a current sound coding strategy, wherein the current sound coding strategy is selected from among a plurality of different sound coding strategies; and

a command module configured to send stimulation data to the stimulator module via a data link, wherein the stimulation data is sent using a communication protocol that varies based on the current sound coding strategy of the stimulator module.

30. The hearing prosthesis of claim 29, wherein the plurality of different sound coding strategies comprise at least a first and second sound coding strategies, wherein during a first time period the stimulator module generates first stimulation pulses for delivery to a recipient of the hearing prosthesis using the first sound coding strategy and the during a second time period the stimulator module generates second stimulation pulses for delivery to a recipient of the hearing prosthesis using the second sound coding strategy.

31. The hearing prosthesis of claim 30, wherein during the first time period the command module is configured to send first stimulation data to the stimulator module using a first communication protocol, and during the second time period the command module is configured to send second stimulation data to the stimulator module using a second communication protocol that is different from the first communication protocol.

32. The hearing prosthesis of claim 31, wherein the first stimulation data and the second stimulation data are each based on received audio signals, and wherein the first stimulation data and the second stimulation data each comprises parameters of the first and second stimulation pulses, respectively, that vary dynamically according to the received audio signals.

33. The hearing prosthesis of claim 29, wherein a data format of the communication protocol varies based on the current sound coding strategy of the stimulator module.

34. A hearing prosthesis, comprising: a command module; a stimulator module, comprising:

a receiver configured to receive data transmitted across a data link from a command module; and

a data link processor configured to operate the stimulator module in first and second operating states, wherein the first operating state of the stimulator module is a configuration state in which data received by the receiver via the data link is configuration data and the second operating state of the stimulator module is a stimulation state in which data received by the receiver is stimulation data for use in generating stimulation signals for delivery to a recipient and

wherein the configuration data is sent by the command module using a first communication protocol and the stimulation data is sent by the command module using a second communication protocol, and wherein the first communication protocol has a higher degree of error control than the second communication protocol.

35. The hearing prosthesis of claim 34, wherein first state of the stimulator module is a first stimulation state in which the stimulator module receives first stimulation data via the data link and generates first stimulation pulses from the first stimulation data according to a first sound coding strategy, and wherein the second state of the stimulator module is a second stimulation state in which the stimulator module receives second stimulation data via the data link and generates second stimulation pulses from the second stimulation data according to a second sound coding strategy.

36. The hearing prosthesis of claim 35, wherein the first stimulation data is sent by the command module using a first communication protocol and the second stimulation data is sent by the command module using a second communication protocol that is different from the first communication protocol.

37. The hearing prosthesis of claim 36, wherein the first communication protocol and the second communication protocol have different data formats.