Patent Description:
The invention relates to a system for monitoring of evoked responses that occur during an electrode lead insertion procedure as defined in claim <NUM>. For example, a diagnostic system may determine a minimum evoked response amplitude and a maximum evoked response amplitude for a recipient of a cochlear implant. The diagnostic system may determine a mapping between a plurality of audible pitches and a plurality of evoked response amplitudes included in a range defined by the minimum and maximum evoked response amplitudes. The diagnostic system may monitor, during an insertion procedure in which an electrode lead communicatively coupled to the cochlear implant is inserted into a cochlea of the recipient, an evoked response signal recorded during the insertion procedure by an electrode disposed on the electrode lead. The evoked response signal represents amplitudes of a plurality of evoked responses that occur within the recipient in response to acoustic stimulation applied to the recipient. The evoked responses may each be an ECoG potential (e.g., a cochlear microphonic potential, an action potential, a summating potential, etc.), an auditory nerve response, a brainstem response, a compound action potential, a stapedius reflex, and/or any other type of neural or physiological response that may occur within a recipient in response to application of acoustic stimulation to the recipient. Evoked responses may originate from neural tissues, hair cell to neural synapses, inner or outer hair cells, or other sources.

As the evoked response signal is being monitored, the diagnostic system may detect an amplitude change in the evoked response signal and present, based on the mapping, acoustic feedback that audibly indicates the amplitude change.

To illustrate, the mapping may specify that a first audible pitch is mapped to a first evoked response amplitude and that a second audible pitch is mapped to a second evoked response amplitude that is different than the first evoked response amplitude. During the insertion procedure, the diagnostic system may direct an acoustic stimulation generator to apply acoustic stimulation to the recipient. The diagnostic system may detect a first evoked response that occurs at a first time within the recipient in response to the acoustic stimulation (e.g., by directing the cochlear implant to use the electrode disposed on the electrode lead to detect the first evoked response). In response to detecting the first evoked response, the diagnostic system may present, based on the mapping, acoustic feedback (e.g., an audible tone) that has the first audible pitch to a user of the diagnostic system. The diagnostic system may direct the acoustic stimulation generator to continue applying the acoustic stimulation to the recipient. As the electrode lead is inserted further into the cochlea, the diagnostic system may detect a second evoked response that occurs at a second time within the recipient in response to the acoustic stimulation. In response to detecting the second evoked response, the diagnostic system may present, based on the mapping, acoustic feedback that has the second audible pitch to the user of the diagnostic system.

In some examples, the systems and methods described herein are implemented by a stand-alone diagnostic system that includes a computing module and a base module configured to attach to the computing module (e.g., a back side of the computing module) and serve as a stand for the computing module. The computing module includes a display screen and a processor configured to direct the display screen to display a graphical user interface. The base module houses an interface unit configured to be communicatively coupled to the processor and to a cochlear implant while the base module is attached to the computing module. In this configuration, the processor may be configured to detect a request to begin monitoring an evoked response signal associated with a recipient of the cochlear implant during an insertion procedure in which an electrode lead is inserted into a cochlea of the recipient. In response to the request, the processor may direct the interface unit to apply acoustic stimulation to the recipient by way of a sound delivery apparatus coupled to the base module and direct the cochlear implant to record the evoked response signal using an electrode disposed on the electrode lead. In response to detecting an amplitude change in the evoked response signal, the processor may present acoustic feedback that audibly indicates the amplitude change.

By providing acoustic feedback that audibly indicates amplitude changes in the evoked response signal recorded by the electrode during the electrode lead insertion procedure, the systems and methods described herein may advantageously allow a surgeon or other user involved with the insertion procedure to readily ascertain various characteristics and/or events associated with the insertion procedure without having to look at a display screen that shows information associated with the insertion procedure. This may allow the surgeon to focus his or her visual attention on the insertion procedure itself (e.g., by focusing his or her eyes on a surgical scope) while still receiving feedback representative of the characteristics and/or events associated with the insertion procedure.

For example, during an electrode lead insertion procedure, relatively low frequency (e.g., <NUM>) acoustic stimulation may be applied to the recipient. This relatively low frequency corresponds to a location that is relatively deep within the cochlea (i.e., close to the apex of the cochlea). As such, as the surgeon advances the electrode lead further into the cochlea, the evoked response amplitude recorded by the electrode on the electrode lead will increase as long as the electrode lead is being properly advanced within the cochlea. The audible pitch of the acoustic feedback may correspondingly increase, thereby indicating to the surgeon that the electrode lead is being properly advanced within the cochlea. However, at some point, the electrode lead may damage a wall or other structure of the cochlea. This may cause the evoked responses detected by the electrode on the electrode lead to suddenly decrease in amplitude. A corresponding decrease in audible pitch of the acoustic feedback being presented by the diagnostic system to the surgeon (and, in some, examples, an additional type of acoustic feedback is presented that does not include any of the audible pitches used in the mapping) may immediately make the surgeon aware of this sudden decrease in evoked response amplitude. The surgeon may then take remedial action (e.g., by stopping the lead insertion, repositioning or redirecting the electrode lead within the cochlea, etc.).

<FIG> illustrates an exemplary cochlear implant system <NUM>. As shown, cochlear implant system <NUM> may include a microphone <NUM>, a sound processor <NUM>, a headpiece <NUM> having a coil disposed therein, a cochlear implant <NUM>, and an electrode lead <NUM>. Electrode lead <NUM> may include an array of electrodes <NUM> disposed on a distal portion of electrode lead <NUM> and that are configured to be inserted into a cochlea of a recipient to stimulate the cochlea when the distal portion of electrode lead <NUM> is inserted into the cochlea. One or more other electrodes (e.g., including a ground electrode, not explicitly shown) may also be disposed on other parts of electrode lead <NUM> (e.g., on a proximal portion of electrode lead <NUM>) to, for example, provide a current return path for stimulation current generated by electrodes <NUM> and to remain external to the cochlea after electrode lead <NUM> is inserted into the cochlea. As shown, electrode lead <NUM> may be pre-curved so as to properly fit within the spiral shape of the cochlea. Additional or alternative components may be included within cochlear implant system <NUM> as may serve a particular implementation.

As shown, cochlear implant system <NUM> may include various components configured to be located external to a recipient including, but not limited to, microphone <NUM>, sound processor <NUM>, and headpiece <NUM>. Cochlear implant system <NUM> may further include various components configured to be implanted within the recipient including, but not limited to, cochlear implant <NUM> and electrode lead <NUM>.

Microphone <NUM> may be configured to detect audio signals presented to the user. Microphone <NUM> may be implemented in any suitable manner. For example, microphone <NUM> may include a microphone that is configured to be placed within the concha of the ear near the entrance to the ear canal, such as a T-MIC™ microphone from Advanced Bionics. Such a microphone may be held within the concha of the ear near the entrance of the ear canal during normal operation by a boom or stalk that is attached to an ear hook configured to be selectively attached to sound processor <NUM>. Additionally or alternatively, microphone <NUM> may be implemented by one or more microphones disposed within headpiece <NUM>, one or more microphones disposed within sound processor <NUM>, one or more beam-forming microphones, and/or any other suitable microphone as may serve a particular implementation.

Sound processor <NUM> may be configured to direct cochlear implant <NUM> to generate and apply electrical stimulation (also referred to herein as "stimulation current") representative of one or more audio signals (e.g., one or more audio signals detected by microphone <NUM>, input by way of an auxiliary audio input port, input by way of a clinician's programming interface (CPI) device, etc.) to one or more stimulation sites associated with an auditory pathway (e.g., the auditory nerve) of the recipient. Exemplary stimulation sites include, but are not limited to, one or more locations within the cochlea, the cochlear nucleus, the inferior colliculus, and/or any other nuclei in the auditory pathway. To this end, sound processor <NUM> may process the one or more audio signals in accordance with a selected sound processing strategy or program to generate appropriate stimulation parameters for controlling cochlear implant <NUM>. Sound processor <NUM> may be housed within any suitable housing (e.g., a behind-the-ear ("BTE") unit, a body worn device, headpiece <NUM>, and/or any other sound processing unit as may serve a particular implementation).

In some examples, sound processor <NUM> may wirelessly transmit stimulation parameters (e.g., in the form of data words included in a forward telemetry sequence) and/or power signals to cochlear implant <NUM> by way of a wireless communication link <NUM> between headpiece <NUM> and cochlear implant <NUM> (e.g., a wireless link between a coil disposed within headpiece <NUM> and a coil physically coupled to cochlear implant <NUM>). It will be understood that communication link <NUM> may include a bi-directional communication link and/or one or more dedicated uni-directional communication links.

Headpiece <NUM> may be communicatively coupled to sound processor <NUM> and may include an external antenna (e.g., a coil and/or one or more wireless communication components) configured to facilitate selective wireless coupling of sound processor <NUM> to cochlear implant <NUM>. Headpiece <NUM> may additionally or alternatively be used to selectively and wirelessly couple any other external device to cochlear implant <NUM>. To this end, headpiece <NUM> may be configured to be affixed to the recipient's head and positioned such that the external antenna housed within headpiece <NUM> is communicatively coupled to a corresponding implantable antenna (which may also be implemented by a coil and/or one or more wireless communication components) included within or otherwise associated with cochlear implant <NUM>. In this manner, stimulation parameters and/or power signals may be wirelessly transmitted between sound processor <NUM> and cochlear implant <NUM> via communication link <NUM>.

Cochlear implant <NUM> may include any suitable type of implantable stimulator. For example, cochlear implant <NUM> may be implemented by an implantable cochlear stimulator. Additionally or alternatively, cochlear implant <NUM> may include a brainstem implant and/or any other type of cochlear implant that may be implanted within a recipient and configured to apply stimulation to one or more stimulation sites located along an auditory pathway of a recipient.

In some examples, cochlear implant <NUM> may be configured to generate electrical stimulation representative of an audio signal processed by sound processor <NUM> (e.g., an audio signal detected by microphone <NUM>) in accordance with one or more stimulation parameters transmitted thereto by sound processor <NUM>. Cochlear implant <NUM> may be further configured to apply the electrical stimulation to one or more stimulation sites (e.g., one or more intracochlear regions) within the recipient via electrodes <NUM> disposed along electrode lead <NUM>. In some examples, cochlear implant <NUM> may include a plurality of independent current sources each associated with a channel defined by one or more of electrodes <NUM>. In this manner, different stimulation current levels may be applied to multiple stimulation sites simultaneously by way of multiple electrodes <NUM>.

<FIG> illustrates a schematic structure of the human cochlea <NUM> into which electrode lead <NUM> may be inserted. As shown in <FIG>, cochlea <NUM> is in the shape of a spiral beginning at a base <NUM> and ending at an apex <NUM>. Within cochlea <NUM> resides auditory nerve tissue <NUM>, which is denoted by Xs in <FIG>. The auditory nerve tissue <NUM> is organized within the cochlea <NUM> in a tonotopic manner. Relatively low frequencies are encoded at or near the apex <NUM> of the cochlea <NUM> (referred to as an "apical region") while relatively high frequencies are encoded at or near the base <NUM> (referred to as a "basal region"). Hence, electrical stimulation applied by way of electrodes disposed within the apical region (i.e., "apical electrodes") may result in the recipient perceiving relatively low frequencies and electrical stimulation applied by way of electrodes disposed within the basal region (i.e., "basal electrodes") may result in the recipient perceiving relatively high frequencies. The delineation between the apical and basal electrodes on a particular electrode lead may vary depending on the insertion depth of the electrode lead, the anatomy of the recipient's cochlea, and/or any other factor as may serve a particular implementation.

<FIG> illustrates an exemplary diagnostic system <NUM> that may be configured to perform any of the operations described herein. As shown, diagnostic system <NUM> may include, without limitation, a storage facility <NUM> and a processing facility <NUM> selectively and communicatively coupled to one another. Facilities <NUM> and <NUM> may each include or be implemented by hardware and/or software components (e.g., processors, memories, communication interfaces, instructions stored in memory for execution by the processors, etc.). In some examples, facilities <NUM> and <NUM> may be distributed between multiple devices and/or multiple locations as may serve a particular implementation.

Storage facility <NUM> may maintain (e.g., store) executable data used by processing facility <NUM> to perform any of the operations described herein. For example, storage facility <NUM> may store instructions <NUM> that may be executed by processing facility <NUM> to perform any of the operations described herein. Instructions <NUM> may be implemented by any suitable application, software, code, and/or other executable data instance. Storage facility <NUM> may also maintain any data received, generated, managed, used, and/or transmitted by processing facility <NUM>.

Processing facility <NUM> may be configured to perform (e.g., execute instructions <NUM> stored in storage facility <NUM> to perform) various operations associated with monitoring evoked responses that occur within a recipient of a cochlear implant during an electrode lead insertion procedure in which an electrode lead is inserted into a cochlea of the recipient. For example, processing facility <NUM> may determine a minimum evoked response amplitude and a maximum evoked response amplitude for a recipient of a cochlear implant and determine a mapping between a plurality of audible pitches and a plurality of evoked response amplitudes included in a range defined by the minimum and maximum evoked response amplitudes. Processing facility <NUM> may also monitor, during an insertion procedure in which an electrode lead communicatively coupled to the cochlear implant is inserted into a cochlea of the recipient, an evoked response signal recorded during the insertion procedure by an electrode disposed on the electrode lead, the evoked response signal representing amplitudes of a plurality of evoked responses that occur within the recipient in response to acoustic stimulation applied to the recipient. Processing facility <NUM> may detect an amplitude change in the evoked response signal as the evoked response signal is being monitored and present, based on the mapping and as the evoked response signal is being monitored, acoustic feedback that audibly indicates the amplitude change. These operations are described in more detail herein.

Diagnostic system <NUM> may be implemented in any suitable manner. For example, diagnostic system <NUM> may be implemented by a stand-alone diagnostic system that may be used in a surgical operating room to perform any of the operations described herein.

<FIG> illustrates an exemplary stand-alone diagnostic system <NUM> that may implement diagnostic system <NUM>. As shown, diagnostic system <NUM> includes a computing module <NUM> and a base module <NUM>. Computing module <NUM> includes a display screen <NUM> and a processor <NUM>. Base module <NUM> includes an interface unit <NUM>, an audio amplifier <NUM>, an audio output port <NUM>, a communications port <NUM>, and a port <NUM>. Computing module <NUM> and base module <NUM> may include additional or alternative components as may serve a particular implementation. For example, computing module <NUM> and/or base module <NUM> may include one or more speakers configured to output acoustic feedback and/or other types of sound configured to be heard by a surgeon and/or other user of diagnostic system <NUM>. Diagnostic system <NUM> and exemplary implementations thereof are described more fully in co-pending <CIT>, which application is filed the same day as the present application and incorporated herein by reference in its entirety.

In the configuration shown in <FIG>, base module <NUM> is physically attached to computing module <NUM>. In this configuration, processor <NUM> is communicatively coupled to interface unit <NUM> by way of a connection <NUM>. Connection <NUM> may be implemented by any suitable connection (e.g., an internal USB connection) as may serve a particular implementation. As will be described in more detail below, base module <NUM> may be selectively detached from computing module <NUM> and connected to a different computing device by way of port <NUM>.

Display screen <NUM> may be configured to display any suitable content associated with an application executed by processor <NUM>. Display screen <NUM> may be implemented by a touchscreen and/or any other type of display screen as may serve a particular implementation.

Processor <NUM> may be configured to execute a diagnostic application associated with a cochlear implant (e.g., cochlear implant <NUM>). For example, processor <NUM> may execute a diagnostic application that may be used during a surgical procedure associated with the cochlear implant. The diagnostic application may be configured to perform various diagnostic operations associated with the cochlear implant during the surgical procedure. Exemplary diagnostic operations are described herein.

In some examples, processor <NUM> may direct display screen <NUM> to display a graphical user interface associated with the diagnostic application being executed by processor <NUM>. A user may interact with the graphical user interface to adjust one or more parameters associated with the cochlear implant and/or otherwise obtain information that may be useful during a procedure associated with the cochlear implant.

Base module <NUM> may be configured to attach to computing module <NUM> and serve as a stand for computing module <NUM>.

Interface unit <NUM> is configured to be communicatively coupled to processor <NUM> by way of connection <NUM> while base module <NUM> is attached to computing module <NUM>. Interface unit <NUM> is further configured to be communicatively coupled to the cochlear implant while base module <NUM> is attached to computing module <NUM>. In this manner, interface unit <NUM> provides an interface between processor <NUM> and the cochlear implant.

Interface unit <NUM> may be communicatively coupled to the cochlear implant by way of communications port <NUM>. For example, communications port <NUM> may be selectively coupled to a coil (e.g., a coil included in a headpiece, such as headpiece <NUM>, or a disposable stand-alone coil) configured to wirelessly communicate with the cochlear implant. Interface unit <NUM> may communicate with the cochlear implant by transmitting and/or receiving data to/from the cochlear implant by way of the coil connected to communications port <NUM>.

Interface unit <NUM> may be further configured to generate and provide acoustic stimulation (e.g., sound waves) to the recipient of the cochlear implant. To this end, audio output port <NUM> is configured to be selectively coupled to a sound delivery apparatus. In some examples, the sound delivery apparatus may be implemented by tubing that has a distal portion configured to be placed in or near an entrance to an ear canal of a recipient of the cochlear implant. While the sound delivery apparatus is connected to audio output port <NUM>, interface unit <NUM> may transmit the acoustic stimulation to the recipient by way of the sound delivery apparatus.

As shown, audio amplifier <NUM> may be positioned within a path between interface unit <NUM> and audio output port <NUM>. In this configuration, audio amplifier <NUM> may be configured to amplify the acoustic stimulation before the acoustic stimulation is delivered to the recipient by way of audio output port <NUM> and the sound delivery apparatus. In some alternative examples, amplification of the acoustic stimulation generated by interface unit <NUM> is not necessary, thereby obviating the need for audio amplifier <NUM> to be included in base module <NUM>. Hence, in some implementations, base module <NUM> does not include audio amplifier <NUM>.

In some examples, diagnostic system <NUM> may be configured to self-calibrate and/or perform in-situ testing. For example, processor <NUM> may calibrate an amplitude level of acoustic stimulation generated by interface unit <NUM> before and/or during a surgical procedure. Such self-calibration and in-situ testing may be performed in any suitable manner.

As mentioned, base module <NUM> may be selectively detached from computing module <NUM>. To illustrate, <FIG> shows a configuration <NUM> in which base module <NUM> is detached from computing module <NUM>. This detachment is illustrated by arrow <NUM>. While detached, interface unit <NUM> of base module <NUM> may be communicatively coupled to a computing device <NUM>. For example, interface unit <NUM> may be communicatively coupled to computing device <NUM> by plugging a cable (e.g., a USB cable) into port <NUM> and into computing device <NUM>. In this configuration, computing device <NUM> may use interface unit <NUM> to interface with a cochlear implant (e.g., by providing acoustic stimulation to a recipient of the cochlear implant and/or receiving recording data from the cochlear implant).

<FIG> depicts an exemplary configuration <NUM> in which diagnostic system <NUM> is used to perform one or more diagnostic operations during a surgical procedure involving a cochlear implant and an electrode lead. The surgical procedure may include, for example, an insertion procedure in which the cochlear implant is inserted into an incision pocket formed within the recipient and/or in which a distal portion of the electrode lead is positioned within the cochlea.

Various anatomical features of the recipient's ear are shown in <FIG>. Specifically, anatomical features include a pinna <NUM> (i.e., the outer ear), an ear canal <NUM>, a middle ear <NUM>, and a cochlea <NUM>. While no specific incision or other explicit surgical representation is shown in <FIG>, it will be understood that such elements may be present when a surgical procedure is ongoing. For example, an incision may be present to allow the surgeon internal access to the recipient to insert the lead into cochlea <NUM>. In some procedures, pinna <NUM> may be taped down and covered with surgical drapes so as to cover ear canal <NUM> (e.g., to help prevent fluids from reaching ear canal <NUM>).

In the example of <FIG>, a cochlear implant <NUM> and an electrode lead <NUM> are shown to be implanted within the recipient. Cochlear implant <NUM> may be similar, for example, to cochlear implant <NUM>, and electrode lead <NUM> may be similar, for example, to electrode lead <NUM>. Electrode lead <NUM> includes a plurality of electrodes (e.g., electrode <NUM>, which is the distal-most electrode disposed on electrode lead <NUM>).

As shown, a cable <NUM> of a headpiece <NUM> is connected to communications port <NUM>. In this configuration, interface unit <NUM> may wirelessly communicate with cochlear implant <NUM> by way of a coil and/or other electronics included in headpiece <NUM>, which may be similar to headpiece <NUM>.

As also shown, a sound delivery apparatus <NUM> is connected to audio output port <NUM>. Sound delivery apparatus <NUM> includes tubing <NUM> and an ear insert <NUM>. Ear insert <NUM> is configured to fit at or within an entrance of ear canal <NUM>. Tubing <NUM> and ear insert <NUM> together form a sound propagation channel <NUM> that delivers acoustic stimulation provided by interface unit <NUM> to the ear canal <NUM>. Tubing <NUM> and ear insert <NUM> may be made out of any suitable material as may serve a particular implementation.

In some examples, processor <NUM> may execute a diagnostic application during the surgical procedure. In accordance with the diagnostic application, processor <NUM> may transmit, by way of connection <NUM>, a command (also referred to as a stimulation command) to interface unit <NUM> for interface unit <NUM> to apply acoustic stimulation to the recipient and receive recording data representative of an evoked response that occurs within the recipient in response to the acoustic stimulation. In response to receiving the command, interface unit <NUM> may generate and apply the acoustic stimulation to the recipient by way of audio output port <NUM> and sound delivery apparatus <NUM>. Interface unit <NUM> may also transmit a command (also referred to as a recording command) to cochlear implant <NUM> by way of communications port <NUM> and headpiece <NUM> for cochlear implant <NUM> to use electrode <NUM> to record the evoked response that occurs in response to the acoustic stimulation. Cochlear implant <NUM> may transmit the recording data back to interface unit <NUM> by way of headpiece <NUM> and communications port <NUM>. Interface unit <NUM> may transmit the recording data to processor <NUM> by way of connection <NUM>. Processor <NUM> may process the recording data and direct display screen <NUM> to display one or more graphical user interfaces associated with the recording data.

In configuration <NUM>, headpiece <NUM> is connected directly to communications port <NUM> by way of cable <NUM>. Hence, in configuration <NUM>, interface unit <NUM> is configured to directly control cochlear implant <NUM>. <FIG> illustrates an alternative configuration <NUM> in which a sound processor <NUM> is included in the communication path in between interface unit <NUM> and cochlear implant <NUM>. Sound processor <NUM> may be similar to any of the sound processors (e.g., sound processor <NUM>) described herein. In some examples, sound processor <NUM> is recipient-agnostic. In other words, sound processor <NUM> is not configured specifically for the recipient of cochlear implant <NUM>. Rather, sound processor <NUM> may be used in a variety of different surgical procedures associated with a number of different recipients.

As shown, sound processor <NUM> is connected to communications port <NUM> by way of a cable <NUM>. Sound processor <NUM> is also connected to headpiece <NUM> by way of cable <NUM>. In this configuration, sound processor <NUM> may relay data and/or commands between interface unit <NUM> and cochlear implant <NUM>.

<FIG> illustrates an alternative configuration <NUM> in which sound processor <NUM> is configured to generate the acoustic stimulation that is applied to the recipient of cochlear implant <NUM>. As shown, in this configuration, a sound delivery apparatus <NUM> is coupled directly to sound processor <NUM>. For example, sound processor <NUM> may be implemented by a behind-the-ear bimodal sound processor and sound delivery apparatus <NUM> may be implemented by an audio ear hook that connects to sound processor <NUM>.

It will be recognized that diagnostic system <NUM> may be additionally or alternatively implemented in any other suitable manner. For example, diagnostic system <NUM> may be implemented by a fitting system utilized in a clinician's office and/or by any other appropriately configured system or device.

An exemplary hardware implementation of diagnostic system <NUM> will now be described in connection with <FIG>. In particular, <FIG> shows a left perspective view of diagnostic system <NUM>, <FIG> shows a right perspective view of diagnostic system <NUM>, <FIG> shows a front view of diagnostic system <NUM>, <FIG> shows a back view of diagnostic system <NUM>, <FIG> shows a left side view of diagnostic system <NUM>, <FIG> shows a right side view of diagnostic system <NUM>, and <FIG> shows a rear perspective view of diagnostic system <NUM>.

The hardware implementation of diagnostic system <NUM> illustrated in <FIG> includes computing module <NUM> and base module <NUM>. As, illustrated computing module <NUM> includes a front side <NUM>, a back side <NUM>, a left side <NUM>, a right side <NUM>, a top side <NUM>, and a bottom side <NUM>.

Display screen <NUM> is located on front side <NUM> of computing module <NUM>. Various other components are also located on the front side <NUM> of computing module <NUM>. For example, a fingerprint scanner <NUM>, physical input buttons <NUM>, and a webcam <NUM> all shown to be included on the front side <NUM> of computing module <NUM>. It will be recognized that any of these components may be located on any other side of computing module <NUM> as may serve a particular implementation.

Fingerprint scanner <NUM> is configured to facilitate authentication of a user of diagnostic system <NUM>. For example, fingerprint scanner <NUM> may detect a fingerprint of the user and provide processor <NUM> with data representative of the fingerprint. Processor <NUM> may process the fingerprint data in any suitable manner (e.g., by comparing the fingerprint to known fingerprints included in a database) to authenticate the user.

Webcam <NUM> may be configured to facilitate video communication by a user of diagnostic system <NUM> with a remotely located user (e.g., during a surgical procedure). Such video communication may be performed in any suitable manner.

Physical input buttons <NUM> may be implemented, for example, by a directional pad and/or any other suitable type of physical input button. A user of diagnostic system <NUM> may interact with physical input buttons <NUM> to perform various operations with respect to a diagnostic application being executed by processor <NUM>. For example, the user may use the physical input buttons <NUM> to interact with a graphical user interface displayed on display screen <NUM>.

In some examples, physical input buttons <NUM> may be configured to be selectively programmed (e.g., as hotkeys) to perform one or more functions associated with the diagnostic application. For example, a particular physical input button <NUM> may be programmed by a user to start and/or stop acoustic stimulation being applied to a cochlear implant recipient by diagnostic system <NUM>.

In some examples, processor <NUM> may be configured to wirelessly connect to an input device configured to be used by the user in connection with the diagnostic application. For example, processor <NUM> may be configured to wirelessly connect (e.g., via Bluetooth and/or any other suitable wireless communication protocol) to a keyboard, mouse, remote control, and/or any other wireless input device as may serve a particular implementation. In this manner, the user may selectively use physical input buttons <NUM>, a touchscreen capability of display screen <NUM>, and/or a wireless input device to interact with diagnostic system <NUM>.

As shown, a hole <NUM> may be formed within computing module <NUM> and configured to serve as a handle for diagnostic system <NUM>. A user may grip computing module <NUM> by placing his or her fingers within hole <NUM>.

As shown, a barcode scanner <NUM> may be located on left side <NUM> of computing module <NUM>. Barcode scanner <NUM> may alternatively be located on any other side of computing module <NUM>. In some examples, barcode scanner <NUM> may be configured to scan for an activation code included on one or more components associated with a procedure being performed with respect to cochlear implant <NUM>. The activation code may be used to associate (e.g., register) the components with cochlear implant <NUM>.

As illustrated in <FIG>, computing module <NUM> may include batteries <NUM>-<NUM> and <NUM>-<NUM>. Batteries <NUM> may be configured to provide operating power for various components included within computing module <NUM> and base module <NUM>. In some examples, batteries <NUM> may be hot-swappable. In other words, one of batteries <NUM> (e.g., battery <NUM>-<NUM>) may be removed and replaced while the other battery (e.g., battery <NUM>-<NUM>) is used to provide power to computing module <NUM> and base module <NUM>.

As illustrated in <FIG> and <FIG>, ports <NUM>, <NUM>, and <NUM> are located on a side surface <NUM> of base module <NUM>. Ports <NUM>, <NUM>, and <NUM> may alternatively be located on any other surface of base module <NUM>.

As described above, base module <NUM> may be configured to serve as a stand for computing module <NUM> while base module <NUM> is attached to computing module <NUM>. The stand functionality of base module <NUM> is illustrated in <FIG>.

As shown, base module <NUM> includes a top surface <NUM> configured to selectively attach to back side <NUM> of computing module <NUM>. Base module <NUM> may alternatively attach to any other side of computing module <NUM>. Base module <NUM> further includes a bottom surface <NUM> configured to be placed on a resting surface <NUM>. Bottom surface <NUM> is angled with respect to back side <NUM> of computing module <NUM>. This provides a viewing angle <NUM> for display screen <NUM> that is greater than zero degrees with respect to resting surface <NUM>. In some examples, base module <NUM> may be adjustable to selectively provide different viewing angles for display screen <NUM> with respect to resting surface <NUM>. This adjustability may be realized in any suitable manner. For example, a user may manually adjust bottom surface <NUM> to different angles with respect to back side <NUM> of computing module <NUM>.

<FIG> illustrates an exemplary configuration in which base module <NUM> is detached from computing module <NUM>. Base module <NUM> may be detached from computing module <NUM> in any suitable manner. For example, base module <NUM> may include one or more locking mechanisms that may be actuated by a user to detach base module <NUM> from computing module <NUM>.

Various operations that may be performed by diagnostic system <NUM> will now be described. It will be recognized that diagnostic system <NUM> may perform additional or alternative operations to those described herein as may serve a particular implementation.

In some examples, diagnostic system <NUM> may determine a minimum evoked response amplitude and a maximum evoked response amplitude for a recipient of a cochlear implant. The minimum and maximum evoked response amplitudes define a range of evoked response amplitudes that are expected to occur within the recipient in response to acoustic stimulation applied to the recipient. Diagnostic system <NUM> may determine the minimum and maximum evoked response amplitudes in any suitable manner.

For example, as will be described in more detail below, diagnostic system <NUM> may present a graphical user interface by way of a display screen (e.g., display screen <NUM> or any other suitable display screen) and detect user input provided by way of the graphical user interface that is representative of the minimum and maximum evoked response amplitudes.

Additionally or alternatively, diagnostic system <NUM> may automatically determine the minimum and maximum evoked response amplitudes based on various characteristics of the acoustic stimulation that is to be applied to elicit the evoked responses, the recipient, and/or the electrode used to record the evoked responses. For example, the diagnostic system may automatically determine the minimum and maximum evoked response amplitudes based on a stimulation level (e.g., amplitude) of the acoustic stimulation that is to be applied to elicit the evoked responses, an age of the recipient, a pre-operative hearing assessment for the recipient, an impedance of the electrode, and/or any other suitable factor as may serve a particular implementation.

Once the minimum and maximum evoked response amplitudes have been determined, diagnostic system <NUM> may determine a mapping between a plurality of audible pitches and a plurality of evoked response amplitudes included in a range defined by the minimum and maximum evoked response amplitudes. For example, the plurality of audible pitches may include only a predetermined number of audible pitches (e.g., ten or fifteen different audible pitches). The lowest audible pitch within plurality of audible pitches may be mapped to the minimum evoked response amplitude. Likewise, the highest audible pitch within the plurality of audible pitches may be mapped to the maximum evoked response amplitude. A remaining number of available pitches within the plurality of audible pitches may be mapped to different evoked response amplitudes that are in between the minimum and maximum evoked response amplitudes.

To illustrate, <FIG> illustrate two different mappings <NUM>-<NUM> and <NUM>-<NUM> that may be performed by diagnostic system <NUM>. In mapping <NUM>-<NUM>, a total of ten audible pitches <NUM>-<NUM> through <NUM>-<NUM> (collectively "audible pitches <NUM>") are mapped to a first range of evoked response amplitudes represented by line <NUM>-<NUM> and defined by a minimum evoked response amplitude A1 and a maximum evoked response amplitude A10. In mapping <NUM>-<NUM>, the same audible pitches <NUM> are mapped to a second range of evoked response amplitudes represented by line <NUM>-<NUM> and defined by a minimum evoked response amplitude B1 and a maximum evoked response amplitude B10. As illustrated by the relative lengths of lines <NUM>-<NUM> and <NUM>-<NUM>, the first range of evoked response amplitudes is greater than the second range of evoked response amplitudes.

In <FIG>, the lowest audible pitch <NUM>-<NUM> included in the plurality of audible pitches <NUM> is mapped to the minimum evoked response amplitude A1 and the highest audible pitch <NUM>-<NUM> included in the plurality of audible pitches <NUM> is mapped to the maximum evoked response amplitude A10. The remaining audible pitches <NUM>-<NUM> through <NUM>-<NUM> are mapped to evoked response amplitudes A2 through A9, which are each included in the range defined by minimum evoked response amplitude A1 and maximum evoked response amplitude A10. In some examples, the mappings of audible pitches <NUM>-<NUM> through <NUM>-<NUM> are evenly distributed between the minimum and maximum evoked response amplitudes A1 and A10. The mapping of audible pitches <NUM>-<NUM> through <NUM>-<NUM> may alternatively be distributed in any suitable manner.

In <FIG>, the lowest audible pitch <NUM>-<NUM> included in the plurality of audible pitches <NUM> is mapped to the minimum evoked response amplitude B1 and the highest audible pitch <NUM>-<NUM> included in the plurality of audible pitches <NUM> is mapped to the maximum evoked response amplitude B10. The remaining audible pitches <NUM>-<NUM> through <NUM>-<NUM> are mapped to evoked response amplitudes B2 through B9, which are each included in the range defined by minimum evoked response amplitude B1 and maximum evoked response amplitude B10. In some examples, the mappings of audible pitches <NUM>-<NUM> through <NUM>-<NUM> are evenly distributed between the minimum and maximum evoked response amplitudes B1 and B10. The mapping of audible pitches <NUM>-<NUM> through <NUM>-<NUM> may alternatively be distributed in any suitable manner.

By using the same audible pitches <NUM> in mappings <NUM>-<NUM> and <NUM>-<NUM>, as well as all other mappings performed by diagnostic system <NUM>, diagnostic system <NUM> may provide the same acoustic feedback experience to a user regardless of what the minimum and maximum evoked response amplitudes are set to be. This may allow a user to become accustomed to what the user should hear in terms of acoustic feedback as an electrode lead is inserted into the cochlea.

In some examples, audible pitches <NUM> may be musically related one to another. For example, audible pitches <NUM>-<NUM> through <NUM>-<NUM> may each correspond to a musical note included in a musical scale. In this manner, the acoustic feedback may be pleasant to hear and allow the user to readily ascertain what audible pitch should be played at a particular point during an electrode lead insertion procedure.

During an insertion procedure in which an electrode lead communicatively coupled to a cochlear implant is inserted into a cochlea of a recipient, diagnostic system <NUM> may monitor an evoked response signal recorded during the insertion procedure by an electrode on the insertion lead. To this end, diagnostic system <NUM> may direct an acoustic stimulation generator to apply acoustic stimulation to the recipient during the insertion procedure. Diagnostic system <NUM> may also direct the cochlear implant to use an electrode disposed on the electrode lead to record the evoked response signal.

The acoustic stimulation generator may be implemented by interface unit <NUM>, a behind-the-ear bimodal sound processor comprising an earhook (e.g., sound processor <NUM> shown in <FIG>), and/or any other component configured to generate acoustic stimulation. For example, in configuration <NUM> shown in <FIG> and configuration <NUM> shown in <FIG>, processor <NUM> implementing diagnostic system <NUM> may direct interface unit <NUM> to generate and apply acoustic stimulation to the recipient of cochlear implant <NUM> by way of sound delivery apparatus <NUM>. As another example, in configuration <NUM> shown in <FIG>, processor <NUM> implementing diagnostic system <NUM> may direct sound processor <NUM> to generate and apply acoustic stimulation to the recipient of cochlear implant <NUM> by way of sound delivery apparatus <NUM>. In all of these configurations, processor <NUM> may direct cochlear implant <NUM> to use electrode <NUM> to record the evoked response signal. Use of electrode <NUM> to record the evoked response signal is beneficial in many configurations because electrode <NUM> is the first to enter the cochlea. However, it will be recognized that any other electrode disposed on electrode lead <NUM> may be used to record the evoked response signal.

Diagnostic system <NUM> may monitor the evoked response signal in any suitable manner. For example, diagnostic system <NUM> may monitor the evoked response signal by receiving data representative of the evoked response signal from the cochlear implant, analyzing the evoked response signal in real time during the insertion procedure, and performing various actions associated with the evoked response signal. For example, as will be described herein, diagnostic system <NUM> may plot the evoked response signal within a graphical user interface, provide acoustic feedback in real time as the evoked response signal is recorded, detect one or more events that occur within the evoked response signal, provide notifications of the one or more events, etc..

While diagnostic system <NUM> monitors the evoked response signal, diagnostic system <NUM> may detect an amplitude change in the evoked response signal and present acoustic feedback (e.g., by way of one or more speakers) that audibly indicates the amplitude change. To illustrate, the acoustic feedback may be based on mapping <NUM>-<NUM>. In this example, the evoked response amplitude may initially be A2. As such, diagnostic system <NUM> may initially present a tone that has audible pitch <NUM>-<NUM>. In response to a change in evoked response amplitude from A2 to A3, diagnostic system may present a tone that has audible pitch <NUM>-<NUM>. This change in audible pitch audibly indicates to a user that the evoked response amplitude has changed from A2 to A3.

In some examples, diagnostic system <NUM> may direct the display screen to display a graph of the evoked response signal as the evoked response signal is being recorded. In this manner, diagnostic system <NUM> may also graphically indicate amplitude changes that occur in the evoked response signal. Diagnostic system <NUM> may synchronize the presentation of the acoustic feedback and the display of the graph such that the acoustic feedback and the graph indicate the amplitude changes at substantially the same time. In this manner, a user may selectively rely on the acoustic feedback and/or the graph to monitor the evoked response signal.

<FIG> illustrates an exemplary graphical user interface <NUM> that may be presented by diagnostic system <NUM> by way of a display screen. As shown, graphical user interface <NUM> includes a graph <NUM> of an evoked response signal <NUM> that may be recorded by an electrode during an electrode lead insertion procedure. As shown, graph <NUM> plots the amplitude (y-axis) of the evoked response signal <NUM> with respect to time (x-axis). While <FIG> shows evoked response signal <NUM> plotted after <NUM> seconds, it will be recognized that the evoked response signal <NUM> may be plotted in real time as the electrode insertion procedure occurs.

As shown, evoked response signal <NUM> is initially flat prior to callout A (which is around <NUM> seconds in to the electrode lead insertion procedure). This may indicate that the electrode being used to record the evoked response signal <NUM> has not yet reached the round window. However, between callout A and callout B (which is around <NUM> seconds in to the electrode lead insertion procedure), the evoked response signal <NUM> increases in amplitude at a constant rate. This graphically indicates that the electrode lead is being properly inserted into the cochlea. As the evoked response signal <NUM> increases in amplitude, diagnostic system <NUM> may present acoustic feedback that correspondingly increases in audible pitch, as described herein.

At callout B, there is a sudden drop in amplitude of evoked response signal <NUM>. In particular, the amplitude of evoked response signal <NUM> drops from about <NUM>µV to about <NUM>µV. This sudden drop in evoked response amplitude may be indicative of an event that occurs during the electrode lead insertion procedure. For example, the sudden drop in evoked response amplitude may indicate that the electrode lead has penetrated or is otherwise damaging a wall of the cochlea. They event associated with the sudden drop may additionally or alternatively include any other type of event as may serve a particular implementation.

In response to the sudden drop in amplitude of evoked response signal <NUM>, diagnostic system <NUM> may correspondingly decrease the audible pitch of the acoustic feedback being presented to indicate the drop in amplitude. Additionally or alternatively, diagnostic system <NUM> may present a different type of acoustic feedback (referred to herein as event-based acoustic feedback) that specifically indicates the occurrence of an event.

For example, diagnostic system <NUM> may maintain data representative of an event threshold. The event threshold may be any suitable amount (e.g., in dB or µV) to which an evoked response amplitude change over a predetermined amount of time (e.g., a relatively short amount of time) may be compared in order to determine whether an event has occurred. For example, the event threshold may be <NUM> dB. In this example, if diagnostic system <NUM> determines that the amplitude of evoked response signal <NUM> changes by at least <NUM> dB within a predetermined amount time, diagnostic system <NUM> may determine that an event has occurred and provide event-based acoustic feedback that is distinct from the acoustic feedback being used to generally indicate changes in the amplitude of evoked response signal <NUM>.

In some examples, the event-based acoustic feedback does not include any of the audible pitches included in the acoustic feedback used to generally indicate changes in the amplitude of evoked response signal <NUM>. For example, the event-based acoustic feedback may include one or more beeps over other alarm-like sounds. In some examples, the event-based acoustic feedback is presented concurrently with the acoustic feedback used to generally indicate changes in the amplitude of evoked response signal <NUM>.

While <FIG> illustrates a sudden drop in amplitude of evoked response signal <NUM>, it will be recognized that other types of events may be associated with sudden increases in amplitude of evoked response signal <NUM>. Acoustic feedback representative of the sudden increases in amplitude may be presented to the user in a similar manner.

In some examples, a sudden change in phase of an evoked response signal recorded by the electrode may additionally or alternatively be used to determine that an event, such as damage to the cochlea, has occurred. This is described in more detail in <CIT>, which application is incorporated herein by reference in its entirety. Hence, in some examples, diagnostic system <NUM> may track the phase of the evoked response signal and provide acoustic feedback if the phase changes more than a threshold amount (e.g., more than <NUM> radians) over a predetermined time period. In some alternative examples, the acoustic feedback may be provided if the amplitude changes more than a threshold amount without the phase changing.

As shown in <FIG>, graphical user interface <NUM> may include a start option <NUM> and a stop option <NUM> displayed therein. A user may interact with these options to direct diagnostic system <NUM> to begin and stop monitoring evoked response signal <NUM>. For example, graphical user interface <NUM> may detect a selection of start option <NUM>. In response, diagnostic system <NUM> may begin monitoring evoked response signal <NUM>. While monitoring evoked response signal <NUM>, diagnostic system <NUM> may detect a user selection of stop option <NUM>. In response, diagnostic system <NUM> may stop monitoring evoked response signal <NUM>.

In some examples, in response to detecting a user selection of start option <NUM> (or any other command that directs diagnostic system <NUM> to begin monitoring evoked response signal <NUM>), diagnostic system <NUM> may measure an impedance of the electrode being used to record evoked response signal <NUM> and abstain from beginning to monitor evoked response signal <NUM> until the impedance of the electrode is below a predetermined threshold. This below threshold impedance of the electrode may indicate that the electrode is touching the round window within the ear of the recipient. At this point, diagnostic system <NUM> may begin applying acoustic stimulation to the recipient and monitoring evoked response signal <NUM> that occurs in response to the acoustic stimulation.

To illustrate, in the example of <FIG>, start option <NUM> was selected by the user at time equals zero seconds. In response, diagnostic system <NUM> began measuring the impedance of the electrode used to record evoked response signal <NUM>. At the time associated with callout A, diagnostic system <NUM> determined that the impedance of the electrode went below the predetermined threshold. Between time zero and the time associated with callout A, diagnostic system <NUM> abstained from monitoring evoked response signal <NUM> (e.g., by abstaining from presenting acoustic stimulation to the recipient during this time period). At the time associated with callout A, diagnostic system <NUM> began applying the acoustic stimulation to the recipient and monitoring the resultant evoked response signal <NUM>.

In some examples, diagnostic system <NUM> may be configured to use multi-rate analysis to detect amplitude changes in evoked response signal <NUM> and present acoustic feedback indicating the amplitude changes. For example, diagnostic system <NUM> may employ a plurality of averagers in parallel that each average a different number of samples (e.g., one, two, four, eight, sixteen, and thirty-two samples) of evoked response signal <NUM>. If any averager detects a change in evoked response signal <NUM>, diagnostic system <NUM> may plot the change within graph <NUM>. The averagers are then all reset to be maximally sensitive to the next change. Diagnostic system <NUM> may be configured to ignore data where there is motion or other artifact from the change analysis. By using multi-rate analysis, diagnostic system <NUM> may detect changes in amplitude of evoked response signal <NUM> at an optimal rate.

<FIG> illustrates an exemplary graphical user interface <NUM> that may be presented by diagnostic system <NUM> and that may facilitate user control of various settings associated with monitoring evoked responses that occur during an electrode lead insertion procedure.

For example, a user may interact with a slider <NUM> to selectively enable or disable acoustic feedback during the electrode lead insertion procedure. In the example of <FIG>, the position of slider <NUM> indicates that acoustic feedback is to be provided during the electrode lead insertion procedure.

The user may additionally or alternatively interact with field <NUM> to provide user input representative of an event threshold. In the example of <FIG>, the event threshold is set to <NUM> dB, which, as described above, means that if a change in evoked response amplitude is greater than <NUM> dB (e.g., between subsequent evoked response amplitude samplings or during a particular time period), diagnostic system <NUM> may determine that an event has occurred and provide acoustic feedback representative of the event.

The user may additionally or alternatively interact with fields <NUM> and <NUM> to provide user input that sets the minimum evoked response amplitude and the maximum evoked response amplitude. As shown, the minimum evoked response amplitude is set to <NUM> microvolts (µV) and the maximum evoked response amplitude is set to <NUM>µV. As described above, the minimum and maximum evoked response amplitudes define a range of evoked response amplitudes that are expected to occur within the recipient.

The user may additionally or alternatively interact with fields <NUM> and <NUM> to provide user input that specifies a frequency and stimulation level, respectively, of the acoustic stimulation that is applied to the recipient to elicit evoked responses. In the example of <FIG>, the acoustic stimulation frequency is set to <NUM> and the acoustic stimulation level is set to <NUM> dB HL.

In some examples, diagnostic system <NUM> may be configured to perform any of the operations described herein while operating in a "demo" mode. In the demo mode, instead of performing operations with respect to an actual recipient of a cochlear implant, diagnostic system <NUM> may perform the operations with respect to one or more recipient models. In this manner, diagnostic system <NUM> may readily provide opportunities for user training.

<FIG> illustrates an exemplary method <NUM>. The operations shown in <FIG> may be performed by diagnostic system <NUM> and/or any implementation thereof. While <FIG> illustrates exemplary operations according to one embodiment, other embodiments may omit, add to, reorder, and/or modify any of the operations shown in <FIG>.

In operation <NUM>, a diagnostic system determines a minimum evoked response amplitude and a maximum evoked response amplitude for a recipient of a cochlear implant. Operation <NUM> may be performed in any of the ways described herein.

In operation <NUM>, the diagnostic system determines a mapping between a plurality of audible pitches and a plurality of evoked response amplitudes included in a range defined by the minimum and maximum evoked response amplitudes. Operation <NUM> may be performed in any of the ways described herein.

In operation <NUM>, the diagnostic system monitors, during an insertion procedure in which an electrode lead communicatively coupled to the cochlear implant is inserted into a cochlea of the recipient, an evoked response signal recorded during the insertion procedure by an electrode disposed on the electrode lead, the evoked response signal representing amplitudes of a plurality of evoked responses that occur within the recipient in response to acoustic stimulation applied to the recipient. Operation <NUM> may be performed in any of the ways described herein.

In operation <NUM>, the diagnostic system detects an amplitude change in the evoked response signal as the evoked response signal is being monitored. Operation <NUM> may be performed in any of the ways described herein.

In operation <NUM>, the diagnostic system presents, based on the mapping and as the evoked response signal is being monitored, acoustic feedback that audibly indicates the amplitude change. Operation <NUM> may be performed in any of the ways described herein.

<FIG> illustrates an exemplary computing device <NUM> that may be specifically configured to perform one or more of the processes described herein. As shown in <FIG>, computing device <NUM> may include a communication interface <NUM>, a processor <NUM>, a storage device <NUM>, and an input/output ("I/O") module <NUM> communicatively connected one to another via a communication infrastructure <NUM>. While an exemplary computing device <NUM> is shown in <FIG>, the components illustrated in <FIG> are not intended to be limiting. Additional or alternative components may be used in other embodiments. Components of computing device <NUM> shown in <FIG> will now be described in additional detail.

In some examples, any of the systems, computing devices, and/or other components described herein may be implemented by computing device <NUM>. For example, storage facility <NUM> may be implemented by storage device <NUM>, and processing facility <NUM> may be implemented by processor <NUM>.

Claim 1:
A system comprising:
a memory (<NUM>, <NUM>) storing instructions (<NUM>, <NUM>);
a processor (<NUM>, <NUM>, <NUM>) communicatively coupled to the memory and configured to execute the instructions to:
determine a minimum evoked response amplitude and a maximum evoked response amplitude for a recipient of a cochlear implant (<NUM>, <NUM>);
determine a mapping (<NUM>) between a plurality of audible pitches (<NUM>) and a plurality of evoked response amplitudes (<NUM>) included in a range defined by the minimum and maximum evoked response amplitudes;
monitor, during an insertion procedure in which an electrode lead (<NUM>, <NUM>) communicatively coupled to the cochlear implant is inserted into a cochlea (<NUM>) of the recipient, an evoked response signal (<NUM>) recorded during the insertion procedure by an electrode (<NUM>, <NUM>) disposed on the electrode lead, the evoked response signal representing amplitudes of a plurality of evoked responses that occur within the recipient in response to acoustic stimulation applied to the recipient;
detect an amplitude change in the evoked response signal as the evoked response signal is being monitored; and
present, based on the mapping and as the evoked response signal is being monitored, acoustic feedback that audibly indicates the amplitude change,
wherein the determining of the mapping comprises:
mapping a lowest audible pitch within the plurality of audible pitches to the minimum evoked response amplitude;
mapping a highest audible pitch within the plurality of audible pitches to the maximum evoked response amplitude; and
mapping a remaining number of available pitches within the plurality of audible pitches to different evoked response amplitudes that are in between the minimum and maximum evoked response amplitudes.