Abstract: The accuracy of neural response recordings in neural stimulators, e.g., cochlear implants, is often degraded by a recording artifact. An idealized electrical-equivalent model of a neural stimulator is created to study, measure and compensate for artifact evoked compound action potential (eCAP). Using this model, the artifact is shown to occur even when the electrical components that make-up the neural stimulator are ideal. The model contains parasitic capacitances between the electrode wires. The model demonstrates that these small parasitic capacitances provide a current path during stimulation which can deposit charge on the electrode-tissue interfaces of the recording electrodes. The dissipation of this residual charge and the charge stored across the stimulating electrode is seen as the recording artifact. The proposed solution for eliminating the artifact problem is realized by utilizing a capacitive electrode material, e.g.

Abstract: An adaptive place-pitch ranking procedure for use with a cochlear implant or other neural stimulation system provides a systematic method for quantifying the magnitude and direction of errors along the place-pitch continuum. The method may be conducted and completed in a relatively short period of time. In use, the implant user or listener is asked to rank the percepts obtained after a sequential presentation of monopolar stimulation pulses are applied to a selected spatially-defined electrode pair. The spatially-defined electrode pair may be a physical electrode pair or a virtual electrode pair. A virtual electrode pair includes at least one virtual electrode contact. Should the patient's judgment of pitch order be correct for all applied interrogations, then no further testing involving the tested electrode pair (two electrode contacts) is undertaken.

Abstract: An adaptive place-pitch ranking procedure for use with a cochlear implant or other neural stimulation system provides a systematic method for quantifying the magnitude and direction of errors along the place-pitch continuum. The method may be conducted and completed in a relatively short period of time. In use, the implant user or listener is asked to rank the percepts obtained after a sequential presentation of monopolar stimulation pulses are applied to a selected spatially-defined electrode pair. The spatially-defined electrode pair may be a physical electrode pair or a virtual electrode pair. A virtual electrode pair includes at least one virtual electrode contact. Should the patient's judgment of pitch order be correct for all applied interrogations, then no further testing involving the tested electrode pair (two electrode contacts) is undertaken.

Abstract: Systems for detecting an error associated with an implantable device include a back-telemetry transmitter within the implantable device configured to transmit one or more signals to an external device having a receiver configured to receive the one or more signals. The implantable device includes circuitry configured to detect an error associated with the implantable device, generate a fault signal corresponding to the error, and turn on the back-telemetry transmitter to transmit the fault signal to the external device.

Abstract: Methods of automatically identifying whether a neural recording signal includes a neural response signal include fitting an artifact model to a neural recording signal to produce a fitted artifact model signal, determining a strength-of-response metric that describes a distance of the neural recording signal from the fitted artifact model signal, and identifying the neural recording signal as including a neural response signal if the strength-of-response metric is above a pre-determined threshold. Corresponding systems are also described.

Abstract: A hand-held remote unit functions as both a remote status device and a control device for a cochlear implant system. When placed near the headpiece of a cochlear implant system, the remote unit monitors the forward telemetry signals transmitted between an external sound processor, e.g., a behind-the-ear (BTE) sound processor, and an implanted unit, thereby providing the remote unit with the ability to output status information regarding the implant system. The remote unit may also generate a back telemetry signal that when properly received by the sound processor causes a forward telemetry signal to be generated that controls the implant unit.

Abstract: Methods of removing accumulated charge from one or more electrodes include applying a plurality of stimulation events to one or more stimulation sites within a patient via the one or more electrodes and globally shorting each of the electrodes during a plurality of global shorting periods interspersed among the plurality of stimulation events. Systems for removing accumulated charge from one or more electrodes include a stimulator electrically coupled to the one or more electrodes and configured to apply a plurality of stimulation events to one or more stimulation sites within a patient via the one or more electrodes. The stimulator is further configured to globally short each of the electrodes during a plurality of global shorting periods interspersed among the plurality of stimulation events.

Abstract: Errors in pitch (frequency) allocation within a cochlear implant are corrected in order to provide a significant and profound improvement in the quality of sound perceived by the cochlear implant user. In one embodiment, the user is stimulated with a reference signal, e.g., the tone “A” (440 Hz) and then the user is stimulated with a probe signal, separated from the reference signal by an octave, e.g., high “A” (880 Hz). The user adjusts the location where the probe signal is applied, using current steering, until the pitch of the probe signal, as perceived by the user, matches the pitch of the reference signal, as perceived by the user. In this manner, the user maps frequencies to stimulation locations in order to tune his or her implant system to his or her unique cochlea.

Abstract: Psychophysical tests are administered to cochlear implant (CI) users to determine a spectral modulation transfer function (SMTF), smallest detectable spectral contrast as a function of spectral modulation frequency, for each individual CI user. The determined SMTF for individual CI user is compared against a SMTF of a normal hearing person to determine the specific enhancements needed. A profile of spectral enhancement achievable with variation of filter parameters, sigma and maximum that best fits the needed enhancements for the individual CI user is selected. Based on the corresponding sigma and maximum selected, a sound processing strategy is adjusted to provide customized spectral contrast enhancement for the individual CI user. The sound processing strategy implemented includes an outer hair cell model.

Abstract: Systems for fitting an implantable cochlear stimulator to a patient include an interface unit configured to display a graphical representation of an implant fitting line as part of a graphical user interface. The implant fitting line has a slope and a horizontal position and represents a mapping relationship between a plurality of audio frequencies and a plurality of stimulation sites within a cochlea of the patient. The interface unit is further configured to facilitate adjustment of the slope and/or horizontal position of the fitting line.

Abstract: Audio streaming is made available throughout the signal processing path of the speech processor of a cochlear implant or other audio signal processor. Audio streaming comprises the digitally phase locked playback of a real time n-bit digital audio stream, where n may be a large number, e.g., 8, 12, 16, 24 or 32, that emanates (unsolicited) from an operating speech processor. A number of sample points are made available long the processing chain of a digital signal processor (DSP) used within the speech processor of the cochlear implant. Audio streaming may occur at any sample point. The signal at a selected sample point may be selectively monitored in order to allow appropriate diagnostics to be performed. Audio streaming utilizes an auto-referencing mixed-mode phase locked loop. Such phase locked loop processes an asynchronous stream of digital audio samples that arrive at a designated location, e.g., a selected sample point, at a consistent, but unknown, average rate.

Abstract: Systems for facilitating communication between a first and second device include a voltage level translator circuit configured to convert a voltage level of one or more digital signals that are transmitted from the first device to the second device to a voltage level substantially equal to a supply voltage level of the second device. The conversion is based on a first input voltage signal into the translator circuit. The systems further include a diode in series with a capacitor. The diode is configured to generate the first input voltage signal by charging the capacitor to a voltage level that is substantially equal to the voltage level of the one or more digital signals.

Abstract: Exemplary cochlear implant systems include an implantable head module configured to be implanted within a head of a patient. The implantable head module includes a cochlear stimulator configured to be coupled to an electrode lead, the electrode lead including one or more electrodes configured to be in communication with one or more stimulation sites within the patient. The implantable head module also includes a signal receiver configured to receive a telemetry signal representative of an audio signal from a signal transmitter located external to the patient, a sound processor configured to process the telemetry signal and direct the cochlear stimulator to generate and apply electrical stimulation representative of the audio signal to the one or more stimulation sites via the electrode lead, and a power receiver configured to receive power for operating the implantable head module from a power transmitter located external to the patient.

Abstract: An In The Ear (ITE) microphone improves the acoustic response of a Behind The Ear (BTE) Implantable Cochlear Stimulation (ICS) system during telephone use. The microphone includes means for adjusting the position of the microphone to receive sound waves through a port. An acoustic seal provided by holding a telephone earpiece against the ear provides improved coupling of low frequency (up to about 1 KHz) sound waves, sufficient to overcome losses due to the near field acoustic characteristics common to telephones. In an exemplary embodiment, the ITE microphone is connected to a removable ear hook of the BTE ICS system by a short bendable stalk.

Abstract: Methods of applying stimulation to a stimulation site within a patient include applying stimulation current to the stimulation site via at least one stimulating electrode, applying compensating current configured to affect at least one excitation field caused by the stimulation current via one or more additional electrodes, and dynamically adjusting the compensating current as a function of an amplitude of the stimulation current. Systems for applying stimulation to a stimulation site within a patient include an implantable stimulator, at least one stimulating electrode electrically coupled to the implantable stimulator, and one or more additional electrodes electrically coupled to the implantable stimulator.

Abstract: Contrast between various frequency components of sound is enhanced through a lateral suppression strategy to provide increased speech perception in the electrically stimulated cochlea. A received audio signal is divided into a plurality of input signals, wherein each input signal is associated with a frequency band. A plurality of envelope signals are generated by determining the envelope of each of a plurality of the input signals. At least one of the envelope signals is scaled in accordance with a scaling factor to generate at least one scaled envelope signal. An output signal is generated by combining at least one envelope signal with at least one scaled envelope signal, and the cochlea is stimulated based on the generated output signal. The lateral suppression strategy can be applied to one or more frequency bands using scaled amplitude signals associated with one or more neighboring frequency bands.

Abstract: Methods of selecting a number of channels for stimulation within a neural stimulation system include determining an amplitude of a multiplicity of stimulation signals each corresponding to a channel within a multiplicity of channels in the implantable stimulation system, using the amplitudes of the stimulation signals to determine a probability of each of the stimulation signals, and using the probabilities of one or more of the stimulation signals to randomly select a predetermined number of channels from the multiplicity of channels through which one or more of the stimulation signals are applied to a patient during a stimulation frame.

Abstract: A push-pull amplifier efficiency provides a 4:1 (12 dB) course adjustment of power output by using a single digital control input. The amplifier is provided with an input voltage (VDD) having sixteen steps ranging from 1.25 volts to 3.00 volts. Based on the digital control, an integrated circuit switches between a high power mode and a low power mode. In the low power mode, the output voltage is equivalent to the input voltage. In the high power mode, the amplifier provides an output of twice the input voltage (or four times the power).

Abstract: A push-pull amplifier efficiency provides a 4:1 (12 dB) course adjustment of power output by using a single digital control input. The amplifier is provided with an input voltage (VDD) having sixteen steps ranging from 1.25 volts to 3.00 volts. Based on the digital control, an integrated circuit switches between a high power mode and a low power mode. In the low power mode, the output voltage is equivalent to the input voltage. In the high power mode, the amplifier provides an output of twice the input voltage (or four times the power).

Abstract: Systems for fitting an implantable cochlear stimulator to a patient include an interface unit configured to display a graphical representation of an implant fitting line as part of a graphical user interface. The implant fitting line has a slope and a horizontal position and represents a mapping relationship between a plurality of audio frequencies and a plurality of stimulation sites within a cochlea of the patient. The interface unit is further configured to facilitate adjustment of the slope and/or horizontal position of the fitting line.