A cochlear implant system includes an electrode array (1) comprising multiple platinum ring electrodes in a silastic carrier to be implanted in the cochlea of the ear. A receiver-stimulator (3) containing a semiconductor integrated circuit and other components is implanted in the patient adjacent the ear to receive data information and power through tuned coil (5) using an inductive link (6) from a patient-wearable external speech processor (7) including an integrated circuit and various components which is configured or mapped to emit data signals from an EPROM programmed to suit each patient electrical stimulation perceptions through testing of the patient and his implanted stimulator/electrode using a diagnostic and programming unit (12) connected to the processor by an interface unit (10). The system allows use of various speech processing strategies including dominant spectral peak and amplitude and compression of voice pitch so as to include voiced sounds, unvoiced glottal sounds and prosodic information. Biphastic pulses are supplied to various combinations of electrodes by a switch controlled current sink in various modes of operation. In-place testing of the implant is also provided. Various safety features are incorporated to insure that harmful impulses are not imposed on the patient. Transmission of data is by a series of discrete data bursts which represent the chosen electrode(s), the electrode mode configuration, the stimulating current, and amplitude determined by the duration of the amplitude burst.

Cochlear implant system for an auditory prosthesis

A cochlear implant system includes an implant portion and an external portion. The external portion performs at least the function of sensing acoustic signals and converting such sensed signals to electrical signals. The implant portion performs at least the function of generating electrical stimuli, modulated and classified in response to the sensed acoustic signals, and intended for direct electrical stimulation of the auditory nerve in accordance with a selected speech processing strategy. Control data defines the selected speech processing strategy, i.e., the pulsatile stimulation pattern to be used by implantable portion. Such control data is transmitted to and stored within the implantable portion of the system only once, when a particular speech processing strategy is selected, thereby eliminating the need to continually resend such speech-processing-defining data over a bandwidth-limited link between the implantable and external portions of the system. The control data that defines the selected speech processing strategy is stored in a stimulation template (also referred to as a “pulse table”), which template or table is stored digitally within the implanted portion of the system. Weighting coefficients (or weighting factors) are stored in the template or table at specified locations to define the speech processing strategy. For example, the columns of the template or table may be used to represent the different current sources, or “stimulous channels”, of the implanted portion, and the rows may be used to represent intervals of time. The “stimulous channels” and increments of time thus form the two ordinates of the table, and the table thus consists of a modest number of intervals whose total duration defines a complete “cycle” of stimulation. The instantaneous current flow to be generated by the implanted portion is defined at the beginning of each stimulation cycle by multiplying the weighting factor stored in a particular location within the pulse table by modulation data derived from the sensed acoustic signal. Only modulation data need be sent to the implanted portion on a continuous (real time) basis for the cochlear implant system to function.

Multichannel cochlear prosthesis with flexible control of stimulus waveforms

An improved pulsatile system for a cochlear prosthesis is disclosed. The system employs a multi-spectral peak coding strategy to extract a number, for example five, of spectral peaks from an incoming acoustic signal received by a microphone. It encodes this information into sequential pulses that are sent to selected electrodes of a cochlear implant. The first formant (F1) spectral peak (280-1000 Hz) and the second formant (F2) spectral peak (800-4000 Hz) are encoded and presented to apical and basal electrodes, respectively, F1 and F2 electrode selection follows the tonotopic organization of the cochlea. High-frequency spectral information is sent to more basal electrodes and low-frequency spectral information is sent to more apical electrodes. Spectral energy in the regions of 2000-2800 Hz, 2800-4000 Hz, and above 4000 Hz is encoded and presented to three fixed electrodes. The fundamental or voicing frequency (F0) determines the pulse rate of the stimulation during voiced periods and a pseudo-random aperiodic rate determines the pulse rate of stimulation during unvoiced periods. The amplitude of the acoustic signal in the five bands determines the stimulus intensity.

Multi-peak speech processor

A method and apparatus (10) for fitting an auditory stimulation system involves, in one embodiment, coupling a programmer unit (14) to an implanted unit (46) implanted in a patient; prompting and/or assisting an operator to make and enter an objective or other measurement; receiving the objective measurements into the programmer unit; and determining an estimated threshold stimulation current for each electrode channel of the implanted unit as a function of the objective measurement In another embodiment, the method and apparatus involve coupling the programmer unit (14) to the implanted unit (46); stimulating the patient with a speech signal; and displaying, in real time, a graphical representation of the speech signal using the programmer unit Estimated and/or measured stimulation threshold levels may be overlaid on the real-time display to facilitate adjustment of the stimulation current

Programming of a speech processor for an implantable cochlear stimulator

A power control loop is established between an external control device and an implantable device so that only the amount of power needed by the implant device to sustain its present operating conditions is transmitted across a transcutaneous transmission link, thereby reducing the amount of power expended by the external control device In one embodiment, the power control loop is used with a cochlea stimulating system that includes an externally wearable signal receiver and processor (WP) and an implanted cochlear stimulator (ICS) The power control loop is provided between the ICS and the WP such that power delivered to the ICS is precisely controlled in a closed loop manner, with a variable amount of RF energy (power) being transmitted across the transcutaneous link between the WP and ICS The transmitted RF energy is received by the ICS and is converted to a voltage that is used as a power source within the ICS for stimulating electrode contacts of the ICS These contacts, when activated, require a certain amount of current that represents a power drain from the power source (ie, from the voltage derived from the transmitted RF energy) By monitoring the voltage, and transmitting a signal back to the WP from the ICS indicative of the present voltage level, the WP may supply just enough energy to the ICS to maintain the ICS power source at a specified operating voltage level, thereby resulting is less energy expended by the cochlea stimulating system

Power control loop for implantable tissue stimulator

Signal processing system for converting a speech signal into a data signal for controlling a hearing prosthesis having an implanted electrode array adapted to stimulate the auditory nerve fibers of a patient by the application of electrical currents to selected electrodes in the array. The system generates an input signal current corresponding to a received speech signal. The amplitude and frequency of the fundamental voicing component of the speech signal is approximated as are the amplitude and frequency of at least one formant of the speech signal. A programmable microprocessor produces instructions which cause the application of electrical currents to selected groups of electrodes in the array with or without delays between the stimulation of each electrode in the groups. The microprocessor is programmable with data defining a predetermined relationship between each group of electrodes and a selected range of at least one formant frequency and with data defining a predetermined relationship between another formant frequency and the delay between stimulation of each electrode in each said group based on psychophysical testing of the patient. Selection of electrodes based on the estimated frequency of the formants produces the desired percepts in the auditory-like sensations generated in the patient. The microprocessor is further programmable to produce data which determines the level of stimulation of each selected group of electrodes and determines the delay between stimulation of electrodes in each group dependent on the estimated amplitude of formants of the speech signal as well as on predetermined data relating to the sensitivity of each electrode implanted in the patient.

Speech processing method and apparatus

A signal processing system for converting a speech signal into a data signal for controlling a hearing prosthesis including an implanted electrode array adapted to stimulate the auditory nerve fibres of a patient by the application of electrical currents to selected electrodes in said array, said processing system comprising means (20, 21) for generating an input signal corresponding to a received speech signal, means (30-36) for estimating the amplitude and frequency of the fundamental voicing component of said speech signal, means (22-26, 27, 28) for estimating the amplitude and frequency of at least one formant of said speech signal, programmable means (40) for producing instruction data which in use causes the application of said electrical currents to selected groups of electrodes in said array with or without delays between the stimulation of each electrode in said groups, said programmable means being programmable with data defining a predetermined relationship between each group of electrodes and a selected range of at least one formant frequency and with data defining a predetermined relationship between another formant frequency and the delay between stimulation of each electrode in each said group based on psychophysical testing of the patient and causing selection of said electrodes based on the estimated frequency of said formants such as to produce the desired percepts in the auditory-like sensations generated in the patient, said programmable means (40) further being programmable to produce data which determines the level of stimulation of each selected group of electrodes and determines the delay between stimulation of electrodes in each said group dependent on said estimated amplitude of said formants of said speech signal as well as on predetermined data relating to the sensitivity of each electrode implanted in the patient.

Tong Y C

Papers

Speech processing method and apparatus

Improvements in speech processors