Abstract: An active in the ear hearing protector having an ear piece (13) and a casing (12) attachable to the ear piece, the ear piece being positionable in the ear canal of a user so as to peripherally acoustically seal the ear canal and such that the attached casing (12) is positioned externally of the ear canal. The casing (12) incorporates a microphone (14) for receiving external acoustic sound signal and a signal processing circuit (15) for receiving electrical signal from the microphone and correspondingly causing a loudspeaker (16) in the casing to generate sound signal for direction down a tube (34) extending through the ear piece to be transmitted to the ear canal. The electrical circuit (15) is arranged to limit the electrical signal delivered to drive the loudspeaker whereby to limit the sound pressure of sound signal delivered from the loudspeaker to the ear canal via the tube (34).

Abstract: A time-multiplexed switched capacitor circuit in which certain capacitors are shared during local time periods of a global time period to allow the total capacitance of the circuit to be reduced. Corresponding savings in chip area in an integrated circuit implementation and component savings in a discrete implementation may be achieved. The invention is particularly applicable to a multiplexed circuit comprising an array of capacitors including first and second common capacitors and first and second pluralities of capacitors. The capacitors may be switched into and out of the multiplexed circuit during different local time periods. The first common capacitor may be switched into the circuit when any one of the first plurality of capacitors is involved in the operation of the multiplexed circuit thus reducing the size of that one capacitor of the first plurality of capacitors.

Abstract: 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.

Abstract: A system for converting a speech signal into a data signal for controlling an implantable stimulation electrode array hearing prosthesis. An input speech signal is passed through three circuit arms, comprising filter circuits, zero crossing counter circuits and RMS measuring circuits (3-13), for producing signals representing amplitude and frequency of the fundamental voicing component and the first three formants of the speech signal. Computer (14) is programmed with a patient's psychophysical data, and determines the manner of stimulation of the electrodes by ranking the sharpness of the electrodes and assigning sub-bands of the second formant frequency range to particular electrodes. Also, the voiced or unvoiced nature of the signal is determined by comparing the fundamental and second formant components. The output signal passed through a data formatter (15) and transmitter (16) has both formant and prosodic information whereby the production of confusing percepts is avoided.

Abstract: A prosthesis and specifically an aural prosthesis which includes an implantable component which is in connection with means which can selectively stimulate neural endings the component being arranged to receive a signal from an extension component which converts a parameter into a transmittable form and which includes a transmitter, the signal from the transmitter received by the implanted component which resolves the signal into groups of two components which can selectively stimulate the neural endings, the stimulation to each ending being independent to stimulation of each other neural ending in both intensity and phase.