Multi-peak speech processor

• US 5,271,397 A
• Filed: 12/16/1991
• Issued: 12/21/1993
• Est. Priority Date: 09/08/1989
• Status: Expired due to Fees

• Current Assignee: Cochlear Limited
• Original Assignee: Cochlear Corporation (Cochlear Limited), University of Melbourne
• Inventors: Blamey, Peter J., Seligman, Peter M., Dowell, Richard C.
• Primary Examiner(s): Isabella, David
• Assistant Examiner(s): BURKE, ELIZABETH
• Application Number:
  US07/808,428
• Time in Patent Office: 736 Days
• Field of Search: 623/10, 623/11, 623/66, 128/642, 128/784, 128/789, 128/420.5, 128/420.6
• US Class Current: 607/137
• CPC Class Codes: A61N 1/36038 Cochlear stimulation

Abstract

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.

Claims

1. A method of processing in a speech processor an audio signal, received from a microphone coupled to the speech processor, to produce signals for stimulating a patient-implantable, tissue-stimulating, multi-channel electrode array having apical and basal regions therein and being configured to be positioned in a cochlea from a corresponding apical region of the cochlea to a corresponding basal region of the cochlea, said method comprising the steps of:

selecting a first dominant spectral peak from said audio signal from a frequency band of between 280 Hz and 1000 Hz and stimulating at least one electrode in the apical region of said electrode array corresponding to said first peak;

selecting a second dominant spectral peak from said audio signal from a frequency band of between 800 Hz and 4000 Hz and stimulating at least one electrode in the basal region of said electrode array corresponding to said second peak; and

,

extracting spectral information in at least one region of a spectrum of said audio signal and stimulating at least a first additional electrode in the basal region of said electrode array corresponding to said extracted spectral information.

2. A method of processing an audio signal as claimed in claim 1, including the further steps of stimulating second and third additional electrodes in the basal region of said electrode array, said first, second and third electrodes being stimulated using spectral energy derived from said audio signal in respective audio frequency regions of 2000 to 2800 Hz, 2800 to 4000 Hz and above 4000 Hz.

3. A method of speech coding in a speech processor an audio signal, received from a microphone coupled to the speech processor, to produce signals for stimulating a patient-implantable, tissue-stimulating, multi-channel electrode array having apical and basal regions therein and being configured to be positioned in a cochlea from a corresponding apical region of the cochlea to a corresponding basal region of the cochlea, said method comprising the steps of:

providing to a patient through said electrode array initial high frequency information from said audio signal corresponding to a normal second format peak F2 occurring within a normal range of about 800 Hz to 4000 Hz;

band pass filtering said audio signal into a plurality of bands within and beyond said normal range of said second format frequency peak F2; and

providing to the patient through said array additional high frequency information from said bands.

4. The method of claim 3, including the further steps of encoding said information derived from said audio signal into sequential pulses and applying said sequential pulses to selected electrodes of said electrode array.