Biomedical subjects

J A Kuzma

Publications and source records attributed to J A Kuzma.

3 recordsLinked to original sources

PubMed1989

Implantation of the Melbourne/Cochlear multiple-electrode extracochlear prosthesis.

The Melbourne/Cochlear multiple-electrode extracochlear implant is designed for deaf patients who are unsuited to multiple-electrode intracochlear implantation. The implant consists of a receiver-stimulator package connected via a lead wire assembly to six individual stimulating electrodes. There is a choice of two alternative surgical procedures, both of which are via a combined middle ear approach using anterior and posterior tympanotomies. Four active electrodes shaped into compressible platinum-iridium soft-balls are fed through the mastoid cavity and across the facial recess, and placed into cavities that are made over the cochlear turns that project to the medial wall of the middle ear. One hard-ball active electrode is placed into the round window niche. One hard-ball reference electrode is placed into the hypotympanum. An additional electrode wrapped around the lead wire assembly can be used as an alternative reference electrode. A specially designed insertion needle facilitates the placement and the fixation of the soft-ball electrodes.

Cochlear Implants↗

PubMed1984

The nucleus multi-channel implantable hearing prosthesis.

The Nucleus Multi-channel Implantable Hearing Prosthesis was developed in conjunction with the University of Melbourne. A 22 channel flexible electrode array is inserted into the cochlea through a round window opening. A cable leads from the electrode array to a demountable connector mounted on the Receiver-Stimulator unit (RSU). A custom CMOS integrated circuit is mounted inside the hermetically sealed titanium and ceramic RSU which is encased in silicone rubber and measures 34.5 mm diameter and 10.5 mm thick. Biphasic current pulse stimuli can be delivered to any selected electrode pairs at rates in excess of 1 kHz. A pocket-sized speech processor extracts spectral information from the incoming acoustic signal, and encodes stimulus information onto the single RF power/data signal transmitted to the RSU through the skin. The Speech Processor includes electronic memory circuits which are programmed with the information mapping acoustic parameters to stimulation parameters for each electrode for each patient. This MAP is established as a result of psychophysical experiments performed by the audiologist using the Diagnostic and Programming System based on a customized microcomputer.

Cochlear Implants↗

PubMedDate not supplied

A multi-channel hearing prosthesis for profound-to-total hearing loss.

A multi-channel cochlear implant hearing prosthesis providing 22 separate channels of stimulation has been developed. The electronics for the implantable receiver-stimulator have been incorporated on a single chip, using digital circuits and employing CMOS technology. The chip is enclosed in a titanium capsule with platinum/ceramic electrode feed-throughs. A pocket-sized speech processor and directional microphone extract the following speech parameters: signal amplitude, fundamental frequency and formant frequency. The fundamental frequency is coded as electric pulse rate, and formant frequency by electrode position. The speech processor has been realized using hybrid circuits and CMOS gate arrays. The multi-channel prosthesis has undergone a clinical trial on four postlingually deaf patients with profound-total hearing losses. The speech perception results indicate that they were able to obtain open-set speech recognition scores for phonetically balanced words, CID sentences and spondees. In all cases the tests showed significant improvements when using the cochlear prosthesis combined with lipreading compared to lipreading alone.

Adult↗