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Biomedical subjects

T Spillmann

Publications and source records attributed to T Spillmann.

31 records · Page 2Linked to original sources
PubMed1984

Results and perspectives with extracochlear round window electrodes.

The results obtained with implanted electrodes at the round window are comparable to results with electrodes in the scala tympani or in the hearing nerve in respect to frequency and amplitude resolution with pulsatile and sinusoidal stimulation (with considerable interpatient variations). Although the subjective quality of the perceived sounds is expected to vary depending on the stimulation site, it seems that timing effects of electrical stimulation may play a major role in pitch perception as required for voice and sound recognition or prosody identification. Our technique is a safe procedure involving only routine middle ear surgery to place the induction coil within the mastoid bone and to put an electrode at the round window margin. By an external stimulator, sounds are transformed to electrical stimuli suited to excite surviving fibers of the cochlear nerve. This helps the patient to communicate and provides some basic cues for speech discrimination.

Adult↗
PubMed1983

Clinical results with cochlear prostheses. Introductory remarks.

Reports on results of cochlear prostheses have left open many questions. More information on implanted persons is needed to counterbalance the fact of small sample size and heterogeneous makeup of the implanted patient groups. The precise use of audiological and phonetic terms in reporting on postimplantation test results could help to clarify the influence of different electrode setups, electrode locations, and coding features, and to make results comparable between different centers.

Auditory Threshold↗
PubMed1983

Computerized testing of signal-encoding strategies with round-window implants.

After extensive testing of a patient with two bipolar modiolar electrodes connected to a percutaneous plug in 1977, we provided four patients with a single-channel monopolar round-window electrode connected to a tuned radio-frequency receiver coil. Loudness and pitch discrimination and results of psychophysical scaling experiments of extracochlear electrodes are comparable to those with intracochlear stimulation. Extensive testing with a computerized test system and with tape-recorded and live speech material showed that accurate vowel and speaker identification by stimulation alone is possible and that discrimination by lipreading is considerably improved. Interactive training sessions further improve discrimination results. Different signal-encoding algorithms can be used to generate in real time stimulation signals from prestored speech parameters (such as pitch, gain, formants, and zerocrossing intervals).

Adult↗
PubMed1980

Encoding and decoding of auditory signals in relation to human speech and its application to human cochlear implants.

A description of the optimal electrode and stimulus configuration, based on mathematical model simulation of (1) the mechanical conduction and (2) the mechanoelectrical transduction of the middle and inner ear, will be presented. It is assumed that a sensorineurally deaf patient, whose auditory nerve is at least partially intact, will be able to hear and understand, when an activation pattern in specific groups of remaining fibers of the hearing nerve can be reproduced in a manner equivalent to normal hearing. The placement of 2 bipolar concentric electrodes in the modiolus of the basal and middle cochlear turn in a deaf patient has provided the opportunity for testing of electrical hearing thresholds, differential thresholds, and electrode impedance changes over a 5-month period, with direct access to the electrodes through a skin window. The stimulator was housed in a pocket case to provide easy use in a daily environment. Bipolar pulses of 0.02-1.0 ms were triggered either by zero crossings or by a speech envelope controlled oscillator. It was found that loudness should be encoded by pulse amplitude or duration rather than by pulse repetition rate, since the charge per pulse was the primary variable of loudness sensation. The periodicity hearing allowed for electrical differential thresholds equivalent to or lower than the acoustical ones in normal persons in the 80- to 150-Hz region. For the optimal coding of speech, a multichannel system of 4-10 electrodes each for different nerve fiber groups will be necessary.

Cochlear Implants↗
PubMed1979

[The prognostic value in tympanoplasty surgery of eustachian tube function tests (author's transl)].

A study was undertaken to test the validity of preoperative Eustachian tube ventilation measurements in 107 patients with conductive deafness and chronic middle ear disease. By standard static aspiration and deflation tests and with the Valsalva probe correlations were found in some patients between tubal function and the extent of middle ear damage as shown by the air-bone gap on audiometry and the findings at operation. However no prognostic information was evident with these measures since no relationship existed between tubal function and operative success as judged by closure of the air-bone gap or by healing of the tympanic membrane defect.

Ear Diseases↗
PubMed1978

[Electrical stimulation of hearing in humans: a survey of the actual state of development of an implantable prosthesis for sensorineural deafness (author's transl)].

Recent clinical results show that electrical excitation of hearing sensations with implanted electrodes in the inner ear can be successful in suitable deaf persons. A critical literature review shows that some results have been described too vaguely and that there still exist numerous methodical and technical deficiencies. Even with multichannel stimulation, true tonotopical hearing could not be achieved. Periodicity hearing alone is not sufficient for the discrimination of one-syllable words. However, most deaf persons fitted with surgically implanted electrodes judged the new hearing sensations as being agreeable and quite useful. There seem to be no long term harmful effects of these implants upon the state of the acoustic nerve. However there are still a series of basic questions in auditory physiology pending which can only be solved through intensive collaboration of the clinical disciplines involved.

Animals↗