Biomedical subjects

D Van Compernolle

Publications and source records attributed to D Van Compernolle.

3 recordsLinked to original sources

PubMed1990

Hearing aids using binaural processing principles.

The performance of normal human hearing in noisy circumstances is helped considerably by its ability to focus on a specific sound source. This ability is derived from the binaural nature of hearing. In this paper we present signal-processing techniques that can partially replace the binaural hearing in situations where a monaural hearing aid is used (monaural deafness, cochlear implants). First, simple noise cancellation and beam forming solutions, which are applicable to speech, are presented. Then full adaptive filter versions and a successful combination of both are proposed. A key element to the success of all these algorithms is the use of a noise versus speech discrimination criterion on which basis selected parts of the adaptive filter structure are adapted at any given moment.

Algorithms↗

PubMed1987

Pitch perception by cochlear implant subjects.

Direct electrical stimulation of the auditory nerve can be used to restore some degree of hearing to the profoundly deaf. Percepts due to electrical stimulation have characteristics corresponding approximately to the acoustic percepts of loudness, pitch, and timbre. To encode speech as a pattern of electrical stimulation, it is necessary to determine the effects of the stimulus parameters on these percepts. The effects of the three basic stimulus parameters of level, repetition rate, and stimulation location on subjects' percepts were examined. Pitch difference limens arising from changes in rate of stimulation increase as the stimulating rate increases, up to a saturation point of between 200 and 1000 pulses per second. Changes in pitch due to electrode selection depend upon the subject, but generally agree with a tonotopic organization of the human cochlea. Further, the discriminability of such place-pitch percepts seems to be dependent on the degree of current spread in the cochlea. The effect of stimulus level on perceived pitch is significant but is highly dependent on the individual tested. The results of these experiments are discussed in terms of their impact on speech-processing strategies and their relevance to acoustic pitch perception.

Acoustic Stimulation↗

PubMedDate not supplied

Comparison of different speech processing strategies on patients receiving the same implant.

Two subjects with transcutaneously connected 8-electrode scala tympani implants were given subsets of the Minimal Auditory Capabilities test during stimulation with five speech processing strategies--two single channel and three multichannel. While there were significant (p = 0.05%) scores on some items with all types of stimulation, one subject did as well with single channel analog as with multichannel stimulation. She is an enthusiastic full-time user of single channel stimulation. The other, a nonuser of the same device, preferred (and performed better with) one of multichannel stimulation. This is an interim report because neither subject has yet had the opportunity of nonlaboratory use of the multichannel schemes.

Adult↗