Search PubMed⌕ Search

Biomedical subjects

R C Bilger

Publications and source records attributed to R C Bilger.

14 recordsLinked to original sources
PubMed1978

A comparison of the effects of filtering and sensorineural hearing loss on patients of consonant confusions.

It has been found that listeners with sensorineural hearing loss who show similar patterns of consonant confusions also tend to have similar audiometric profiles. The present study determined whether normal listeners, presented with filtered speech, would produce consonant confusions similar to those previously reported for the hearing-impaired listener. Consonant confusion matrices were obtained from eight normal-hearing subjects for four sets of CV and VC nonsense syllables presented under six high-pass and six-low pass filtering conditions. Patterns of consonant confusion for each condition were described using phonological features in sequential information analysis. Severe low-pass filtering produced consonant confusions comparable to those of listeners with high-frequency hearing loss. Severe high-pass filtering gave a result comparable to that of patients with flat or rising audiograms. And, mild filtering resulted in confusion patterns comparable to those of listeners with essentially normal hearing. An explanation in terms of the spectrum, the level of speech, and the configuration of this individual listener's audiogram is given.

Audiometry↗
PubMed1978

Galvanic disruption of vestibulospinal postural control by cochlear implant devices.

All subjects with implanted cochlear stimulators demonstrated evidence of abnormal postural stability without their stimulators activated. Instability increased when they were tested with cochlear stimulation units turned on, and additional instability was demonstrated in four of these subjects when tested in noise. These findings suggest that the electrical stimulation delivered by the cochlear prosthesis is not limited to the auditory system. The precise characteristics of electrical stimulation devices designed for stimulations limited to the cochlea and their spurious effects upon motor performance should be investigated. The design of future intralabyrinthine auditory electrical prostheses must include hardware designs and stimulus paradigms that avoid undesirable vestibular system stimulation.

Adult↗
PubMed1976

Temporal acuity in listeners with sensorineural hearing loss.

Temporal acuity, the minimum time interval within which the auditory system can discriminate the order of auditory events, was measured for three listeners with normal hearing and for 10 listeners with sensorineural hearing loss. Eight of the 10 listeners with sensorineural loss showed better temporal acuity for conditions with greater loss. The remaining two listeners showed the opposite effect. The temporal acuity results are not well correlated with either speech discrimination scores or measures of recruitment. The temporal acuity results do appear to be correlated with results observed in studies of temporal integration or brief-tone audiometry. Listeners with sensorineural loss tend to have both poor temporal integration and good temporal acuity. This suggests that the two temporal measures may reflect a single time constant in the auditory system.

Adult↗
PubMed1976

Consonant confusions in patients with sensorineural hearing loss.

Consonant confusion matrices were obtained from 22 outpatient listeners with sensorineural hearing loss for four sets of CV and VC nonsense syllables, presented monaurally at SRT + 40 DB. Testing was typically conducted for six hours on each of two separate days. Overall performance and patterns of confusions were stable over time. Analysis of the matrices in terms of phonological features indicated that the patterns of consonant confusions varied both with degree and configuration of the subject's loss. Scaling of intersubject similarity using a pairwise multidimensional scaling analysis resulted in consistent classification of subjects according to audiometric configuration into three groups-essentially normal hearing, flat or rising audiograms, and high-frequency hearing losses.

Adult↗
PubMedDate not supplied

Auditory prostheses in perspective.

The results of the evaluation of subjects presently fitted with internal auditory prostheses are summarized. Based on these results, the role of single-channel prostheses as a treatment for acquired deafness is discussed in terms of the auditory expectation for a single channel and of subject selection.

Cochlea↗
PubMedDate not supplied

Present audiologic status of subjects implanted with auditory prostheses.

Audiological testing indicated that all of the subjects had profound sensorineural hearing losses. In 12 of the 13 subjects, this profound hearing loss was bilateral. The 13th subject, however, had useable hearing in his unimplanted ear. Tympanometric testing gave no evidence that implant surgery had disrupted middle ear function.

Audiometry↗
PubMedDate not supplied

Electroacoustic measures of present prostheses.

To determine the electrical nature of the signals delivered to the electrode implanted in scala tympani, extensive electroacoustic measures were made on a House-Urban stimulator, both in a closed, acoustic system (hearing-aid box) and in the sound field. For these measures, the external coil was separated from the internal coil by plexiglass, and the internal coil was loaded resistively. Illustrations of the signal delivered to the electrode are provided.

Cochlea↗
PubMedDate not supplied

Hearing performance with the auditory prosthesis.

With their prostheses activated 12 of 13 subjects were able to respond to sound (bands of noise) at intensities (35-65 dB SPL) that typically arise in the normal acoustic environment. While this "hearing" did allow them to be aware of speech, it did not permit them to understand speech. On the other hand, this "hearing" does seem to help them with identification of common environmental sounds and with lipreading, within the context that those abilities were tested here.

Audiometry↗
PubMedDate not supplied

Subject acceptance of implanted auditory prosthesis.

Each of the 13 subjects was interviewed, in a structured context, to determine their estimate of the value of the prosthesis to their daily life. The subjects who used their prostheses eight or more hours a day reported it to be more valuable in their daily living than did those who used it less than eight hours a day. The fulltime users reported that the prosthesis is most helpful to them as an adjunct to lipreading. All of them thought the prosthesis valuable in terms of "hearing" environmental sounds. While all of them reported noisy environments to be bothersome, the fulltime users did not turn off their stimulators in noise. Only two subjects, both infrequent users of their prostheses, reported that they would not undergo implant surgery again.

Cochlea↗
PubMedDate not supplied

Psychoacoustic evaluation of present prostheses.

A battery of psychoacoustic tests, designed to specify auditory discriminations possible with present, single-channel auditory prostheses, was administered successfully to 12 of the 13 subjects. While no subject was able to perform all discriminations required by this battery of tests, there was no discrimination that at least one subject did not perform successfully. The typical subject could 1) discriminate intensity differences within normal limits for frequencies below 1000 Hz; 2) discriminate frequency differences quite normally at 125 and 250 Hz, but not at all at 1000 or 2000 Hz; 3) discriminate differences in signal duration, temporal patterning (rhythm), and spectrum (e.g., tone vs narrow-band noise); and 4) discriminate between pairs of synthesized vowel-like sounds. The results of masking experiments could only be interpreted in terms of intensity discrimination. Several subjects were able to relate stimulus intensity to loudness for low-frequency sounds; and they could relate stimulus frequency to pitch for signals below 25 Hz. The intelligibility of the subjects' speech was found to improve when their prostheses were activated.

Auditory Threshold↗