Reflex modulation: a hearing test for the difficult-to-test.

This study was designed to determine the effectiveness of reflex modulation (RM) audiometry in assessing the hearing sensitivity of difficult-to-test subjects. RM describes the inhibitory effect of a tone upon a subsequently elicited eyeblink reflex. Five ENT subjects were referred to the University of Kansas audiology clinic because of medicolegal problems or doubts regarding their hearing status. After conventional pure tone and speech audiometry had produced equivocal results, the subjects were tested by RM. The study indicates that RM is effective as an objective test of hearing for these subjects. Since RM sensitivity is not frequently dependent, it has a potential role as an adjunct to the brainstem evoked response (BSER) for testing low frequencies.

The effects of age, sex, hearing loss and water temperature on caloric nystagmus.

Seventy five subjects ranging in age from 18 to 87 years received warm and cool caloric irrigations. Nystagmus was recorded and latency, duration, amplitude, frequency and speed of the slow component were measured. The effects of age, hearing loss, sex and water temperature were evaluated. Significant differences were found in cool water durations. Significant differences were found as a function of age for all parameters in warm water calorics. Response duration was not found to be significantly correlated to speed of the slow component in cool calorics.

Effects of six conditions of ocular fixation on caloric nystagmus.

Caloric tests were performed on 20 normal volunteers under the following six conditions of ocular fixation: (1) eyes open with lighted +20-diopter lenses; (2) eyes open with lighted +20-diopter lenses plus strobe lighting; (3) eyes open in darkness; (4) eyes closed in darkness; (5) eyes closed in a dimly lighted room; and (6) eyes open with unlighted +20-diopter lenses plus strobe lighting. Latency, amplitude, frequency, duration, and speed of the slow component were measured from a permanent recording. Significant differences were found between the lighted +20-diopter lens conditions and all others for all variables except latency. Tests performed with lighted +20-diopter lenses should be cautiously interpreted due to the noticeable response suppression noted in these conditions. The present procedure of performing caloric tests with the eyes closed in a dimly lighted room was found to be unqeustionably preferable.

An evaluation of speech audiometry by bone conduction in hearing-impaired adults.

Pure-tone thresholds, speech reception thresholds (SRT), and speech discrimination scores (DS) were obtained by ac and bc on 20 normal-hearing and 30 hearing-impaired adults. Correlations between the SRT and pure-tone thresholds (ave. of .5, 1, and 2 kc/s) were significant by both ac and bc. Correlations between DS by ac and bc were also highly significant, indicating the value of the bc DS in specific difficult cases. The clinical observation was confirmed statistically of decreasing DS with increasing sensorineural hearing loss.

A study of five parameters of calorically-induced nystagmus in the clinical situation.

Latency, duration, and amplitude of response, frequency of nystagmic beats, and speed of the slow component of calorically-induced nystagmus were studied by ENG in 14 normal-hearing adults. Attention was directed toward differences as a function of stimulus temperature (30 degrees C vs 44 degrees C) and side of stimulation. Nystagmus amplitudes were significantly larger from R ear as compared to L ear irrigations, and from cool as compared to warm. Ssc's from cool irrigations were also significantly larger than from warm. A series of t-tests computed for correlated samples indicated that the R ear 30 degrees irrigation, which was the first stimulus for all Ss, was responsible for the significant differences. Implications of the need for research on caloric interstimulus intervals and vestibular response fatigue were presented, and a procedure outlined to avoid erroneous results in caloric testing.

Analysis of optokinetic and eye tracking data on normal subjects.

This study was undertaken to determine the incidence of abnormal eye tracking patterns in normal subjects and to compare the optokinetic (OPK) response of normal subjects using a nystagmographic gonioscope (Nystagmotrac) and Coats's type of OPK drum. Eye movement was recorded by means of an electronystagmographic (ENG) recorder, and the speed of the slow component was computed for the OPK response. The eye tracking test showed a high rate of abnormality among our subjects. Optokinetic testing revealed highly symmetrical responses for all subjects.

Unreliability of half-list discrimination tests.

The present study was undertaken to investigate the reliability of the half-list forms of the CID W-22 and the NU no. 6 auditory discrimination tests with both normally hearing and sensorineurally impaired subjects. For each group of subjects, both the first half-lists and the whole-lists were scored. Analysis of the data indicated that the half-list forms of the tests were not as reliable as sometimes suggested in the literature. Further, the half-list form of the NU no. 6 was demonstrated to be not as reliable as the half-list form of the CID W-22 even before the correction coefficient was applied.