Wayne O. Olsen

Masking Level Differences Encountered in Clinical Populations

Methods for measuring masking level differences (MLDs) at 500 Hz and for spondees were used with 290 subjects: 50 persons with normal hearing and 240 patients with various diseases. Of particular interest was whether techniques currently in clinical use could be used with ease, dispatch, and profit in determining MLD size. The methods selected, which were variations of Békésy audiometry and speech reception threshold procedures, proved clinically feasible. Results revealed differences in behavior from one group of subjects to another. Although MLDs were not affected by cortical lesions, they were very often abnormally small for patients with eight-nerve tumor, Meniéres disease, or multiple sclerosis. The high incidence of abnormally small MLDs in populations with normal sensitivity to pure tones and speech but with evidence of subcortical central lesions, such as patients with multiple sclerosis, suggests that the MLD tasks can be of diagnostic value in detecting retrocochlear lesions. However, in persons with hearing loss or significant interaural differences in threshold sensitivity, or both, the MLD tests are not always reliable in differentiating cochlear from retrocochlear disease.

Speech Discrimination In Quiet And In White Noise By Patients With Peripheral And Central Lesions

Speech-discrimination scores in quiet and in white noise (O dB S/N ratio) were obtained from six groups of subjects. Differences of 40% or more between scores in quiet and in white noise were observed for less than 1% of the normal ears tested but were found for 8.0% of ears with noise trauma, 48% of ears with Menieres disease, 62% of ears with subsequently surgically confirmed 8th-nerve tumors, 14% of ears of patients with multiple sclerosis, and 42% of ears contralateral to the lesion in patients with temporal-lobe damage.

Comparison of monaural and binaural hearing aid use on a trial period basis

Thirty hearing-impaired patients compared monaural and binaural hearing aid use for a period of 4 weeks. Most of them preferred binaural hearing aids in quiet situations, but monaural hearing aids in noisy environments. Follow-up at 6 months revealed that 17 had purchased monaural hearing aids, 8 had purchased binaural hearing aids.

Dichotic test results for normal subjects and for temporal lobectomy patients.

Test results obtained with Dichotic Consonant-Vowel (CV) test materials are reported for 50 normal subjects as well as for a total of 67 patients who underwent removal of the anterior portion of the right or left temporal lobe for control of seizures. All patients were tested before and after surgery. Results demonstrated that not all patients with temporal lobe seizures with subsequent temporal lobectomy demonstrated performance below the lower limits of normal established by the sample of normal subjects. Comparison of Dichotic CV and Staggered Spondaic Word test results is made on a subset of the patient population.

Auditory Brainstem Responses as a Function of Average Hearing Sensitivity for 2 000-4 000 Hz

Average hearing thresholds for 2,000, 3,000 and 4,000 Hz and ABR results were analyzed for 290 patients having some degree of cochlear hearing loss. As average hearing sensitivity in the 2,000- to 4,000-Hz range became poorer, the incidence of abnormal auditory brainstem responses (ABR) increased. When the 2,000-Hz threshold sensitivity was 0-40 dB and the three-frequency average hearing loss was less than 50 dB, nearly 80% of ABR tracings were normal. Steeply sloping audiograms above 2,000 Hz increased the percent of abnormal ABR results.

Four-Channel ABR RecordingsConsistency in Interpretation

Simultaneous four-channel (ipsilateral, contralateral, horizontal, and noncephalic) ABR recordings were reviewed by three audiologists for 187 ears of nontumor patients, and 13 ears of patients hav...

Effects of Intensity Variations on Auditory Processing in Aphasia I. Equal Intensities at Each Ear

Clinical observations have led several authors to suggest that talking louder improves auditory comprehension for the aphasic patient, while others suggest that it does nothing to help comprehension. To clarify these observations under experimental conditions, four measures of auditory processing (cortical-evoked responses, nonverbal intensity sequencing, phoneme in word discrimination and sequencing, and a semantic-syntactic measure of comprehension) were used in diotic presentation of stimuli to 10 aphasic subjects with left temporal lobe damage. The stimuli were presented at 70, 85, and 100 dB SPL. Results suggest that a simple diotic (true binaural) increase of stimulus intensity is not a potent variable for influencing auditory processing in patients with aphasia. Although a few subjects improved their performances on selected levels when stimulus intensity was increased, the performances of others decreased. Auditory-evoked response (AER) latencies and amplitudes generally were not significantly different between the damaged and intact hemispheres. The time-intensity trading function was demonstrated with the AER, particularly for the N2 component. The ear with the greatest advantage on dichotic listening was contralateral to the lesion and was contralateral to the hemisphere that had the shorter P1 latencies, longer N2 latencies, and smaller AER amplitudes.

Penetrating injury to the brainstem after a nailgun accident: a case study.

Nonfatal penetrating injuries to the brainstem offer a unique opportunity to assess subcortical auditory pathway function. A case study of a patient suffering a severe nailgun accident is presented. Hearing sensitivity and acoustic reflexes were normal bilaterally, but word recognition was reduced for one ear. Auditory brainstem response results indicated waves I-IV were present bilaterally, but wave V was absent bilaterally. Results of vestibular findings indicated central pathology also. Results of audiologic, vestibular, radiologic, neurologic, and physical medicine examinations are discussed.

Acoustic reflex decay in 10 seconds and in 5 seconds for Meniere's disease patients and for VIIIth nerve tumor patients.

Acoustic reflex and reflex decay results for 58 patients having Menieres disease and for 58 patients having VIIIth nerve tumors were reviewed. Reflex decay was analyzed relative to decay in the first 5 sec as suggested by Anderson et al. (2) and over the full 10 sec of the stimulus as described by Jerger et al. (5). When reflex decay was observed, decay to one-half or less amplitude almost always occurred during the first 5 sec of the 10-sec stimulus.

Consistency in Latency Measurements and Interpretation of ABR Tracings

Multichannel ABR recordings for 30 otoneurologic patients were reviewed independently by three audiologists to assess interjudge consistency in determining absolute latencies and overall interpreta...