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Biomedical subjects

W O Olsen

Publications and source records attributed to W O Olsen.

At least 37 records · Page 2Linked to original sources
PubMed1983

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.

Adult↗
PubMed1983

Effects of intensity variations on auditory processing in aphasia. II. Different intensities at each ear.

A neurologic extinction model was applied to the auditory-processing disorders evidenced by 10 persons with aphasia. This model suggests that messages travel faster to the intact hemisphere, where they are more differentiated and articulated, than to the affected hemisphere. This leads to extinction and interference of the message. To overcome this extinction, the stimulus intensity was raised by 15 or 30 dB to one ear at a time. The stimuli were a cortical auditory-evoked response (AER) measure, a nonverbal intensity sequencing test (NVIST), a minimally varied phoneme-in-word discrimination and sequencing test (MVPT). and a semantic-syntactic level test (RTT). The results suggest that intensity can be traded for time in quantities large enough to overcome the extinction interference of auditory stimuli. Although some statistically significant results and meaningful trends toward improved performance were evident on the NVIST and the MVPT, a unilateral increase of stimulus intensity did not prove to be a potent mechanism for improving auditory comprehension. Sentence length material was not affected in either direction by selective amplification. The role of the left ear/right hemisphere as a facilitator of processing for linguistic and nonlinguistic material was suggested by the results of this study.

Adult↗
PubMed1983

Auditory brain-stem response and acoustic reflex test.

Auditory brain-stem response (ABR) and acoustic reflex test (ART) results were reviewed for 30 patients with cerebellopontile angle tumors and for 30 patients without tumor. Patients included in the nontumor group were selected to match the audiometric configurations for individual patients in the tumor group. The ABR waveforms were abnormal for all but one of the patients with tumor and for seven of the patients without tumor. The ART results were abnormal for 25 of the patients with tumor and two of the patients without tumor. Patients without tumor yielding abnormal ABR results usually had more severe hearing losses than the patients without tumor who demonstrated normal ABR waveforms. The ABR and ART merit continued use in the audiologic examination of patients suspected of having retrocochlear lesions, but obviously, degree of hearing loss and other medical information must be considered also when retrocochlear lesions are suspected.

Adolescent↗
PubMed1981

Ipsilateral auditory pathway suppression in dichotic CV speech perception: evidence from error analysis.

The exact nature of ipsilateral auditory pathway suppression under dichotic stimulation remains controversial. To help resolve this controversy, the distinctive feature confusions (blend vs nonblend errors) made on a dichotic listening CV test by two hemispherectomees were analyzed. Results support ipsilateral auditory pathway suppression under dichotic CV stimulation. Ipsilateral auditory pathway suppression is discussed in terms of stimulus specificity, subject, and task difference.

Adult↗
PubMed1979

Bone conduction calibration: current status.

Attempts to specify normal threshold sensitivity by bone conduction have been unsuccessful because of problems in obtaining reliable measurements from commercially available artificial mastoids. Recent design modifications incorporated in the Bruel and Kjaer 4930 artificial mastoids have resulted in greater uniformity among these units. However, the new design has resulted in impedances that are higher than those recommended in current standards. Bone-conduction thresholds referenced to measurements made on B & K 4930 artificial mastoids with the new design were performed on 60 normal listeners by three participating laboratories. The results are reported for consideration in the development of a reference threshold for hearing by bone conduction.

Acoustic Impedance Tests↗
PubMed1978

Signal monitor for audiometry.

Conventional volume unit (VU) and auditory monitors of signals generated by or fed through an audiometer do not allow monitoring of the signal after the attenuator or output selector. An amplifier-compressor circuit has been designed and constructed which allows auditory monitoring of the electrical signal at the transducer. The circuit and its use are described.

Amplifiers, Electronic↗
PubMed1975

Bekesy test results in patients with eighth-nerve lesions. Forward reverse- and fixed-frequency tracings.

Sweep-frequency Bekesy tracings, both forward (low to high frequency) and reverse (high to low frequency), as well as fixed-frequency tracings, were obtained from 18 patients who had eighth-nerve tumors (subsequently confirmed surgically). In general, reverse-sweep frequency tracings revealed greater adaptation for continuous tone stimuli than did forward-sweep frequency tracings. However, if a search for excess adaptation (greater than 20 dB) is the sole purpose for administering Bekesy audiometry to a given patient, then fixed-frequency tracings yield adequate differential information.

Adaptation, Physiological↗
PubMed1975

Acoustic reflex and reflex decay. Occurrence in patients with cochlear and eighth nerve lesions.

Acoustic reflex and reflex decay tests were administered to 50 normal ears, 50 ears with hearing loss due to noise trauma, 50 ears that had Meniere disease, and 28 ears that had involvement of the eighth nerve. In one normal ear, ten noise trauma ears, 11 Meniere disease ears, and 24 eighth nerve lesion ears to reflexes or reflex decay that were suggestive or retrocochlear lesions were observed. Acoustic reflex and reflex decay results are also compared to tone decay results for these patients.

Acoustic Stimulation↗
PubMed1975

Heredopathia atactica polyneuritiformis (phytanic acid storage disease). A new case with special reference to dietary treatment.

A 33-year-old man with Refsum disease exhibited clinical features of night blindness, dysequilibrium, hearing loss, itchy dry skin, symmetrical polyneuropathy, distal muscle weakness, pes cavus, and hammer toe. His total serum protein was increased, nerve conduction velocities were slow, and serum phytanic acid levels were high. Dietary restriction of phytol resulted in a decrease in serum phytanic acid without any visual and autitory changes; however, coordination, skin lesions, and nerve conduction velocities definitely improved.

Adult↗