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Biomedical subjects

R W Stream

Publications and source records attributed to R W Stream.

10 recordsLinked to original sources
PubMed1991

Discrimination of short duration tones by elderly subjects.

The ability to discriminate the frequency of short duration tone pulses was investigated with 28 elderly subjects. In a previous study, Cranford, Stream, Rye, and Slade (1982) found that subjects with unilateral temporal lobe lesions were impaired in their ability to discriminate small changes in the frequency of such signals at ears located opposite the lesions. In the present study, although considerable intersubject variability was observed, several subjects exhibited deficits on the brief tone frequency difference limen test similar to that observed with temporal lobe lesion patients, but present at both ears. The occurrence of a discrimination problem was significantly correlated with subject age, but not with audiometric hearing level, thus suggesting the sensitivity of the test to the central neural effects of aging.

Acoustic Stimulation↗
PubMed1982

Detection v discrimination of brief-duration tones. Findings in patients with temporal lobe damage.

Based on earlier experiments with cats, we have developed two new hearing tests to evaluate the ability of patients with temporal lobe damage to discriminate tones of short temporal duration. Earlier published studies suggested that patients exhibit notably increased thresholds for detecting tone pulses shorter than 200 ms in length when the signals are presented to the ear located contralateral to the damaged hemisphere. Our experiments with cats indicated that auditory cortex lesions had no effect on the cats' ability to detect brief tones but did impair their ability to discriminate small changes in the frequency of such signals. In giving the brief-tone tests to seven patients with temporal lobe damage, we found a similar behavioral dissociation. All patients exhibited normal detection thresholds in conjunction with substantially elevated frequency difference limina.

Adolescent↗
PubMed1980

Visual tracking of auditory stimuli.

A white noise sound stimulus was emitted successively in an anechoic chamber across 24 loudspeakers equally spaced in the horizontal plane in a semicircle with diameter of 11 ft. Eye movements produced by each of 20 normal-hearing young adults in the center of this arc who tracked the sound at 10 different velocities (15--180 degrees/sec) were recorded with standard ENG methods. During each rotating cycle of the stimulus the eyes were able to follow the sound with discrete saccades, but did not produce nystagmic-like movements. Increased stimulus velocity resulted in (1) diminution of the amplitude of the tracking cycles, (2) decrease in the number of saccades, and (3) increase in the average velocity of the eye. Ss performed better with lights on than off. The additional quantitative findings from the present study further indicate the limitation in the ability of human Ss to localize a moving acoustic source in space.

Acoustic Stimulation↗
PubMed1978

The biphasic acoustic reflex: a new perspective.

The anatomic, neurologic, and physiologic characteristics of the middle ear structures have created confusion concerning the nature of the intraaural muscle reflex. After reviewing the relevant literature, we correlated this information with our studies of human temporal bones and computer analyses of the acoustic reflex responses of individuals with normal hearing. Our hypothesis is that although the stapedius is the initiator of the reflex and the primary contributor to ossicular chain fixation, the tensor tympani is responsible for the major observed response. The negative deflection present in normals tested on the impedance bridge is caused by the stapedius, whereas the large positive deflection is the result of the tensor tympani contraction. We postulate that proprioceptive feedback mechanisms located within the stapedius muscle and tendon permit and/or initiate tensor tympani contraction during acoustic stimulation.

Acoustic Stimulation↗
PubMed1975

Otoadmittance measurements in cases of dual ossicular disorders.

Audiologic evaluations, including otoadmittance measurements, were obtained on two patients, each of whom had dual, series-connected disorders of ossicular fixation and disarticulation. In one case, the disarticulation was the lateral-most disorder; in the other case the fixation was the lateral-most disorder. In both cases, it was the lateral-most disorder that had the dominant effect on the otoadmittance of the tympanic membrane, due to the fact that the sites of the two disorders were connected in series with the tympanic membrane.

Adult↗
PubMedDate not supplied

Emerging characteristics of the acoustic reflex in infants.

One hundred ninety-nine infants (birth to 15 weeks) were administered an impedance battery to describe emerging characteristics of the acoustic reflex in this age range. Tympanometry results suggest that the middle ear system changes from a highly flaccid state at birth to a relatively normal compliance by 15 weeks. Acoustic reflexes were observed infrequently in the newborn population and gradually increased as a function of age, but never exceeding 43% of the ears tested. A conservative approach regarding the relevance of the presence of the reflex in young children is warranted.

Acoustic Impedance Tests↗