RESEARCH IN SENSORY THRESHOLD MEASUREMENT.
Abstract
The report describes studies of auditory threshold with a special purpose average response computer. The first section describes the development of the equipment used in early phases of the study. Three special purpose analog computers are described, and block diagrams provided. The second section summarizes a number of unpublished studies. They detail the effects of various stimulus parameters upon the shape of the evoked waveform; tone bursts produce greater amplitude than clicks; low frequency tone burst produce greater amplitude than high frequency tone bursts; increasing the intensity of the tone bursts, increases the amplitude and decreases the latency of the response. These findings illustrate the difficulty of establishing any fixed response criteria. Under optimum conditons, evoked potentials are obtainable to within 10 or 20 dB of most subject's subjective response threshold. Instructions or tasks which increase the subject's attention to the auditory stimuli increase both amplitude and latency. A third section describes a study of a large, negative potential that is present when the auditory stimulus is given information bearing properties. This wave was described, by Grey Walter, as a Contingent Negative Variation. This study was conducted with 40 institutionalized mentally retarded patients who presumably would have had some difficulty in forming the necessary association. The Contingent Negative Variation was present in 20 Mongoloids, but absent in 20 patients with unknown etiology. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 15, 1967
- Accession Number
- AD0660011
Entities
People
- Edgar L. Lowell