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Biomedical subjects

R L Gregory

Publications and source records attributed to R L Gregory.

At least 163 records · Page 9Linked to original sources
PubMed1978

Speech recognition with dynamic range reduction: (1) deaf and normal subjects in laboratory conditions.

Processing to reduce the dynamic range of speech should increase intelligibility and protect the impaired ear from overloading. There are theoretical and practical objections to using AGC devices to reduce dynamic range. These are overcome by using recently available signal processing employing high frequency carrier clipping. An increase in intelligibility of speech with this HFCC has been demonstrated, for normal subjects with simulated deafness, and for most partially hearing patients. Intelligibility is not improved for some patients; possibly due to their having learned to extract features which are lost. These patients may also benefit after training.

Acoustics↗
PubMed1977

Vision with isoluminant colour contrast: 1.A projection technique and observations.

An optical technique is described for projecting two-colour pictures with controlled brightness contrast, which may be set to zero-at isoluminance. Colour registration is maintained without adjustment or special setting up. It is suggested that colour-and brightness-contour registration in the visual channel is a problem which may be solved neurally be master brightness signals locking slave colour signals. The projection apparatus allows the supposed master brightness signals to be removed-at isoluminance-when contour disturbances should occur. Observation of this kind are reported.

Color Perception↗
PubMed1977

Role of intragastric pressure, pH, and pepsin in gastric ulceration in the rat.

A method of continuous gastric perfusion with "artificial gastric juice" was used in a study of individual factors (intragastric pressure, pH, and pepsin) known to participate in the pathogenesis of peptic ulcers. This method allowed change of only one factor at a time, while the other two remained constant. The gastric mucosa of normal rats, fasted for 48 hr, was found to be resistant to the ulcerogenic effects of artificial gastric juice perfused through the stomach for 6 hr without increasing the intragastric pressure. Perfusion of hydrochloric acid (pH 1.3) under increasing pressure produced ulceration of the corpus as well as forestomach portion of the stomach. The degree of gastric ulceration paralleled increases in intragastric pressure, acidity, and pepsin proteolytic activity. Inhibition of pepsin activity by a pepsin inhibitor protected the gastric mucosa even at the very low pH of 1.3. These results demonstrate that under the experimental conditions used, hydrochloric acid alone in the absence of pepsin does not produce ulceration of the rat stomach.

Animals↗