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Biomedical subjects

D L Weber

Publications and source records attributed to D L Weber.

31 records · Page 2Linked to original sources
PubMed1980

Detection of temporally uncertain signals.

The effects of signal uncertainty on detection performance were measured using a new procedure that allows precise specification of the initial temporal uncertainty. Five different models of the detection process, two assuming a continous representation of the sensory input and three assuming a discrete representation, were compared with the obtained data. The effects of varying signal uncertainty (the number of potential signal intervals was one, five, or ten) had little effect on detection performance. The one-parameter form of the choice model can be rejected without hesitation. The continuous Gaussian model and the symmetric two-state model are significantly different from the data. The high threshold and sophisticated two-state models provide accurate descriptions of the data that cannot be rejected on statistical grounds.

Acoustic Stimulation↗
PubMed1979

Suppression effects in backward and forward masking.

The differences in the suppression effect observed in forward and backward masking are consistent with an interpretation that suppression in forward masking results from a reduction of the effective level of the masker in the aditory periphery, and that the suppression in backward masking is influenced by these peripheral processes, but is dominated by additional, central processes. This conclusion is supported by experiments that show differences in the effect of ipsilateral versus contralateral presentation of the suppressor, and differences in the amount of the suppression observed as a function of the level, duration, and frequency of the suppressor.

Adult↗
PubMed1978

Suppression and critical bands in band-limiting experiments.

Band-limiting experiments were performed at three noise spectrum levels (N0 = 25, 40, and 55 dB SPL) for forward, simultaneous, and backward masking. Threshold for a 2-kHz sinusoid decreased for masker bandwidths greater than a "critical bandwidth" in nonsimultaneous masking. These results are evidence for a suppression effect not observed in simultaneous masking; however, a qualitative model of suppression can account for the results in all three types of masking. In addition, the data for simultaneous masking support Fletcher's [Rev. Mod. Phys. 12, 47--61 (1940)] rectangular filter interpretation of the band-limiting experiment and are well described by a level-dependent critical band.

Auditory Threshold↗
PubMed1978

Temporal factors and suppression effects in backward and forward masking.

We discuss several experiments examining the influence of temporal parameters on suppression effects in backward and forward masking. The signal is always a brief 10-ms 2-kHz sinusoid; the masker a narrow band of noise of 40-dB spectrum level, 200-Hz wide, centered at the signal frequency. In some conditions, the presence of a second band of noise of the same spectral level in the region of 2300--3700 Hz appears to suppress the effects of the masker. Changes in the amount of suppression are examined as functions of the delay and duration of the suppressor (experiments 1 and 2). Adding the suppressor during the 50-ms interval nearest the signal produces changes in the signal threshold that are similar to those produced by reducing the level of the masker during this interval for both backward and forward masking (experiment 4). The similarity of these results suggests the operation of peripheral processes common to both backward and forward masking. However, if one increases the duration of the suppressor beyond this 50-ms interval there is no effect on forward masking, but large additional reductions in backward masking. This difference, in conjunction with other recent experiments, suggests the operation of additional central processes in backward masking. For some observers, these additional processes appear to operate over fairly long periods of time (250-500 ms). Such long durations are inconsistent with the estimates of integration time (less than or equal to 200 ms) obtained for these same observers (experiment 3).

Adult↗
PubMed1977

Detection and recognition of pure tones in noise.

We examine the predictions of a new theorem relating signal identification (specifying a signal as a particular member of a set of potential signals) to signal detection (discriminating the presence of a signal). The theorem, derived in the context of signal-detection theory, requires that the signals be equally detectable and orthogonal. Our sinusoidal signals are partially masked by noise and their intensities adjusted to produce equal-signal detectability; we do not examine this assumption of the theorem. The theorem generally provides a reasonably accurate description of recognition performance for two-signal and four-signal conditions and is equally accurate for both the Yes-No and category-rating procedures. In a preliminary investigation of the orthogonality assumption, we varied the frequency separation between two signals. When the frequency separation between two signals is small (20 Hz near 1 kHz), the theorem fails to provide a good description of performance.

Humans↗
PubMedDate not supplied

Traumatic lesions of the metatarsophalangeal joint of the great toe in athletes.

In the 1972, 1973, and 1974 football seasons at the University of Arkansas, 74 players sustained sprains of the ankle, producing a total of 152 missed practices and 6 missed games. Although only 18 injuries of the first metatarsophalangeal joint complex were seen, these later resulted in 92 missed practices and 7 missed games. This injury has been a significant problem for both the university and for most other major institutions, judging from a 70% response to 94 questionnaires sent to trainers of 94 large colleges and universities throughout the United States. It is the researchers opinion that the artificial turf surface, particularly as it ages, the shoes, and shoe fitting are all possible contributors to the incidence of the problem. Nonoperative treatment, whose hallmark is rest, is the treatment of first choice. Taping and splinting with a 0.51-mm spring steel splint with reinforcement, both pre- and postinjury, are beneficial. Injections of steroids or any other attempt to return the still painful athlete to activity are contraindicated. Late surgery, particularly in the event of capsular ruptures, as well as early repair, can be of benefit. The need to re-evaluate the shoes and playing surfaces in the light of this and other injuries is emphasized.

Athletic Injuries↗