Mary Anne Baker

Noise stress and circadian arousal in self-paced computation

Previous work(Frankenhaeuser & Lundberg, 1977) has shown that unpaced mental arithmetic is performed at slower rates in noise, despite unchanged catecholamine indices of arousal; only male subjects were used, tested early in the day. Since the times of testing entail arousal effects that interact with noise stress, and the sex of subject further modifies these interactions, a new experiment was designed to include these variables. Men and women were tested on the Norinder mental arithmetic task, in quiet or in noise, either in the morning, when arousal was low, or during the early evening, when temperature curves indicate that arousal should be high. Analysis of the number of problems attempted shows a significant drop for men in noise in the morning, but an interaction due to reversal of the noise effect in the evening; there is no main effect of noise when womens scores are included. The results are compatible with interpretations combining motivation and cognition, and they demonstrate the importance of the experimental variables in explaining noise stress effects.

Noise, sex and time of day effects in a mathematics task.

Abstract A pilot experiment explored the effects of list length (four, six or eight digits) and presentation rate (1-6.5 per second) in a task of computer-paced addition. As the experimental variables changed, men tended to vary their speed of response while women tended to vary their level of accuracy. Conditions selected from the first experiment (six digits at two and four per second) were employed in a second, with the object of examining interactions among noise, time of day and sex. Practice effects over three sessions of testing confirmed the sex difference in speed-accuracy strategies. Male and female performance tended to change between the a.m. and p.m. test periods, such that women in quiet behaved similarly to men in noise, showing poorer p.m. performance in terms of response times and non-responses, but fewer commissive errors. Although the effects of circadian arousal were varied, noise consistently produced an effect different from that of time of day. A complex model, supported by more fac...

Implications of measurement of eye fixations for a psychophysics of form perception

It was suggested that insights into feature analysis of processes involved in form identification might be gained from an analysis of eye movements made by Ss as they identified patterns. Fixations were measured during identifications of histoforms, polygons, and Vargus 10 figures. Eye fixations were measured, and Ss rated sections of the figures in terms of their importance. Eye fixations were measured in terms of number of changes and duration of fixations. The number of changes in fixation were found to reflect only individual differences. Duration of fixation was found to vary significantly with location within figures, with fixations being longest where changes of contour occurred. There was also a tendency to look longer at the top of polygons and Vargus 10 figures and at the center of histoforms. Ratings of importance were highest for sections of figures fixated for longer duration-generally areas in which changes of contour were present.

Effects and aftereffects of continuous noise and computation work on risk and effort choices

Choices between risk and effort, in a format (COPE) previously shown to reflect fatigue, were obtained from subjects in noise or quiet. Both sexes were used in the experiment, half the subjects working at the Norinder arithmetic task while half rested. The COPE test took a computational form, offering choices between digit lists of differing lengths in which target sums were imbedded. The baseline choice levels were established in quiet, but half the subjects were exposed to noise during the posttest. As previously found in comparable conditions, the Norinder task showed no effect of noise. Pretest-posttest comparisons on the COPE test showed that exposure to noise, like computation work, had the predicted effect of decreasing the choice of high-probability, high-effort alternatives. The presence of noise during posttest had no overall effect on risk effort choices, although there were indications that changes of any kind in the test conditions might be a factor. The data seem difficult to explain in an arousal framework, but may be simply interpreted as showing that exposure to noise produces real fatigue.

WOMEN'S REACTIONS TO REPRODUCTIVE PROBLEMS

In this study of reproductive problems and womens reactions to them, 30% reported an unplanned pregnancy, 13% had infertility problems, 4% had an abortion, 18% had a miscarriage, 5% experienced infant death, 18% had difficult pregnancies or delivery, 15% had a tubal ligation, and 15% had an hysterectomy. There were marked psychological responses of depression and increased stress which improved as the women learned more about the problem and drew closer to their families and others with similar problems.

Neural‐network‐based voice‐tracking algorithm

A voice‐tracking algorithm was developed and tested for the purposes of electronically separating the voice signals of simultaneous talkers. Many individuals suffer from hearing disorders that often inhibit their ability to focus on a single speaker in a multiple speaker environment (the cocktail party effect). Digital hearing aid technology makes it possible to implement complex algorithms for speech processing in both the time and frequency domains. In this work, an average magnitude difference function (AMDF) was performed on mixed voice signals in order to determine the fundamental frequencies present in the signals. A time prediction neural network was trained to recognize normal human voice inflection patterns, including rising, falling, rising–falling, and falling–rising patterns. The neural network was designed to track the fundamental frequency of a single talker based on the training procedure. The output of the neural network can be used to design an active filter for speaker segregation. Tests...

Coordinated use of FEM/BEM and SEA for the acoustic response of Delta II RL 10B-2 deployable nozzle

The coordinated use of statistical energy analysis (SEA) and detailed finite element (FEM) and boundary element (BEM) analysis provided an effective design tool for assessing the impact of acoustic loading on the RL10B-2 deployable nozzle. SEA provided an early assessment of the impact on the design, the critical areas of the cone, the relative importance of radiation damping and added damping, and the frequency range to be addressed. The acoustic structural analysis with FEM/BEM analysis provided a detailed picture of stress distributions for design insight, load combinations, and margin of safety determinations for spacecraft qualification. The combined tools allowed the project to deal with the midfrequency range so important to many spacecraft and often beyond the range of either approach alone.

Design of damping treatment for the Delta III RL 10B-2 deployable nozzle

In the development of the RL10B-2 propulsion system, analysis to address sine and acoustic loads identified the need to predict, design, and verify damping levels. Early design efforts indicated the need to increase the damping levels to ensure positive margins. Modal testing was used to determine material damping in samples and to assess the effectiveness of adding damping material. Analytical studies were used to select damping materials and predict the incremental damping available from candidate damping materials. These analytical studies demonstrated a large difference in damping from bending and membrane deformation and the need to determine how these different types of deformation participated in various modes. Numerical methods using nozzle finite element models were developed to more accurately assess mode-bymode damping. Final damping assessment was done by modal testing of entire nozzle.

Comparison of BEM and FEM for computation of acoustic resonant response in a laser chamber

For lasers used in the computer chip etching process, laser performance, as measured by uniformity in the energy output for etching, is affected by the density of the chamber gas at the laser electrode. The laser produces longitudinal shock waves that propagate transverse acoustic pulses. Acoustic modes of the gas within the laser chamber respond to these pulses and can create a resonant response resulting in a very nonuniform energy output of the laser. These phenomena have been studied using finite‐element (FEM) and boundary‐element (BEM) methods to model the laser chamber and to predict the forced response. The effectiveness of these two approaches is compared. Accuracy, computing efficiency, and ease of modeling have been considered. The challenge that is addressed is the representation of the internal structure within the chamber. The baffling effects of the internal structure provide the means to shape the response either exaggerating or attenuating the resonance. BEM and FEM methods are explored as design tools to predict the response and achieve the desired uniformity of pressure and density.

Age‐related hearing loss, temporary threshold shift and permanent threshold shift in four strains of mice.

A total of 96 mice from two inbred and two hybrid strains were tested for TTS (temporary threshold shift) and PTS (permanent threshold shift) using electrophysiological procedures for auditory brain‐stem responses. Testing continued for up to 3 months following 2 h of exposure to 110‐dB broadband noise. The inbred and hybrid strains carrying genes for age‐related hearing loss showed TTS almost equal to their PTS ‘‘thus anticipating their tendency to hearing loss.‘‘ On the other hand, the inbred and hybrid strains not carrying those genes showed considerable recovery from their original TTS losses. Those with age‐related hearing genes were very susceptible to noise‐induced PTS. An additional effect was the presence of strong correlations between TTS and PTS for both inbred strains, but no correlation for the two hybrid strains. Noise exposure history plays a role in the noncorrelations between TTS and PTS typically found in humans. Could genes influence correlation between TTS and PTS in humans?