Three experiments were conducted to determine whether variations in the perceived distance to a test sound could influence its loudness in the absence of physical changes in sound-level. The phenomenon of visual capture provided the means for manipulating apparent distance. A 'dummy' loudspeaker was used to vary the apparent source location of a short noise stimulus while the true source of this sound remained fixed (and hidden) with respect to the observer. Sound-levels from 40 to 75 dB(A) were presented to independent groups of observers in either anechoic or semi-reverberant acoustical environments. In general, reported loudness increased with perceived distance. This finding has implications for conceptualizing the phenomenon of loudness constancy.
Time‐of‐day variations were studied both in tonic accomodation and in tonic vergence. Thirty‐six male volunteers were measured once in the morning and at one other time on the same day. The mean baseline value of tonic accomodation was 2.02 D. Time‐of‐day variations were found, with a late evening measure being + 0.6 D greater than the morning value. No independent time‐of‐day fluctuations were found in tonic vergence. Post‐hoc analysis, however, showed that tonic vergence tended to shift in the same direction as an individual's tonic accommodation during the afternoon. During the evening, tonic vergences tended to shift oppositely to tonic accommodation.
The purpose of these projects was to design new and safe commode-shower wheelchairs for use by individuals with spinal cord injuries and caregivers. The need for new chairs resulted from the many safety problems associated with existing models such as inability to fold, patient falls while transferring, development of pressure sores. An iterative process of design, prototype fabrication and clinical evaluation was used to develop both a rigid and a folding shower-commode wheelchair. During this process, new wheelchair features were invented and patented. The shower-commode wheelchairs were successfully evaluated with patients having spinal cord injuries and their caregivers at VA Medical Centers. Questionnaires were developed to assess the chair's features and function. The evaluation results led to the conclusion that the new Shower-Commode Wheelchairs solved all the safety and usability problems found in existing models.
A survey of Paraplegia News readers was conducted to examine several issues related to the use of bathroom fixtures by disabled people. Responses indicated a wide range of preferences or dislikes depending on the txpe of disabilities of readers. This survey led to the conclusion that bathroom fixtures are far from meeting the functional needs of a sizable portion of the population.
Practical methods and procedures which decrease the amount of time required to conduct an evaluation can be invaluable to human factors specialists as most are usually limited by economic and time constraints. Presented are the hypotheses that 1) the amount of effort required to collect survey data using checklist procedures is related to the quantities of controls and displays and is relatively independent of the system's operational complexities, and 2) the amount of effort required to conduct task analyses is related to the number of operators involved and the number of different ways in which operators interface with equipment, and is relatively independent of control and display quantities once these quantities reach a certain level. Procedures for collecting large quantities of data using checklists are described and the results of applying these procedures in a nuclear power plant control room where control board components exceeded 4000 instruments are discussed. The procedures used involved; 1) the development of a photographic mock-up of the control board, 2) serial numbering all components, 3) preparing component record sheets and discrepancy report forms prior to the evaluation, 4) modifying traditional checklists to a new format, and 5) revising the data collection methods for checklists.
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