The study was aimed to investigate main effects and interaction effects of intermittent noise and random vibration in short-term memory scanning ability. Two level factorial study (23) with 3 factors to be investigated i.e. intermittent pink noise (56-76 dBA and 65-85 dBA), vibration in Z direction (with and without) and vibration in X direction (with and without) were applied. Usage of this design enabled observation of main effect and interaction effect among factors being investigated. Since noise was intermittent, higher level of noise was presented as burst of random duration i.e. 1 to 9 sec interrupted with random duration periods of lower level of noise i.e. 1 to 3 sec. Gaussian random vibrations ranged from 2- 10 Hz with magnitude of 0.15 m/s2 (r.m.s.). A control experimental condition was also added as the baseline for reaction time performance. Twelve healthy male convenient subjects were involved in performing short term memory scanning task (Sternberg task) while they were exposed in nine different experiment conditions. Task performance (reaction time of correct answers and accuracy) and subjective assessment data (ratings of subjective annoyance and NASA-RTLX) were collected during the experiment. Positive correlation was revealed on correlation between reaction time and subjective assessment while negative correlation was revealed between accuracy and subjective assessment however no significances were found on main and interaction effect of noise and vibration. Nonetheless, as subjects division applied, based on their sensitivity to environmental stressors i.e. high sensitivity group (group 1) and low sensitivity group (group 2), significant detrimental effect of noise on accuracy were demonstrated (group 1, p<0.05; group 2, p<0.05). However, both groups performance only differed in terms of reaction time in negative probes (p<0.1) even though group 1 tended to perceive environmental conditions as more annoying and task workload as harder compared to group 2.
Author: Hermawati, Setia
Source: Luleå University of Technology
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