Graduate Student: Olivia Heui Young Park, Ph.D. Student, Graduate Program in Acoustics
The effects of transportation noise (specifically rail noise) on cognitive function were investigated using an electroencephalography (EEG) headset, an electrocardiogram (ECG), and an electrodermal activity (EDA) device with two cognitive tasks, digit span and mental arithmetic. Recorded rail noise were obtained and were reproduced in a spatially accurate manner in the AURAS facility, to recreate rail noise coming through an open window in an office at two levels, 50 dBA and 70 dBA.
EEG signals can be analyzed as five frequency bands: delta (0.5 – 4 Hz), theta (4 – 8 Hz), alpha (8 – 12 Hz), beta (12 – 25 Hz), and gamma (25 Hz+). Each frequency band corresponds to different activity and excitations in different parts of the brain. The frontal theta to parietal alpha ratio (task load index, TLI) is often used for measuring cognitive load, as the alpha band decreases while the theta band increases with increasing work load.
EMOTIV EPOC x EEG headset (source: EMOTIV)
Heart rate variability (HRV) measured with the ECG and skin resistance measured with the EDA are metrics for stress and arousal, and are often used as indicators for changes in cognitive load. The HRV is calculated with the root mean square of successive differences between normal heartbeats (RMSSD) for successive R-R peaks.
Cognitive function can be divided into several sub functions, such as attention, perception, and memory. After series of piloting, the 7-digit digit span task and 3-digit addition mental arithmetic tasks were chosen. To reduce learning effects, three training sets were given to participants for each task.
A NASA-TLX (task load index) based, 15-question subjective questionnaire was given after each acoustic condition.
A repeated-measures MANCOVA was conducted to evaluate the effects of the acoustic condition on performance and physiology, and the acoustic condition was statistically significant. The order of rail noise, gender, age and other covariates were not statistically significant. A separate repeated-measures MANCOVA was conducted for the subjective ratings, and the acoustic condition, gender, and noise sensitivity index were statistically significant.
Project Publications/Presentations:
- Park, HY*, Vigeant, M.C., and Dittberner, A (2023). “Assessing cognitive effects of transportation noise on office workers with physiology and task performance” J. Acoust. Soc. Am. 153, A23
- Park, HY*, Vigeant, M.C., and Dittberner, A (2022). “Assessing cognitive effects of transportation noise on office workers with electroencephalography and performance” J. Acoust. Soc. Am. 152, A210 [1st place]
- Park, HY*, Vigeant, M.C., and Dittberner, A (2022). “Assessing cognitive effects of transportation noise on office workers with performance tasks and physiological data” CAV (Center for Acoustics and Vibrations) [Poster Winner]