Seat-to-hand vibration transmissibility influence on cognitive performance via tablet evaluation

Abstract

Exposure to Whole Body Vibration can affect the individual’s cognition, and different frequencies and magnitude of vibration cause different effects, which can have either an improvement or deteriorate the individual’s cognitive abilities. The present work aims to correlate seat-to-hand vibration transmissibility with the cognitive performance, simulating the working condition of a bus fare collectors. For this purpose, tests with 20 volunteers on a vibrating platform with sinusoidal vibration applied in the vertical direction were performed. The vibration amplitudes of 0.2 and 0.7 m/s², and frequencies of 5 and 30 Hz were used. A daily routine of a bus fare collectors was simulated, based on data from the public transport system in the Belo Horizonte city. Vibration signals were collected on the platform chair and on the volunteer’s hands, and were post-processed. Cognitive performance was assessed using a Brain Training App, and three indicators were considered: score, accuracy and reaction time to respond. The results showed that the frequencies adopted were beneficial to the score and accuracy, with the frequency of 5 Hz having better results, and the reaction was negatively affected for both frequencies. The vibration transmissibility showed that both frequencies presented the characteristic of attenuation, that is, the vibration amplitudes decreases from the platform chair to the volunteer’s hands. Furthermore, there was a correlation (direct or inverse correlation) between the transmissibility with the reaction, accuracy and score when exposed to whole body vibration, and the type of correlation varied for each frequency and amplitude tested.