Are on board comfort classes noise and vibration levels really suitable?

Abstract

In shipbuilding industry, comfort is a relevant issue both for crew members and passengers. A comfortable environment enables crew members to perform accurately their tasks and it is an effective factor contributing to the satisfaction of passengers. Noise and vibration, as environmental parameters, play an important role in subjects' comfort. Naval Classification Societies established series of noise/vibration comfort level criteria, which, however, did not take into account some aspects: 1) noise/vibration recordings are carried out during time periods shorter than the exposure time of passengers; 2) the subjective mood is not investigated. In the present study, we studied comfort perception by measuring heart rate variability and mood. We exposed participants to four levels of acoustic noise [from 45 to 55 dB(A)] and three levels of vibration (1.5, 1.8, 2 mm/s) inside a full-scale mock-up of a cruise ship cabin. We found that the increase of noise/vibration intensity determines an increase of heart rate variability and negative mood. However, changes in comfort responses did not occur for the noise/vibration comfort thresholds identified by the Classification Societies. Our results evidence the importance to include psychophysiological measure of comfort when defining comfort criteria on board.