An Index for Motor Vehicle Passengers Acoustical Comfort

Usually only noise equivalent levels are employed to individuate acoustical comfort for motor vehicle passengers. However, noise levels do not take into account many other phenomena which may contribute to acoustical comfort such as insulation, speech intelligibility, engine noise hearing expectance and so on. An original vehicle comfort index (VCI) is here proposed which is obtained by a peculiar procedure: physical parameters (PP) such as noise equivalent level, statistical levels, STI index and vehicle acoustic insulation have been measured for different vehicles at several velocities. An arbitrary VCI scale has been introduced. VCI values for different comfort conditions have been determined by a jury test. Jury test has been led by adopting a S.A.O. (Statistical Average Observer) which was asked to judge vehicle acoustical comfort in terms of the proposed VCI scale. A relation between jury test results (experimental VCI) and PP has been introduced; thus, VCI may be evaluated by means of a measurement campaign for any condition.