Infrasound: Incidence and significance in motor cars

Abstract

During the last two decades there has been much interest in the effects of infrasound on people. This is partly due to claims made by some scientists that infrasound could cause effects such as intestinal irritations, throbbing in the head, nervous breakdowns, certain allergies, and other unpleasant phenomena of modern life found in industrial cities. Early work [J. E. Green and F. Dunn, J. Acoust. Soc. Am. 44, 144–145 (1968)] concluded a positive correlation between infrasonic thunderstorms and road accidents and other deviant behavior. Others have addressed the question “Does infrasound make drivers drunk?!” With the possible effects on road safety this paper aims to assess the incidence of infrasonics in transport environments with particular reference to European passenger cars. It was found that infrasonic sound pressure levels (ISPL) were proportional to vehicle speed, window opening, and vehicle size. Also driving with a fitted roof rack tended to increase ISPL by as much as 20 dB. It was also found that under most adverse driving conditions ISPL never exceeded 110 dB which is below human performance thresholds. It seems therefore that the original significance placed on the incidence of infrasound in cars was misplaced. Also it is concluded that further work needs to be done to establish the effects of exposure duration on human performance thresholds and to include the higher low frequencies as well. [Fundamental research project conducted by S. D.Haddad and Charles Marks at Loughborough University, England in 1980 with further investigations by S. D. Haddad concluded in 1983.]