Noise in heavy goods vehicles

Data are given of noise spectra obtained in the cabs of new, and in-service, heavy goods vehicles having gross vehicle weights up to 40 tons. Comparisons are made between dB(A) and linear sound pressure levels under motorway conditions at 30, 40 and 50 mile/h.The emphasis has been on the collection of data, particularly in the infrasonic region, which lies in the octave bands between 2–20 Hz. The results confirm that high levels of infrasound exist in the cabs and these levels are, possibly, influenced by the ventilation of the cab and the road speed.The data obtained are discussed from the points of view of hearing hazard, impaired vigilance, and possible dangers arising from infrasound. It is concluded that in the noisier vehicles there is certainly a danger to hearing, and from available data on the effects of noise in the laboratory and in industry, there is probably some effect on vigilance. The extent of the possible hazard of infrasound is less well established and a need for further research is pointed out.