Sound propagation of reverse alarms used on heavy vehicles


  • C. Laroche Sonometric Inc., Montreal, Que., Canada
  • M.-J. Ross Sonometric Inc., Montreal, Que., Canada
  • L. Lefebvre Sonometric Inc., Montreal, Que., Canada
  • R. Laraocque Sonometric Inc., Montreal, Que., Canada
  • R. Hetu
  • A. L'Esperance


acoustic applications, acoustic wave propagation, aeroacoustics, alarm systems, safety, reverse alarms, heavy vehicles, acoustical characteristics, sound pressure level, 700 to 2800 Hz


In Quebec, the regulation related to the use of reverse alarms on heavy vehicles referred to the SAE J994 Standard. Regarding acoustical characteristics, this standard states that the predominant sound frequency of the alarm should fall within the frequency range of 700-2800 Hz. The cycles of sound pulsations from the alarm shall be of the order of 1-2/sec. The duration of the `on' and `off' intervals shall be approximately equal in length. The alarm should be tested in free field, 4 feet above a horizontal reflecting plane or laboratory equivalent, with the microphone 4 feet from the alarm's horn along its 0 degree axis. The alarm in then classified according to its sound pressure level: Type A: 112 dBA, Type B: 107 dBA, Type C: 97 dBA, Type D: 87 dBA and Type E: 77 dBA. The accidents reported above raise the question as to what extent such a standard insures that every worker will perceive the alarm at any position behind the heavy vehicle

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How to Cite

Laroche C, Ross M-J, Lefebvre L, Laraocque R, Hetu R, L’Esperance A. Sound propagation of reverse alarms used on heavy vehicles. Canadian Acoustics [Internet]. 1993 Sep. 1 [cited 2024 May 26];21(3):29-30. Available from:



Proceedings of the Acoustics Week in Canada

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