Dawson, H. Practical Aspects of the Low Frequency Noise Problem
H. Dawson, Rolls-Royce, Bristol, U.K.
Journal of Low Frequency Noise and Vibration, vol. 1, no. 1, 1982
…. very often, and certainly much more frequently than is currently recognised, the levels of low frequency noise are enough to interfere with people to a degree sufficient to cause significant misery, distress and economic penalty.
This paper describes some practical aspects of both the historical and current low frequency noise problem, proposes techniques for its specification and control, outlines some silencing methods and suggests an action plan for those interested in the subject.
Definitions: The Low Frequency sound referred to in this paper is arbitrarily confined to frequencies beiow 261 Hz. The term Infrasonic refers to frequencies below the generally accepted lower limit of auditory perception of 20 Hz, although it is known that infrasound, while losing its tonal quality at frequencies below 16 Hz is in fact audible, given sufficient intensity, down to 1 Hz.
Low Frequency Sound: Low frequency sound is omnipresent and although our ears do not readily detect it, the noise spectrum measured in even the quietest location is dominated by energy at the low end of the spectrum (Fig, 1).
However, very often, and certainly much more frequently than is currently recognised, the levels of low frequency noise are enough to interfere with people to a degree sufficient to cause significant misery, distress and economic penalty.
… In a given population exposed to a sufficient level of low frequency noise some people can be distressed to an extreme degree while others remain quite unaffected. Once a complaint-inducing level has been reached, there is no correlation between absolute sound pressure level and the number of complaints from a given population – people either complain or they do not. …
Once a person has displayed some sensitivity to low frequency noise, further exposure lowers the sensitivity threshold. Any sensitivity is exacerbated by the presence of other stresses. The low frequency sensitivity syndrome includes: feelings or irritation/unease/stress/undue fatigue; headache; nausea; vomiting; heart palpitations; disorientation; swooning/prostration.