The paper reviews perception of low frequency noise (LFN) and the responses of people to LFN. Sometimes, when there are complaints of LFN and its effects, a specific noise cannot be measured. The possibilities are considered for development of enhanced sensitivity, for alternative (non-aural) receptors at very low frequencies and for false perceptions. The way in which we measure LFN may contribute to the problems. LOW FREQUENCY NOISE AND INFRASOUND Low frequency noise is typically the range 10

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... Hz to 100Hz, although it can be extended an octave at each end of this to give 5Hz to 200Hz. This wider range includes much of what is called "infrasound". There is some confusion over the meaning of the term "infrasound". A popular interpretation is that it is sound of such low frequency that it is below the lower frequency limit of hearing, generally taken to be around 20Hz. A definition of infrasound, found in Standards, is: Acoustic oscillations whose frequency is below the low frequency limit of audible sound (about 16Hz). (IEC,1994) However, sound at frequencies below 16Hz is clearly audible if the level is high. The hearing threshold has been measured reliably down to 4Hz for listening in an