Observations placeholder

The Environmental Protection Agency – UK

Noise has been defined as unwanted sound. We are all aware of the noises that surround us in our everyday lives, many of which are a source of nuisance. The effect of low frequency noise (LFN), however, is often not recognised as a nuisance, even though it may have a profound effect on the psychological and physiological well being of some people.

…..LFN can be more noticeable indoors, which is why it is often associated with disturbed sleep. In the open air other noises such as traffic may mask the annoying low frequencies. Indoors, middle and high frequency noise from outside is reduced because the insulating effect of the building increases with sound frequency. Noises from the lower frequency bands, however, may remain the same, or even increase - hence rattling windows etc. Another problem is that LFN travels further than higher frequencies, so the source is often difficult to trace.

Effects of Low Frequency Noise

A low frequency noise is very often characterised by a hum or rumble. It may be confused with tinnitus (ringing/hissing in the ears with no obvious cause).

Health

The hearing sensitivity range of people varies; therefore people who are disturbed by LFN may feel isolated if no one else is annoyed by the noise. Symptoms of LFN annoyance are those associated with stress. These include feelings of irritation and unease, psychological problems, fatigue, headache, nausea and disturbed sleep.

It is not clear at what level Low Frequency Noise may be physically damaging; however, the unpleasant symptoms it can induce are sufficient to cause disruption and significant social and economic penalties to sufferers. A review of research into low frequency noise is available in PDF format from the Defra website

Nuisance

How far low frequency noise presents a serious nuisance problem is uncertain, but it is often a source of irritation. Assessing the level of nuisance caused by low frequency noise is difficult. Ordinary sound level meters may not be able to detect LFN on the decibel scale as its decibel level is often lower than background noise. A narrow band frequency analyser is required to measure it. Noise nuisance is determined by the magnitude of the noise on the decibel scale. In the case of LFN this scale is not appropriate so it is often difficult to prove a nuisance.

Hums

Throughout the country there are cases of people who can hear 'hums'. These sounds have no obvious source. In some areas small groups of people apparently complain about noise from the same, unidentified source. These have been blamed on industrial sources and on gas pipelines.