Environmental low frequency noise is a growing cause of annoyance and a potential hazard to health for many people.
Adverse effects of low frequency noise and vibration on humans may include permanent or temporary hearing loss, aural pain, loss of balance, effects on the respiratory system, annoyance, cardiovascular and endocrine effects, decreased performance and cognition, sleep disturbance, effects on communication, psychosocial and mental health effects.
The primary effect due to low frequency noise appears to be annoyance. Annoyance levels are particularly high in cases where masking effects due to other source of background noise such as traffic are low. Complainants therefore often dwell in otherwise quiet rural or suburban areas.
There is often an apparent contradiction in low frequency noise cases between individuals claiming to be suffering unbearable noise exposure and the inability of others to perceive any low frequency sound at all. This may be explained by the fact that contours of equal loudness of sound are very tightly spaced at low frequencies, so that for an individual, a slight increase in sound level of low frequency noise can cause a large increase in subjective loudness level. In addition, inter-individual sensitivity variations may be such that low frequency noise at a particular level may be inaudible for one person, but relatively loud for the next. Sensitivity to low frequency noise also appears in some individuals to build up over time.
The number of industrial noise sources capable of creating low frequency noise is increasing, as plant and equipment size become larger. However, neither British nor International standards dealing specifically with low frequency noise problems exist as of yet.
This paper details a case study that illustrates the urgent need for improved diagnosis of low frequency noise problems. In order to enhance the prospects of successful diagnosis, a novel measurement methodology was used and assessment was made against objective criteria from a German national standard.