Brüel & Kjær Sound & Vibration Measurement A/S - HANDBOOK
    (May be copied and distributed - the source must be stated and acknowledged to be B&K)

WHO Guidelines for Community Noise
    (Edited by Birgitta Berglund, Thomas Lindvall, Dietrich H Schwela)
Adverse health effects of noise : Sources with low-frequency components. Disturbances may occur even though the sound pressure level during exposure is below 30 dBA. The evidence on low-frequency noise is sufficiently strong to warrant immediate concern. Various industrial sources emit continuous low-frequency noise (compressors, pumps, diesel engines, fans, public works); and large aircraft, heavy-duty vehicles and railway traffic produce intermittent low-frequency noise. Low-frequency noise may also produce vibrations and rattles as secondary effects. Health effects due to low-frequency components in noise are estimated to be more severe than for community noises in general (Berglund et al. 1996). Since A-weighting underestimates the sound pressure level of noise with low-frequency components, a better assessment of health effects would be to use C-weighting. When prominent low-frequency components are present, measures based on A-weighting are inappropriate. However, the difference between dBC (or dBlin) and dBA will give crude information about the presence of low-frequency components in noise. If the difference is more than 10 dB, it is recommended that a frequency analysis of the noise be performed. See WHO - Guideline Values: Section 4.3 Specific Environments - Chapter 4. In residential populations heavy noise pollution will most certainly be associated with a combination of health effects. For example, cardiovascular disease, annoyance, speech interference at work and at home, and sleep disturbance. Therefore, it is important that the total adverse health load over 24 hours be considered and that the precautionary principle for sustainable development is applied in the management of health effects. See WHO - Guideline: Adverse health effects of noise - Chapter 3.

Low frequency noise and stress: Stresses may be grouped into three broad types: cataclysmic stress, personal stress and background stress. Cataclysmic stress includes widespread and devastating physical events. Personal stress includes bereavements and similar personal tragedies. Cataclysmic and personal stresses are evident occurrences, which are met with sympathy and support, whilst their impacts normally reduce with time. Background stresses are persistent events, which may become routine elements of our life. Constant low frequency noise has been classified as a background stressor (Benton, 1997b; Benton and Leventhall, 1994). Whilst it is acceptable, under the effects of cataclysmic and personal stress, to withdraw from coping with normal daily demands, this is not permitted for low level background stresses. Inadequate reserves of coping ability then leads to the development of stress symptoms. In this way, chronic psychophysiological damage may result from long-term exposure to low-level low frequency noise. Changes in behaviour also follow from long-term exposure to low frequency noise. Those exposed may adopt protective strategies, such as sleeping in their garage if the noise is less disturbing there. Or they may sleep elsewhere, returning to their own homes only during the day. Others tense into the noise and, over time, may undergo character changes, particularly in relation to social orientation, consistent with their failure to recruit support and consent that they do have a genuine noise problem. Their families and the investigating EHO may also become part of their problem. The claim that their "lives have been ruined" by the noise is not an exaggeration, although their reaction to the noise might have been modifiable at an earlier stage. See section 10 of Report for Defra by Dr Geoff Leventhall: A Review of Published Research on Low Frequency Noise and its Effects (PDF file).

Noise annoyance from wind turbines - a review (PDF file)
    (Annoyance caused by diesel trains decreases when the modulation depth was reduced)

Low Frequency Noise - Technical Research Support for DEFRA Noise Programme (PDF file)
    (Extracts of this publication may be made for non-commercial in-house use, subject to the source being acknowledged)

A Review of Published Research on Low Frequency Noise and its Effects (PDF file)
    (Report for Defra by Dr Geoff Leventhall Assisted by Dr Peter Pelmear and Dr Stephen Benton)
The above publication (excluding the logo) may be reproduced free of charge in any format or medium provided that it is reproduced accurately and not used in a misleading context. The material must be acknowledged as Crown copyright with the title and source of the publication specified.

Note: Low frequency noise causes extreme distress to a number of people who are sensitive to its effects. Such sensitivity may be a result of heightened sensory response within the whole or part of the auditory range or may be acquired. The noise levels are often low, occurring in the region of the hearing threshold, where there are considerable individual differences. There is still much to be done to gain a fuller understanding of low level, low frequency noise, its effects, assessment and management. Survey papers of low frequency noise and its occurrence include (Backteman et al., 1983a; Backteman et al., 1983b; Backteman et al., 1984a; Backteman et al., 1984b; Berglund et al., 1996; Broner, 1978a; Hood and Leventhall, 1971).

Example of the Impact of Modulation: At the highest modulation depth at 2.0Hz modulation frequency, the level was reduced by 12.9dB averaged over the subjects. This work confirms the importance of fluctuations as a contributor to annoyance and the limitation of those assessment methods, which do not include fluctuations in the assessment. (See: Report for Defra by Dr Geoff Leventhall Assisted by Dr Peter Pelmear and Dr Stephen Benton)

    (Impact of Low Frequency atmospheric noise on humans)

LF Noise annoyance - Wind Turbine Disaster: LOTTA NILSSON
    (There is no mercy for people crying for help)

Low Frequency Noise, Vibration and Active Control
    (low frequency noise and vibration and their powerful effects on man, animals and the environment)

    (NOISE TAS is a Tasmanian organisation dedicated to the elimination of unwanted noise)

Southern African Acoustics Institute. (SAAI)
    (Acoustics in Southern Africa - SAAI provides a forum for all aspects of acoustics)

    (Not for publication - please use these pages for comment and correction purposes only)