Environmental noise in community living

• Prolonged or excessive exposure to noise, whether in the community or at work, can cause permanent medical conditions, such as hypertension and ischemic heart disease. (ref. WHO Guidelines p.XII)
• Noise can adversely affect performance, for example in reading, attentiveness, problem solving and memory. Deficits in performance can lead to accidents. (ref. WHO Guidelines p.XII)
• Noise above 80 dB may increase aggressive behavior. (ref. WHO Guidelines p.XIII)
• A link between community noise and mental health problems is suggested by the demand for tranquillizers and sleeping pills, the incidence of psychiatric symptoms and the number of admissions to mental hospitals. (ref. WHO Guidelines p.XII)

The document critically reviews the adverse effects of community noise, including interference with communication, noise-induced hearing loss, annoyance responses, and effects on sleep, the cardiovascular and psycho physiological systems, performance, productivity, and social behavior. Noise measures or indices based only on energy summation are not enough for the characterization of most noise environments. This is particularly true when concerned with health assessment and predictions. It is equally important to measure and display the maximum values of the noise fluctuations, preferably combined with a measure of the number of noise events, and to assess whether the noise includes a large proportion of low frequency components.

For dwellings, recommended guideline values inside bedrooms are 30 dB LAeq for steady-state continuous noise and for a noise event 45 dB LAmax. To protect the majority of people from being seriously annoyed during the daytime, the sound pressure level from steady, continuous noise on balconies, terraces, and in outdoor living areas should not exceed 55 dB LAeq. To protect the majority of people from being moderately annoyed during the daytime, the sound pressure level should not exceed 50 dB LAeq. At nighttime outdoors, sound pressure levels should not exceed 45 dB LAeq, so that people may sleep with bedroom windows open.

In schools and preschools, to be able to hear and understand spoken messages in class rooms, the sound pressure level should not exceed 35 dB LAeq during teaching sessions. For hearing impaired children, a still lower level may be needed. The reverberation time in the class room should be about 0.6 s, and preferably lower for hearing impaired children. For assembly halls and cafeterias in school buildings, the reverberation time should be less than 1 s. For outdoor playgrounds the sound pressure level from external sources should not exceed 55 dB LAeq.

In hospitals during nighttime, the recommended guideline values for wardrooms should be 30dB LAeq together with 40 dB LAmax. Since patients have less ability to cope with stress, the equivalent sound pressure level should not exceed 35 dB LAeq in most rooms in which patients are being treated, observed or resting.

The concern for protecting young people's hearing during leisure time activities warrants provisional guidelines for concert halls, outdoor concerts and discotheques. It is recommended that patrons should not be exposed to sound pressure levels greater than 100 dB LAeq during a 4-hour period. The same guideline values apply for sounds played back in headphones when converted to equivalent free-field level. To avoid hearing deficits from toys and fireworks, performers and audience should not be exposed to more than 140 dB (peak) of impulsive sounds. Existing large, quiet outdoor areas in parkland and conservation areas should be preserved and the background-to-noise ratio be kept low.