Community Impacts of Noise Engineering Flashcards
The reaction of individuals to a sound/noise depends on
- Time of day,
- nature of the source,
- individual noise sensitivity,
- activity (concentrating, sleeping, socialising),
- sense of control over the noise source,
- your perception of the noise (familiarity, memories),
- age, level of hearing
Annoyance
Annoyance in populations exposed to environmental noise varies not only with the acoustical characteristics of the noise but also with many non-acoustical factors that are social, physiological, or economic in nature.
Impacts of environmental noise
Annoyance, sleep disturbance, speech/communication interference, physiological functions, mental illness, performance
In terms of noise annoyance, special attention should be given to
Noise sources in an environment with a low background noise level e.g. Night traffic (deliveries) in suburban residential areas.
Environments where a combination of noise and vibrations are produced e.g. Heavy veichles on highways
Sources with low frequency components e.g. Disturbances may occur even though the sound pressure level during exposure is below 30 dBA
Primary effects of noise On sleep
Delayed sleep onset, awakenings, alterations in sleep stages and the depth of sleep stages.
Secondary effect of noise on sleep
Increased fatigue, depressed mood or well being, decreased performance, increased risk of accidents
Sound pressure and sound levels for a good sleep
Indoor sound pressure levels should not exceed 45dBA (peak) more than 15 times a night. Sound levels should not exceed 30 dBA for continuous noise
L 10
The level met or exceeded 10% of the time. Measure of nuisance (intensive) noise.
L max
The maximum noise level recorded
L 95
The level met or exceeded 95% of the time. This is a measure of background (ambient) noise.
L eq (15 minutes)
The average level over a set period of time. Used for continuous noise (traffic etc.)
Excessive noise
Any noise that is under human control and of such a nature as to unreasonably interfere with the peace, comfort, and convenience of any person (other than the person in or at the place from which the noise is being emitted.
Where do we need to monitor?
Where motorways or major arterial highways are being planned. Where aircraft landing strips or landing pads are being planned. Where mixed residential/business activities are being allowed in existing commercial and industrial areas. Where ever major construction and demolition work is likely to take place. Where major entertainment activities such as concerts, sports events are likely to be held in open space zones.
Noise barrier design considerations
Height of barrier, tilt, source of noise, material, aesthetics, personal safety. Barries are ugly and expensive but they reduce sound levels. Reflected sound rays can become an issue with parallel noise barriers located close together which is why tilt is important.
