In its 1999 Guidelines for Community Noise, the World Health Organization (WHO) declared, "Worldwide, noise-induced hearing impairment is the most prevalent irreversible occupational hazard, and it is estimated that 120 million people worldwide have disabling hearing difficulties".
Today's traffic noise policies are often influenced by guidelines for acceptable noise levels rather than welfare efficiency.18 To gain acceptance for the use of BCA among policy makers it is therefore important not only to provide monetary welfare measures but also to inform about strengths and weaknesses, policy implications of using different values, and potential use.
The proposed prediction method had high calculation precision, and the predicted results provided useful theoretical support and practical guidelines for engineering noise control of box-shaped structures.
For example, the WHO recently adopted a set of health-based guidelines for nighttime noise exposure that are much lower than previously recommended levels (WHO 2009).
Some researchers, for instance Birgitta Berglund, a professor of psychology at Stockholm University in Sweden and editor of the World Health Organization's 1999 Guidelines for Community Noise, suggest unwanted sound exposure can cause hearing loss, fatigue, loss of balance, nausea, reduced sex drive, headaches, and mental disorders.
We propose some design guidelines for low-noise multi-wavelength optical systems, through an accurate prediction of noise growth in each channel, including the effects of map asymmetry and third-order dispersion.
On the other hand, the ideal WHO guideline for nighttime outside noise levels of 40 dB may be too restrictive in areas where buildings are heavily insulated.
There is a need to establish guidelines for conventional railway noise in Japan.
