| Topic: | Re:Re:Re:Re:Re:3rd runway noise in Chiswick | |
| Posted by: | Tom Pike | |
| Date/Time: | 03/02/08 12:46:00 |
| Paul, The time-averaged dB numbers have been shown in many international surveys to be the best measurement of the annoyance of noise from transport during daytime. At night the one event that wakes you up is of more importance and a different measure is used to restrict early morning flights into Heathrow. Of course all of this is necessarily based on average perceptions - you may be right that the time-averaged dB figures don't reflect your personal annoyance. But to dismiss them as a poor way of measuring disturbance is to ignore decades of acoustics research. The ANASE study you refer to specifically stated that there was no threshold to annoyance from noise - some people are disturbed at very low noise levels. The criticisms of ANASE are valid - they got their maths wrong in several places. WHO states few people are annoyed below 50 dB, but offer no evidence for this figure. But there are good reasons to think that aircraft noise below 50 dB 16 hour Leq is unlikely to disturb many in London. 50 dB's is considered a quiet urban environment and the OECD estimates 50% of the UK already experience noise from traffic of over 55 dB. Given the logarithmic perception of noise, few of this 50% are likely to discern an additional 50 dB of aircraft noise as increasing their annoyance. |