Perception of aircraft noise

 - by Roy Easson

In the January Newsletter I mentioned some of the results of a study commissioned by the BAA into the perception of aircraft noise, with the conclusion that the average noise or Leq metric used for noise regulation did not meet the requirements of residents.  The study looked at a number of alternatives, and came to the conclusion that noise event histograms were much more meaningful. The diagram, from that report, is a histogram of the number of noise events in progressive bands of noise level at a location near Heathrow.

sound

 

 

 

 

 

 

 

 

 

 

 

 

It is followed by a histogram showing the same data in terms of the number of events above the same levels.  That gives a much better indication of the nature of the effect, because it isn‘t really useful to know that there are 7 aircraft in the range 50-55 dBA Lmax when there are 128 at higher levels.

histo

 

 

 

 

 

 

 

 

 

 

 

 

To give an idea of the subjective effect, in a quiet outdoor location not affected by local road traffic, 50 dBA Lmax would be quite noticeable but unlikely to be intrusive, whereas levels in the range 55 - 60 dBA Lmax could interfere with normal conversation.  A deck chair would not be attractive with frequent events above 70 dBA Lmax, but such high levels no longer occur very often in this area because of the phasing out of noisier aircraft types.

 The BAA also has a rather ambitious programme to produce a summary of aircraft noise effects for 78 locations (each comprising a box measuring 4x4 miles).affected by Heathrow.  Greenwich is in box E9, so we might get our own noise report at some time in the future. 

To look ahead for a moment, the next consultation document on the future of aviation in the UK is expected to emerge from the DfT quite soon.  In its response to last year’s consultation on the scope of the new consultation, the Society argued for a action to reduce the environmental noise impact of Heathrow generally and for the avoidance of concentration of arriving traffic in some areas rather than dispersing it when possible.