shows the annoyance curves for four traffic modes together with respect to Ldn.
At a given exposure level, both military and commercial aircraft cause the high- est %HA, followed by railway and road traffic.
Overall the railway curve lies below the aircraft curves and above the road traffic curve, indicating a substantial difference between these sources.
The differences between the curves for four traffic modes were considered to be caused by non-acoustical factors as well as acoustical factors.
For example, fear of a plane crash may cause people to be more annoyed to aircraft noise than others.