Community response to a step change in the aircraft noise exposure around Hanoi Noi Bai International Airport.

In December 2014, a new terminal building was opened at the Hanoi Noi Bai International Airport (HNBIA) with two runways, causing a 20%-30% increase in the number of flights. Three socio-acoustic surveys were conducted in August-September 2014, February-March 2015, and August-September 2015, to contribute not only to the environmental impact assessments and aircraft noise policies in Vietnam but also to more global intervention studies. Because of the change of runway use, in addition to the increased number of flights, noise exposure at each site changed considerably among the surveys. Changes in the noise exposure from the first to the second or third survey (ΔL _den and ΔL _night ) were used as a measure of exposure change. Multiple logistic regression analysis showed that ΔL _den has a significant positive effect on annoyance regardless of ΔL _den ranges, but the effect of ΔL _night on insomnia was significant only for ΔL _night  > 0. Annoyance increase in the overall ΔL _den range may be caused by the respondents' recognition of increase in emission in addition to practical increase in exposure. More severe attitudes to airplanes around HNBIA might increase annoyance even if noise exposure decreases. Thus, the change effect clearly occurs in annoyance but partially in insomnia.