Applications - Soundscape Ecology: Principles, Patterns, Methods and Applications - page 277

10.11 Aircraft Noise in National Parks
The noise produced by jet aircraft is becoming a growing concern around the world,
and regulations have been provided most of the developed countries. We have
already discussed the problem of aircraft noise in Chapter 6. In particular, natural
parks in the backcountry are areas very sensitive to noise intrusion. In urban areas,
the dose-response relationship between dwellers and noise sources, faced with
efficient parameters and metrics (e.g., day-night average sound level; DNL, or
L dn ), is well correlated with the percent of the surveyed residential population
complaining of noise annoyance. This parameter is insufficient for park visitors
who are not exposed to noise by aircraft or ground transportation machines for a
prolonged time as in the proximity of airports or urban areas.
In the US a Congress mandate of 1987 has been received by the U.S. National
Park Service in the 1990s in collaboration with the U.S. Federal Aviation Adminis-
tration (FAA): 2,600 questionnaires when processed in different parks and reported
by Anderson et al. ( 2011 ) found that the effects of aircraft noise on visitors largely
depend on the characters of the visitors as well. The dose-response relationships are
important but significant acoustic variables are also the total aircraft Leq during the
visit, the energy percentage of that total from helicopters, and the energy percentage
of that total from fixed-wing aircraft.
In such type of investigation resulted important also non-acoustic variables that
are significant:
Visitors for whom natural quiet is very or extremely important are 10 to 50 dB more
sensitive to aircraft noise than other visitors.
Visitors that have visited the site before are 20 to 35 dB more sensitive to aircraft noise
than other visitors.
Visitors in adults-only groups are 10-to-20 dB more sensitive to aircraft noise than other
visitors.
Visitors on short hikes are 35 to 70 dB more sensitive to aircraft noise than other
visitors.
High-altitude jet aircraft produced annoyance for 16 % of visitors for 40 dB, but
tour aircraft noise annoyed 36 % of visitor for 40 dB.
Monitoring the effect of aircraft noise on visitors in natural areas is becoming an
urgent matter. The increase of the number of flights over natural areas exacerbates
the relationships between ground-based recreationists and aircraft civilian and
military air traffic, as reported by Booth et al. ( 1999 ). To reduce the impact of
aircraft overflying, a monitoring scheme has been presented by Booth et al. ( 1999 ).
The administration of a short questionnaire represents an efficient tool to investi-
gate the status of aircraft-borne acoustic pollution. In remote areas of the parks the
questionnaire was distributed for a self-pickup.
The questionnaire was regarding:
General likes and dislikes
Whether aircraft were noticed during the visit