Abstract
This study focuses on perceived activity disturbance evaluated by
participants who are subjected to the repetition noise of current
aircraft and modified aircraft in regard to tonal quality. A previous
study devoted to the sound quality of aircraft noise revealed that
one of the most important perceptive features is the emergence of
Doppler shifted tones. Six 20-min sound sequences were created combining
two variables: number of aircraft (N1 with six aircraft and N2 with
10 aircraft plus one sequence without aircraft N0) and tonality (sequences
with current aircraft, sequences with +5 dB-amplified tonality and
sequences with −5 dB-attenuated tonality). For all sequences, the
equivalent sound level and the peak level of the loudest event are
constant, except for the sequence without aircraft. Sixty-three subjects,
attending two different sequences in one session, rated on a category
scale the level of activity disturbance due to the noise environment
when carrying out memory and concentration tasks. The order of presentation
was controlled as an additional variable in the variance analyses.
The perceived activity disturbance is significantly influenced by
the equivalent sound level. The influence of the number of aircraft
flyovers is statistically significant at the 5% level. High tonal
components have no effect on perceived disturbance. Memory and concentration
performances, measured by number of incorrect or correct answers,
are influenced only by the order of presentation, revealing the importance
of the learning effect. Reaction time, which is influenced by the
equivalent sound level, seems better adapted for measuring the effect
of noise on task achievement. These results are discussed in regard
to related research.
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