Annoyance and task performance during a single high-level aircraft noise and multiple lower-level aircraft noises

Measurement of noise exposure tends to focus on sound level; however, the number of noise events might also influence health and cognition. We investigated how the distribution of noise events over time influences experiences of loudness, annoyance, and task performance.

We presented recordings of a passenger aircraft flying overhead, either as a single 15-s overflight at 80 dB LeqA 15s or four 15-s overflights at 60 dB LeqA 15s . Levels were chosen on the basis that an increase of 10 dB doubles the perceived loudness, thus four stimuli at 60 dB might be expected to seem as loud as a single stimulus at 80 dB. Participants performed a mental arithmetic task during half the stimulus presentations and rated their perception of loudness and annoyance to every presentation, while pulse and skin conductance were monitored.

Overall, the single 80-dB-flight stimulus was perceived as louder ( F  = 124.519, P < 0.001) and more annoying ( F  = 63.530, P < 0.001) than the four 60-dB flights. Noise did not influence task performance; however, there was an interaction ( F  = 36.256, P < 0.001) in that while doing the task, the four 60-dB flights were perceived as louder and more annoying than without the task, whereas the single 80-dB stimulus was less loud and no more annoying than without the task. Physiological markers were consistent with the intent that the task be difficult and that the single high-sound-level stimulus was more stressful for participants.

Results showed that, at the levels used, the higher-level stimulus influenced ratings of loudness and annoyance, even though the lower-level stimulus occurred four times as often. Future research exploring systematically the relationship between the number and sound level of overflights and the reactions they induce is needed.