An online listening test presented participants with simulated audio samples of aircraft noise for the current and alternative departure procedure at five locations, each affected differently by the changed procedure. These are shown in Figure 1, together with the current (grey line) and alternative (blue line) departure procedures. Those participating would not know beforehand the locations that were evaluated or which of the two sounds that were compared was the current or the alternatively departure procedure.
Figure 1: Current (grey) and alternative (blue) departure procedure and the five examined locations for the listening test
Due to COVID-19, the listening test had to be performed at participants’ home. Participants listened to the two departure procedures for each of the five locations, and after that, listened to the two procedures at the same time by alternating between them in a 4 second interval. Participants rated the sounds by 7-point Likert scale between -3 and +3(0 points if both routes were perceived equally loud). In total, 25 participants provided their subjective evaluation.
During the informational meetings afterwards, technical details related to the two departure procedures were explained, such as the noise levels calculations, technical aspects of the procedures and the listening test setup. The actual locations and which sound (the first or the last) belonged to which departure route were revealed as well. Participants were asked whether they would personally benefit from a possible change in procedure, whether they thought that the overall community would benefit and whether the community engagement strategy was helpful and valued.