N-above (or N-above noise) contours illustrate the average number of aircraft noise events per day that exceed a specified sound level.
The National Airports Safeguarding Framework, suggests that an outdoor sound level of 70 dBA corresponds to an indoor noise level of approximately 60 dBA with the windows open, which is considered to be the sound level at which conversation and other indoor activities can generally be disturbed.
Perth Airport recognises that residents enjoy an outdoor lifestyle during the summer months, which is often reflected in building construction. As a result, Perth Airport has adopted an outdoor sound level of 65dBA for noise modelling, which correlates to an indoor noise level of approximately 55 dBA.
Importantly, the N-above contour map represents an average day and not a typical day. The actual number of flights over your location will vary, with some days experiencing more movements and some days experiencing fewer.
The number of flights varies by the time of day, day of the week and the season. Perth Airport typically experiences morning and afternoon peaks which are larger during the work week as there are more flights servicing fly-in/fly-out and other business-related traffic. The weather and wind direction typically dictate which runways – and therefore flight paths – are used.