Sound Level Chart
Use the date/time fields to select the range of time of interest to you. If the dates are out of range, they will be adjusted for you. Once the graph is rendered, you can look at the actual sound levels (dark blue). The background levels (green) represent the absence of overflight. Any sound levels over the trigger (orange) represents a disturbance. Max (red) represents peak disturbances. After selecting what to view, click on MakeChart to redraw the chart.
Disturbances undergo further analysis to reject any that are too short or too long to be an aircraft overflight. This is performed when the disturbance list is created. You may specify a daytime and nighttime disturbance threshold to further filter events, and specify when those thresholds apply. The defaults are: daytime is 50dBA starting at 7AM, nighttime is 40dBA starting at 10PM. An ambient noise mask filter threshold may be set, This masking filter indicates how much louder above the ambient or background sound levels a noise event must exceed before it is noticable to you. The default masking value is 6dBA.