4. Analysis
4.1 Ball Sound Pressure Level Comparison The most direct way to compare the effect of the ball on the sound produced by the paddle impacts is with the mean sound exposure levels at the two test locations on the axis of play. These levels can be compared directly since they were measured at the same distance with similar ground between the courts and sound level meter.
Mean SEL
re Dura Point 3 (dBA)
Point 2 (dBA)
Point 3 (dBA)
Point 2 (dBA)
Mean (dBA)
Ball Foam Quiet
45.8 43.0 -9.3 -8.3 -8.8 49.6 50.3 -5.6 -1.0 -2.7 51.5 51.0 -3.7 -0.4 -1.7 55.2 51.3 0.0 0.0 0.0
Monarch
Table 4.1.
Onix
Dura 40
Comparison of Balls by Mean Sound Exposure Levels
Table 4.1 shows the mean SEL at the two test locations from the previous chapter and the difference in SEL relative to the Dura ball. The mean SEL results are very consistent for the Monarch and Onix balls. The Foam Quiet ball and Dura had a more consistent level difference over the two test cases. Both types of comparison show the same rank order from quiet to loud. The Monarch and Onix are in the middle with similar acoustical performance, the Monarch being imperceptibly quieter. The Foam Quiet ball is five to seven dBA quieter. In one test the Dura performed similar to the Monarch and Onix, in another it was about four dBA louder than the Onix. Overall the Foam Quiet ball would be expected to be eight to nine dBA quieter than the Dura and five to seven dBA quieter than the Monarch and Onix. A review of the data showed that the differences between Points 2 and 3 for the Foam Quiet and Dura balls were in fact typical of the individual measurements and not simply introduced by the selected window for assessing the SEL. Variation such as this is common with field measurements. It was noted that the Foam Quiet ball made less of a pop than the other balls and produced less reverberation. This can have some effect on the sound exposure level. The reverberant tail is the
26 of 58 Spendiarian & Willis Acoustics & Noise Control LLC
12/15/2019
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