Sound Data Analysis
While a typical complete acceleration event lasts for
less than 0.01 seconds, the radiated sound in our airplane
inspect tests lasts for about 0.15~0.2 seconds for the same
impacts. We took 2048 sound amplitude samples (over~0.043 seconds) for the following data analysis, so the
granularity in frequency spectrum analysis is 23.4 Hz.
From these sound samples (using the identical impacts
we used in force analysis), we also calculated 1/3 power
accumulation ratio factor , with frequency components
from 23.4 Hz up to 8 kHz (for comparison with
Pfund’s practice, 10 kHz as shown in [10]). The mean and
standard deviation are shown in Table 2.