Figure 2.4 shows the behavior of the fast exponential time averaging filter and Lmax when used properly. Figure 2.5 illustrates how the fast exponential time averaging filter responds to a typical pickleball paddle impact. Note that the time scale has been reduced for clarity. At the end of the 0.002 second impulse, the fast exponential time averaging filter has only had time to rise to a level that is 18 dB below the true sound pressure level of the impulse. The pickleball paddle impulse is so much shorter than the time constant of the averaging filter that the exponential curvature of the filter response is not even visible. It is clear that fast exponential time weighting, much less slow exponential time weighting, cannot be used to assess the noise impact of pickleball paddle impacts. The error for maximum slow exponential time weighting (1.0 second time constant) is 27 dB and for impulse time weighting (0.035 second time constant rising), 12.5 dB.
Figure 2.5. Fast Time Averaging Filter Response to a Typical Pickleball Paddle Impact
11 of 58 Spendiarian & Willis Acoustics & Noise Control LLC
12/15/2019
Made with FlippingBook - professional solution for displaying marketing and sales documents online