Originally Posted by
underfire
I think the unmodified A320 family sums it up<br />As part of the wake turbulence measurement, we are measuring the sound frequency of the passing ac, not just the noise level. This helps in the mitigation of noise, as a blanket insulation is overkill, but if you target frequencies, the mitigation can be very effective.
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I have a detailed frequency diagram for you: The frequency analysis there (Sonogramm) reveals a lot: the whine sound (the pair of Z shaped dark traces) is perceived far before and long after the main aircraft noise.<br />The unmodified A320 is an acoustical catastrophe in the begin of the ILS landing.<br />
Since i can't post an image yet, I invite you to go to cjoint.com and append /doc/18_11/HKxvmhuM0d1_Akustische-Analyse.jpg to that address.
Maybe someone can post the image for me?
Regards
Laszlo