Schiphol Holland Noise Abatement.

These noise-absorbing ground ridges were constructed sometime after 2012 in order to reduce noise from aircraft take-offs. They have had the effect of reducing noise in Overbos and Bornhol by 5.5 db. (A,B or C scale not specified.)







www.schiphol.nl/en/schiphol-as-a-neighbour/page/landscape-design-plan-to-combat-noise-nuisance/



Schiphol Holland Noise Abatement..kmz (1.02 KB)

I think the cause of the ground ground noise is the wake turbulence behind the aircraft. These can spread for kilometers as a dull rumble, swoosh or hiss.

Here is a physics problem for you.  What frequencies of the aircraft noises are most attenuated?  Hint:  The ridges are 11 meters apart.  

Sept 4, 2020 20:00:24 GMT larryc1 said:

Here is a physics problem for you.  What frequencies of the aircraft noises are most attenuated?  Hint:  The ridges are 11 meters apart.  

The earth walls are simple acoustic diffusers. For diffusers with a prismatic structure, roughly speaking, the scattering / extinction (phase shift) is highest at λ ... 2λ (wavelength). So with a distance of about 11 m between the ridges, probably 15 to 35 Hz.

Willi - go to the head of the class!