Europa-List: Noisy Europa

[Duncan & Ami McFadyean <ami@mcfadyean.freeserve.co.uk>]

Whilst grateful for the general quietness of the Europa, inside and out, 
the cabin NACA vents and associated 'eyeball' contribute substantially 
to cabin noise. 
If during flight the vent is temporarily blocked with ,say, a finger, 
the reduction in overall noise (possibly including some external engine 
noise coming through the vent) is noticeable. Same thing can be 
experienced on an airliner.

Does anyone have any advice as to how these vents can be quietened?

Duncan McF.