0 present participle of quieten --
1 to (cause someone to) become calmer or less noisy: --
The barking dogs quietened (down) when they recognized me.
Will it be published, and will it cover the possibility of retro-fitting with quieter engines of a new type, as well as other measures for quietening existing aircraft?
As to retrofit, current studies suggest that the scope for quietening existing engines may not be as great as previously thought and the cost is very high.
Because no action will be taken by the airlines without some initiative, and no one will spend money voluntarily on quietening their aircraft, unless some action is taken.
It may be that the amount was artificially increased during the excitement of the war and that we are now naturally quietening down and the amount is decreasing.
Thirdly, it is not just a matter of quietening the engines.
The technology which we have thereby learned, about quietening engines, has been extremely valuable.
At the other end of the scale is quietening the engines.
With the introduction of the initial scheme, attention is now being turned to the possibility of quietening current types of aircraft.
