Engine Sound

[Pterodactyl_imp]

What you say about back pressure control is very true. However, this is a seperate issue to noise suppression. Building an engine with back pressure control will produce efficiencies - agreed. However tweaking that to produce a quite engine inevitably leads to less efficiency. Building a noise suppression device purely for noise suppression, wether it be an inline four or a modern high bypass turbojet, will give the same result - inefficiencies.

As for the social implications I couldn't agree more.

Cheers