Hearing the complaints from eco-friendly group D.E.H.T.A. (and after charging them a substantial amount of coinage) the Goblin engineers have focused their efforts on the engineering gyrocopter this time! The impact being they have become silent (and debatably more friendly for the environment!)
Note: At some point in 2015 the extract location changed to the root WoW folder
Simply extract the downloaded file to
*World of Warcraft Directory*\
Old version:
*World of Warcraft Directory*\Data\
or for some people
*World of Warcraft Directory*\Data\enUS\
Now you never have to hear another gyrocopter sound ever! (Including possibly non-player gyrocopters!)