To hear them, you need to modify the sound.cfg (found in the FSX\Captain_Sim\sso folder).

Change this:

[Common]
Refresh.Time=10
Sound.Directory=Captain_Sim\sso\sound
SoundOffWhenSimIsSlew=1
SoundOffWhenSimIsPaused=1
SoundOffWhenSimDialogIsOpen=1
SoundOffWhenSimSoundIsOff=1

to this:

[Common]
Refresh.Time=10
Sound.Directory=Captain_Sim\sso\sound
SoundOffWhenSimIsSlew=0
SoundOffWhenSimIsPaused=1
SoundOffWhenSimDialogIsOpen=1
SoundOffWhenSimSoundIsOff=1

These entries are the first entries in the file, so you won't need to search for them. ;)