Are shouts affected by perks?

It's possible that ones like Fire Breath might benefit from the corresponding destruction perks, but it's not obvious how most could interact.

One example I know is Slow Time shout. The shout's duration increases with the Stability perk in alteration and also with Fortify Alteration potion. You can make it so that the shout duration is longer than the shout cooldown.

Stability: Increases Slow Time duration by 50%

Dismay: May be affected by illusion perks

Quiet Casting: Affects all shouts

Augmented Flames/Frost: Affects Fire/Frost Breath

This one has always baffled me. A "quiet" SHOUT?