Does using a Power-attack while sneaking increase your chances of being detected?

According to the Skyrim Wiki, "daggers are silent, meaning that enemies are not alerted to your dagger swings, even missed ones." However, there is generally a sound (grunt or guttural throat noise) to go along with a power attack animation.

Is this noise just for effect (like the passive spell-in-hand glow) or is the sound audible by potential victims/enemies?

I think the power attack is just as silent as a normal swing, the grunt/yell is purely for effect. I went up behind an enemy and whiffed a bunch of power attacks on purpose and he had no reaction whatsoever, then I finished him off with a power attack and a nearby patrolling enemy didn't react.

I have to add an addendum to this:

Power attacks can sometimes push your character forward a little bit on the swing, and this can cause you to be detected before the attack connects, making you lose the sneak attack bonus. Make sure you are standing far back enough for this to not happen.