I recently got to design an app for Google Glass, and I was wondering: how much users really like that they have to speak out loud to have control over the device or to undertake an action? Are there any tests that shows how much confortable the average user is with the voice control, how much does he likes/hates it?

I crave tests! Can be anything: neuroscientific tests, psychology tests, focus groups.. whatever has shown some indication in one way or another.