voice vote

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A parliamentary vote that is determined by the relative volume of noise of those shouting “aye” and “nay.”

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A vote that is held by members calling out aye or nay, used in cases where result is not contested or at least not close and a count is not needed to determine if the motion passes.