What are the white & gold super thin speaker things found in some toys called?

They are gold and have something that looks like a white sticker on the other side. They have two wires coming out from under the white sticker. I have found these in several toys and smoke detectors I have disassembled and need to know their name.

kelseymh7 years ago
I'd call it a piezoelectric speaker,  to sort of differentiate it from everything else out there that involving the piezoelectric effect, eg spark producing barbecue lighters, radio frequency crystals, etc.
workinprogress37 (author)  Jack A Lopez7 years ago
Thank you both! I have been wracking my brain for hours trying to figure out what it was called.
rickharris7 years ago
More properly called a Piezoelectric sounder.