At least some content in this article is derived from information featured in the latest update of Pottermore. As such, spoilers will be present within the article. Please take care when reading this article if you have not yet been through the latest update.
Vouvouzelas are a Muggle musical instrument in the shape of a plastic horn that produces a singular loud noise. Wizards consider them the Muggle equivalent of Dissimulators.
Behind the scenes
Oddly, Pottermore uses the spelling "vouvouzela", which is an obscure French spelling of vuvuzela, the spelling used in English.