meg·a·phone 
(mĕgə-fōn′)
(mĕgə-fōn′)n.
1. A funnel-shaped device used to direct and amplify the voice.
2. A bullhorn.
tr. & intr.v. meg·a·phoned, meg·a·phon·ing, meg·a·phones
To transmit (a message) or speak through a megaphone.
meg′a·phonic (-fŏnĭk) adj.