sound off

verb3

1. •
   (informal) To hold forth about something in an opinionated manner.

   • I'm sick of his sounding off about how he thinks this country should be run!
2. •
   Command instructing a person to speak up or acknowledge something.

   • Hartman: […] Do you maggots understand that? Recruits: Sir, yes, sir! Hartman: Bullshit! I can't hear you. Sound off like you got a pair. Recruits: SIR, YES, SIR! — 1987
3. •
   Command instructing a person to confirm that they are present or that some other objective has been met.

   • Cyclops: […] X-men… Sound off … Man 1: Iceman, sounding off!Man 2: Fireman, sounding off! Man 3: Clothing-Man, sounding off! Man 4: Ability-to-Hop-Man, here! — 2004