What's the name of the small megaphone that university teachers use to pin on their collars? Where can I buy it?
Generally speaking, a standard speaker is just an earphone microphone. You're talking about a collar microphone, which needs to be equipped separately. Remember, because the sensitivity of the collar microphone is much higher than that of the headset microphone, so don't turn the volume too loud, or you will scream. I used victory speaker and collar microphone, which had a good effect, loud voice and clear sound quality. I hope I can help you.