Review on 🔊 18W Waterproof Bluetooth Wireless Voice Amplifier with UHF Portable Microphone Headset - Small PA Speaker System for Teachers, Classroom Speech, Outdoor/Indoor Events, and more by Jair Baltrusch

In the first 3-4 minutes a lot of noise could be heard. Then the sound became clearer. Except for 4-5 one second breaks and occasional (very rare and short) hissing noises it was great. The speaker was able to speak for 90 minutes without any problems. In 90 minutes, the battery went from 100% to 78%. Pretty good. I held the speaker about 5 meters away from the speaker and there were no issues with feedback.