... Wear the microphone correctly, details pls check “Mike Input”2.Adjust the volume well, Turn down a little ... , Related with temperature , usage time etc. Q: What is the duration of the lithium battery, can I change ... ?A: Generally, life time of lithium battery is 2-3 years, yes, it can be changed. ... or put the battery incorrectly3.Whether the switch is open, pls contact dealer if your still can ...