This usually means that the device playing the music is not turned all the way up.
If the music is playing on a phone, laptop or tablet, make sure that the volume is turned all the way up on both the hardware and the software. (turn your headphones down before you do that)
If it is a DJ-controller/audio-mixer-board, that doesn’t need to be turned all of the way up, but it still does need to be turned up higher than you have it.
Make sure the DJ keeps her Silent Disco headphone volume at no higher than 50%. If she has headphones much higher, then she is going to be setting the controller/mixer/laptop/phone/tablet output volume too soft.
Under optimum circumstances the reception distance is 300 meters. That is more than three football fields. Also, because these use FM signals, they work through obstacles like walls. It doesn’t have to be line of sight.
No, you can’t change the batteries. They are rechargeable lithium-Ion Batteries that are hardwired in. They come to you fully charged so you don’t have to charge them unless your party is longer than ten hours.
They have proprietary charging ports so you can’t recharge them without our chargers. We do send you some chargers in case you need them.