Sometimes if you place or cup your hand over the hearing device.
During insertion and removal of the device from your ear if the hearing device is on.
If device is not completely or properly inserted into the ear.
If the Ear Tip is the wrong size (too small or too large).
If there is wax in the ear canal.
If device setting is turned up too loud.
Tip: It takes about five seconds for your hearing device to start up when you close the battery door. This is intended to give you adequate time to insert the device in your ear without worrying about feedback.