It really depends on the nature of the device and the method of screening-- whether the device can go through the metal detector without setting it off, whether turning off the device and putting it through the x-ray machine would damage the device or impair your hearing to an unaceptable degree for you to complete the screening process-- and then there is the MMW which has damaged insulin pumps before. There is no single correct answer to this question.

The fastest way to get through the checkpoint is probably to take it off put it in your bag and though the x-ray, but that might not be a good option for you depending on how you hear without it. And it has to be x-ray safe (it probably is, but you should check with the manufacturer if possible). It is a medical device so it can be left on, but it might be faster/easier to take it off.