First check the battery to make sure it’s inserted correctly and functioning properly. Next, check that the volume control is set to a level you can hear. Then, check the vents and receiver openings to make sure they’re not clogged with earwax or dirt, and that the tubing is connected properly. Finally, check to see if the micro-phone opening is clogged.

If the sound is distorted or inconsistent: Replace the hearing aid battery, because this could be a sign that it’s weak or defective. Get rid of any lingering moisture in the tubing with an air blower and replace any cracked cords.

If the hearing aid is emitting feedback: Check that the volume isn’t turned up too high, because that can cause your hearing aid to give off a whistling or squealing sound. Be sure the earpiece is inserted correctly into your ear and the microphone isn’t covered by any clothing.

If the above troubleshooting tips don’t resolve your hearing aid’s issue, seek hearing care professional. If any parts are missing or damaged, particularly the tubing, a visit to the audiologist for hearing aid repair is necessary.
Persistent feedback is also a sign you need to take the hearing aid to be looked at by a professional, since feedback can be a sign of an improper fit. Your ear changes shape over time, so your hearing aid can become slightly dislodged, creating a whistling or squealing sound.