The squealing that you or those around you hear is called feedback. Feeback may occur because something has changed with the way the hearing aid fits in your ear. This can be because your hearing aids need to be cleaned, your ears have accumulated debris in the canal, or your ears have grown (your ears continue to grow as you age).
If you are experiencing feedback, try cleaning your hearing aids and your ears themselves. If that does not stop the feedback, consult your hearing care provider.