Costco does use REMs. Also called, probe-microphone measurements, REMs allow audiologists or hearing specialists to confirm that your hearing aids work well inside your ears. REMs examine the acoustics, or sound pressure, in a patient’s ear when wearing a hearing aid. Our medical reviewer, Dr. Hadassah Kupfer, told us REM services “can significantly improve and customize your hearing aid settings. It can only be done in-person, never over the web.”