Tinnitus is the medical term for "hearing" noises in your ears when there is no outside source of the sounds.
The noises you hear can be soft or loud. They may sound like ringing, blowing, roaring, buzzing, hissing, humming, whistling, or sizzling. You may even think you are hearing air escaping, water running, the inside of a seashell, or musical notes. Tinnitus is common. Almost everyone experiences a mild form of tinnitus once in awhile that only lasts a few minutes. However, constant or recurring tinnitus is stressful and can interfere with your ability to concentrate or sleep.
Sources
MedlinePlus - Tinnitus