This study will try to identify the genetic causes of hereditary hearing loss or balance disorders.

People with a hearing or balance disorder that affects more than one family member may be eligible for this study. They and their immediate family members may undergo some or all of the following procedures:

• Medical and family history, including questions about hearing, balance and other ear-related issues, and review of medical records.
• Routine physical examination.
• Blood draw or buccal swab (brushing inside the cheek to collect cells) - Tissue is collected for DNA analysis to look for changes in genes that may be related to hearing loss.
• Hearing tests - The subject listens for tones emitted through a small earphone.
• Balance tests to see if balance functions of the inner ear are associated with the hearing loss - In one test the subject wears goggles and watches moving lights while cold or warm air is blown into the ears. A second test involves sitting in a spinning chair in a quiet, dark room.
• Photograph - A photograph may be taken as a record of eye shape and color, distance between the eyes, and hair color.
• Computed tomography (CT) and magnetic resonance imaging (MRI) scans - These tests show the structure of the inner ear. For CT, the subject lies still for a short time while X-ray images are obtained. For MRI, the patient lies on a stretcher that is moved into a cylindrical machine with a strong magnetic field. The magnetic field and radio waves produce images of the inner ear. The radio waves cause loud thumping noises that can be muffled by the use of earplugs.