The control group (Group 2) will consist of 150 subjects without MS who are matched to the patient group with respect to age (± 5 years), to gender and to audiometric configuration (within ±10 dB Hearing Level for the octave test frequencies from 500 through 8000 Hz). Subjects in Group 2 will be recruited from the VA audiology clinic and from a cohort of more than 360 subjects and patients who have been used as controls in five other studies. Both males and non-pregnant females will be recruited in equal numbers. Minority individuals will be recruited in accordance with recommendations for proportional minority representation established by the Office of Human Research Accountability and the Minority Affairs Program. The protocols will be explained verbally by the investigators, and restated in consent forms approved by the VA IRB, and signed by the subject, by the investigator and by a witness.