A psychologist could do a full battery of tests that would cover giftedness, but it sounds like she needs to find one who specializes in 2e. Auditory processing (where we are, anyway) is done through the audiology department of the hospital and requires a referral (from a family doc for an adult? not sure - my son was referred by his pediatrician). I think the first step would be for her to see her family doctor and get advice/referrals... it sounds like she has sensory issues as well.
A simple IQ test could be done through Mensa - it's faster and less expensive than hiring a psychologist (she wouldn't get as much information about her cognitive profile though).
Good luck
