Could be classic migraines with aura. I get the same things. Both visual and auditory disturbances can occur several days before onset of headache. You can also have migraine w/o the headache. Or it could be a number of other things neurological of course, e.g., mild seizures or neoplasms. I would recommend a visit to a neurologist.
Harriet B. Jacobster, Au.D., CCC-A, FAAA
Board Certified in Audiology
IHAER - Institute for Hearing Arts Education & Rehabilitation, LLC