THE TOP EDUCATOR in the nation's largest public school system formally proposed making free condoms available to every high school student in the city without parents' consent in order to curb the spread of AIDS. New York City Schools Chancellor Joseph Fernandez presented the condom proposal, part of a larger plan for fighting AIDS, to the Board of Education at a public meeting Wednesday . . . HIGH-IMPACT AEROBICS enthusiasts bouncing their way to trim tummies and tight tushes may also be jolting their inner ears into episodes of vertigo and inviting hearing loss from loud workout music, a doctor says. Dizziness, ringing in the ears and loss of balance were found among aerobics teachers and others who do the popular form of exercise frequently, Dr. Michael I. Weintraub of New York Medical College wrote in The New England Journal of Medicine.