Just passing by, pardon me for sticking my nose in, but...
We say 'a history' but 'an historical'.
Some people do. I'm not sure when it became trendy but I wish people
would cut it out. I find it painful to hear. "An historical whatever"
or "an hallucination" is only correct if you're an 18th century Briton
or a moden Cockney and drop your aitches ("It's an 'istorical
occcasion, guvnor!").
"In modern written English, we use a before a word beginning with a consonant sound, however it may be spelled (a frog, a university, a euphemism). We use an before a word beginning with a vowel sound (an orange, an hour)." -- The American Heritage® Book of English Usage (1996).
"An historical" and a few other exceptions are acceptable
in formal writing for historical reasons, but they are holdover
varients based on obsolete pronunciations, not to be encouraged.
So: "a Hispanic person" would be the preferred usage, just like "a hissing noise".
-Tom Swiss / tms at infamous dot net