where in the body is the round window

The round window is in the ear.

"The middle ear is a small cavity. In many respects it is like a
narrow oblong house. Its outer wall is formed by the ear drum. The
inner wall is mainly bone but it has two windows - the oval window,
and the round window."

Parents of Hearing Impaired: Hearing Basics & Deafness
http://www.users.on.net/phisa/hearing_basics.html

"In the middle ear we see the tiny hammer, anvil, and stirrup which
form an arching chain between the eardrum and oval window on the other
side of the middle ear. The round window is just below the oval
window. Both windows are openings to the inner ear that are covered
with thin membrane."

UCSC Electronic Music Studio: Description of the Ear
http://arts.ucsc.edu/EMS/Music/tech_background/TE-03/DAN_ear

"The round window is probably the most important soft tissue interface
between the middle ear and inner ear that can be used for
pharmacological therapy of inner ear disorders."

Otoacoustic Emissions Portal: Noise induced Hearing Loss
http://web.unife.it/progetti/oae/biophysics/noise.html 

Google Web Search: "round window" + "ear"
://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=%22round+window+membrane%22+ear

I hope this information is helpful. If anything is unclear or
incomplete, please request clarification; I'll gladly offer further
assistance before you rate my answer.

Best regards,
pinkfreud

should the relative win , I will claim 50% prize money they may
collect and will go 50-50 with the researcher pinkfreud-ga

Thank you very much for the five-star rating and the tip.

Good luck to your relative in the contest!

~pinkfreud