2002-3 Honda Odyssey Info.
 

"Do you get a buzzing noise under the hood of your 2002-2003 Honda
Odyssey, especially with a hot engine and air conditioner on? According to
Technical Service Bulletin (TSB) 03-052, it's probably the serpentine belt
amplifying the normal buzzing of the alternator. Replace the belt with a
revised type."

I learned the above info. from Popular Mechanics magazine and decided to
pass it along in case any Odyssey owners have this problem.