Here's a garage mechanic's trick.
Take a small section of hose or tubing and holding one end of the tube to your ear, move the other end near where the sound is.
This will help you isolate where the sound is coming from. Them you can tell what part is the most likely culprit.
To check the belt tensioner, pull the passenger wheel and wheel well off. The tensioner and pulley will be staring you in the face.
