If this were my car the first tool of choice would be a mechanic's stethoscope. Touch the probe to the center supports of each belt driven pulley.
If you are looking for a super quick no parts test, try removing the front acc drive belt. Does this change the noise?
2003 GT Convertible (sold & missed)
2000 GT coupe (Craigslist project. Fixed. Now my DD). Windsor to Romeo swap.