Interesting. I see where Andy O. found that, and it's dated 7/6/06. Here's what's also currently posted on the Web 311 section of the City of New Haven website, however; wonder which version is more recent. Sec. 18-19. Noises disturbing public; enumeration of prohibited noises. No person shall make, cause or permit to be made any unnecessary noise which may tend to disturb the peace and quiet of neighbors or of the public....The operation of any machinery, equipment, pump, fan, air-conditioning apparatus, snow removal equipment or similar mechanical device, loading or unloading of vehicles, or use of any instrument in such manner or with such volume as to annoy or disturb the quiet comfort or repose of any person or persons, in any dwelling, hotel or other type of residence between the hours of 10:00 p.m. and 8:00 a.m. on any day of the week.

This may require some input by Al Lucas at OLS, but according to what Sec. 18-19 states currently:
"Sec. 18-19. Reserved.
Editor's note: Ord. No. 1422, adopted July 6, 2006, repealed former section 18-19 in its entirety which pertained to disturbing noise and derived from Ord. of 3-2-31; Ord. of 4-19-71; Ord. of 6-5-72; Ord. of 12-15-86, §§ 1, 2; Ord. of 9-21-87; Ord. No. 1262, 4-3-00; Ord. of 5-7-01. "

Furthermore, the Code of General Ordinances, as listed on the City's website, was last updated November 16, 2009. Either way, you can call LCI (they don't follow SCF), the NHPD non-emergency number @ 203.946.6316 while the alleged infraction is occurring, Hopkins School itself and see if they will better accommodate you.

Thanks!