This question pertains to NYC, but answers about how other jurisdictions define noise pollution could aid precedent or tracking down the appropriate office in New York.
Noise pollution in the city is defined by a certain decibel occurring after 6pm and before 7am. Variances are given sometimes.
Which office controls the issuance of these variances? How do they determine how many variances can be issued for a given street / neighborhood? What code or other guide is used to decide whether issuing a variance is appropriate?