N.Y.C. Admin. Code § 24-234: § 24-234 Operation or use of sound reproduction device in or on rapid transit railroad, omnibus or ferry.

It shall be unlawful to operate or use a sound reproduction device in or on any rapid transit railroad, omnibus or ferry, other than a personal audio device with personal earphones such that sound from such earphones is not plainly audible to another individual at a distance of 5 feet or more from the source.