N.Y. Public Authorities Law § 1204-A
1. As used in this section, unless another meaning is indicated by the context: a. "Authority" means the New York City Transit Authority. b. "Subways" means all rail rapid transit systems operated by the authority including but not limited to rolling stock, track and track beds, passenger stations, tunnels, elevated structures, yards, depots, and shops. c. "New cars" means all those cars the purchase and/or construction of which is contracted for subsequent to the enactment of this section. d. "Screech" means any noise generated by wheel-track interactions on curves or by brake application and which is a prominent discreet tone above 1000 Hertz as defined by the American National Standards Institute specifications (ANSIS1.13--1971). e. "Sound pressure level" means twenty times the logarithm to the base ten of the ratio of the root mean squared pressure of a sound to a reference pressure of twenty micropascals. The unit applied to this measure shall be the decibel (dB). f. "A-weighted sound level or (dBA)" means the sound pressure level measured by the use of an instrument with the metering characteristics and A-weighting frequency response prescribed for sound level meters. The sound level measurement system must meet or exceed the requirements of the American National Standard Institute Specification for Sound Level Meters ANSI S1.4--1971, approved April twenty-seventh, nineteen hundred seventy-one, throughout the applicable frequency range for either:
(c) A Type S sound level meter which has: