67 Pa. Code § 157.31
The sound level measurement system shall meet or exceed the requirements of American National Standard Specifications for Sound Level Meters, ANSI S1.4—1971, approved April 27, 1971, issued by the American National Standards Institute, throughout the applicable frequency range for either:
(3) A Type S sound level meter which has the following:
This section cited in 67 Pa. Code § 157.42 (relating to ambient conditions); and 67 Pa. Code § 157.43 (relating to location and operation of sound level measurement system).