§325.23 Type of measurement systems which may be used.

The sound level measurement system must meet or exceed the requirements of American National Standard Specification for Sound Level Meters (ANSI S1.4 1971), approved April 27, 1971, issued by the American National Standards Institute, (1) throughout the applicable frequency range for either:

(a) A Type 1 sound level meter;

(b) A Type 2 sound level meter; or

(c) A Type S sound level meter which has —

(c)(1) A weighing frequency response;

(c)(2) Fast dynamic characteristics of its indicating instrument; and

(c)(3) A relative response level tolerance consistent with those of either a Type 1 or Type 2 sound level meter, as specified in Section 3.2 of ANSI S1.4 1971.