33 CFR §67.10-20

1. (a)Sound signal tests must:
   1. (1)Be made by the applicant in the presence of a Coast Guard representative, who certifies the test if the procedures comply with the requirements of this section;
   2. (2)Be made with Coast Guard supplied and calibrated sound level meters and power meters; and
   3. (3)Be made in an anechoic chamber large enough to accommodate the entire sound signal, as if installed for actual use.
2. (b)The sound pressure level must be measured as a function of:
   1. (1)Distance by using a sufficient number of points to allow a far-field extrapolation of the sound pressure level;
   2. (2)Power at outputs up to and including the approximate power level necessary to comply with § 67.10-1(c);
   3. (3)Horizontal angle at increments not greater than 30°; and
   4. (4)Harmonic content to at least the third harmonic.
3. (c)In analyzing the test data to determine the minimum power necessary to produce the sound pressure level specified in Table A of this section the Coast Guard follows the procedures prescribed by the International Association of Lighthouse Authorities (IALA) in Supplement No. 3 to the IALA Bulletin of February 1969 for analysis of harmonic components and does not consider components above 1,100 Hertz as adding to the audible range.