Section 67.10-20 - Sound signal tests(a) Sound signal tests must:(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) Be made with Coast Guard supplied and calibrated sound level meters and power meters; and(3) Be made in an anechoic chamber large enough to accommodate the entire sound signal, as if installed for actual use.(b) The sound pressure level must be measured as a function of:(1) Distance by using a sufficient number of points to allow a far-field extrapolation of the sound pressure level;(2) Power at outputs up to and including the approximate power level necessary to comply with § 67.10-1(c) ;(3) Horizontal angle at increments not greater than 30°; and(4) Harmonic content to at least the third harmonic.(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.View Image