Document D46MenGo3vmbBRm1akxqDLKQ

46--Safety Engineering Tables graph), shall be made in order to ensure that the audiometer displays no evidence of distor tion, unwanted sound, or other technical prob lems (e) The general function of the audi ometer shall be checked, particularly m the case of a self-recording audiometer (m) An exhaustive calibration shall be per formed at least every five years This shall include testing at all settings for both ear phones The test results must prove un equivocally that the audiometer meets for the following parameters the specific requirements stated in the applicable sections of ANS S3 6 as noted m parenthesis (a) Accuracy of decibel level settings of test tones (Sections 4 14 1 and 4 14 3), (b) Accuracy of test tone frequencies (Section 412), (c) Harmonic distortion of test tones (Section 4 13), (d) Tone-envelope characteristics, i e, rise and de cay times, overshoot, "off" level (Section 4 5), (e) Sound from second earphone (Section 4 4 2), (/) Sound from test earphone (Sec tion 4 41), (g) Other unwanted sound (Sec tion 4 4 8) (iv) A record shall be made of each audi ometer calibration, and shall include the re sults of all measurements obtained (h) Hearing protector reduction factor "R." The noise reduction factor "R" of a hearing protector shall be determined by one of the methods in (1), (2), or (3) of this paragraph Method (1) is an exact mathematical method. Method (2) is an approximation using known octave band levels, and Method (3) is an ap proximation where only the A-weighted level for the environment is known The pure tone attentuation, and standard deviation vs fre quency characteristics of the hearing protec tor (normally supplied by the manufacturer) shall have been determined in accordance with ANS Z24 22 (1) Method 1 --Exact reduction factor "R " R = La -- 10 log S where (l) L, = the A-weighted slow level measured m the environment (u) S = antilog 0 1 (L, -- Q,) + antilog 0 1 (L. -- Qj) + antilog 0 1(L, -- Q.) + antilog 0 1 (L, -- Q) + antilog 0 1 (Ls -- Q,) + anti log 0 1(L -- Q,,) + antilog 0 1(Lr -- Qt), where 1490 (a) Q, through Q, are defined m dB as Q, = attenuation at 125 Hz, plus 16 2 dB, minus 2 standard deviations Q. = attenuation at 250 Hz, plus 8 7 dB, minus 2 standard deviations Q, = attenuations at 500 Hz, plus 3 3 dB, minus 2 standard deviations Q, = attenuation at 1000 Hz, minus 2 stand ard deviations Qs = attenuation at 2000 Hz, minus 1 2 dB, minus 2 standard deviations Q. = average of attenuation at 3000 and 4000 Hz, minus 10 dB, minus 2 standard deviations Q- = average of attenuations at 6000 and 8000 Hz, plus 1 1 dB, minus 2 standard de viations (b) L, through Ir- denote the octave band levels measured m the environment at 125, 350, 500, 1000, 2000, 4000 and 8000 respec tively (2) Method 2--Approximate reduction fac tor "R" using octave levels (i) Adjust each octave band level to obtain the A-weighted equivalent (n) Subtract from each octave band level the mean protection value, adjusted by two standaid deviations (m) Obtain the overall A-weighted sound level leaching the eardrum by summing the values obtained in (u) of this subparagraph Addition of these logarithmic values mav be conveniently accomplished by a semi-graphical procedure using Figure 1910 95-2 Step Action (1) Using the A-weighted octave band levels calculated in (u) of this subparagraph, subtract the "second highest value" from the "highest value", (2) Enter the curve of Figure 1910 95-2 at the point corresponding to the difference value calculated in (1), located on the houzontal scale, (3) Follow a horizontal from the point on the curve found m (2) to the vertical scale, (4) Add the value found at the vertical scale m (3) to the "highest value", (5) Repeat steps (1) through (4) using the