Document nBoBXOZL5ay1L461Nrv4ROYR

INDUSTRIAL NOISE Standards Association and the Internationa] Organization for Standardization TABLE 43-A PREFERRED FREQUENCIES FOR ACOUSTICAL MEASUREMENTS (American Standard SI 6-1960) Center Frequency (c) 315 630 125 250 500 1,000 2,000 4.000 8.000 16,000 Overall Bands (c) 22 3 to 446 44 6 to 89 2 884to 1770 1770 to 3540 3540 to 707 0 707 0 to 1,414 0 1,414 0 to 2280 2,828 0 to 5,6560 5,656 0 to 11,3100 11.3100 to 22,620 0 All pass Some analyzers are designed to measure sound pressure level in one-third octave bands or in narrow bands of constant width, for example, 5 cycles or 20 cycles Such measurements are entirely acceptable, but are not necessary for hearing conservation purposes The sound level meter and octave-band analyzer do not measure impulsive noise levels accurately. If a noise-exposure meludes impulsive noises, qualified acoustical engineers should make the noise measure ments with special equipment Noise level measurements for bearing con servation purposes should always be made at the approximate position of the employee's most exposed ear To take account of the variations in noise levels produced by changes in operational schedules or proce dures, repeated measurements should be made during a single day as well as on dif ferent days of the week Noise-exposure measurement should be undertaken only by personnel with training and experience m making physical meas urements with electronic equipment (Read ers wishing further information on the techniques of noise measurement should