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NRR adj = 75% NRR ผู้ผลิต

= 0.75 (30) = 22.5

Protected dBA = 97 – (0.75  30)

= 97 – 22.5

= 74.5 dBA

Protected dBA = 90 – [(0.75  30) - 7)]

= 90 – [22.5 – 7]

= 74.5 dBA

L’ AX = (L – SNR ) + 4
C
x
= (97 – 30) + 4

= 71 dBA