i got this off from this forum
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Gradual hearing loss may occur after prolonged exposure to 90 decibels or above.
Exposure to 100 decibels for more than 15 minutes can cause hearing loss.
Exposure to 110 decibels for more than a minute can cause permanent hearing loss.
At 140 dBA noise causes immediate injury to almost any unprotected ear.
There is also the more extreme ‘acoustic trauma’, which is an immediate loss of hearing after a sudden, exceptionally loud noise such as an explosion.
Noise levels of firearms:
.22 caliber rifle 130dB
.223, 55GR. Commercial load 18" barrel 155.5dB
.243 in 22" barrel 155.9dB
.30-30 in 20" barrel 156.0dB.
7mm Magnum in 20" barrel 157.5dB.
.308 in 24" barrel 156.2dB.
.30-06 in 24" barrel 158.5dB. In 18" barrel 163.2dB.
.375 18" barrel with muzzle brake 170 dB.
.410 Bore 28" barrel 150dB. 26" barrel 150.25dB. 18" barrel 156.30dB.
20 Gauge 28" barrel 152.50dB. 22" barrel 154.75dB.
12 Gauge 28" barrel 151.50dB. 26" barrel 156.10dB. 18" barrel 161.50dB.
.25 ACP 155.0 dB.
.32 LONG 152.4 dB.
.32 ACP 153.5 dB.
.380 157.7 dB.
9mm 159.8 dB.
.38 S&W 153.5 dB.
.38 Spl 156.3 dB.
.357 Magnum 164.3 dB.
.41 Magnum 163.2 dB.
.44 Spl 155.9 dB.
.45 ACP 157.0 dB.
.45 COLT 154.7 dB.
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so, if iam wearing NRR 32 ear muff and shooting 9mm (159.8db). iam getting 127.8db to my ear. and it's still dangerous level. how this works?
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Gradual hearing loss may occur after prolonged exposure to 90 decibels or above.
Exposure to 100 decibels for more than 15 minutes can cause hearing loss.
Exposure to 110 decibels for more than a minute can cause permanent hearing loss.
At 140 dBA noise causes immediate injury to almost any unprotected ear.
There is also the more extreme ‘acoustic trauma’, which is an immediate loss of hearing after a sudden, exceptionally loud noise such as an explosion.
Noise levels of firearms:
.22 caliber rifle 130dB
.223, 55GR. Commercial load 18" barrel 155.5dB
.243 in 22" barrel 155.9dB
.30-30 in 20" barrel 156.0dB.
7mm Magnum in 20" barrel 157.5dB.
.308 in 24" barrel 156.2dB.
.30-06 in 24" barrel 158.5dB. In 18" barrel 163.2dB.
.375 18" barrel with muzzle brake 170 dB.
.410 Bore 28" barrel 150dB. 26" barrel 150.25dB. 18" barrel 156.30dB.
20 Gauge 28" barrel 152.50dB. 22" barrel 154.75dB.
12 Gauge 28" barrel 151.50dB. 26" barrel 156.10dB. 18" barrel 161.50dB.
.25 ACP 155.0 dB.
.32 LONG 152.4 dB.
.32 ACP 153.5 dB.
.380 157.7 dB.
9mm 159.8 dB.
.38 S&W 153.5 dB.
.38 Spl 156.3 dB.
.357 Magnum 164.3 dB.
.41 Magnum 163.2 dB.
.44 Spl 155.9 dB.
.45 ACP 157.0 dB.
.45 COLT 154.7 dB.
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so, if iam wearing NRR 32 ear muff and shooting 9mm (159.8db). iam getting 127.8db to my ear. and it's still dangerous level. how this works?