Parts of "Sound Advice", Musani (Aud.D.) 2001
www.keepandbeararms.com/downloads/SoundAdvice.doc
A sound decibel (dB) is a unit for measuring a *very* wide range of sounds.
It's a scale based on exponents (logarithmic), and there is a 10-fold increase
in "noise energy" for every 10 dB increase, so every dB is important.
But an increase of 10 dB only doubles the "perceived loudness level"
[partly due the adaptive need to hear quiet sounds].
Some typical sound levels ...
Gunshot : 150dB _ _ _ _ _ _ _ _ Jet Plane : 140dB
Riveting Steel Tank: 130dB _ _ _ _ _ Automobile Horn: 120dB
Woodworking Shop: 100dB _ _ _ _ _ _ Soft Whisper: 30dB
Gunfire often a cause ear injury, including bursting, tearing, fusing, or
severe mechanical damage to the inner ear cells, structures, and auditory
pathways. This can mean serious and permanent hearing loss.
Below 140dB, different types of sounds generally produce the same hearing loss.
But above 140 dB, impulse noise creates more damage than would be predicted.
Between 90 and 140 dBA ('dBA' is filtered to simulate human sensitivity),
the inner ear is damaged metabolically, rather than mechanically, and causes
injury depending on the level and duration of exposure, developing slowly
over time. But acoustic trauma might occur from just one unprotected exposure
to gunfire noise.
Under 90 dBA, the ear has a natural protective mechanism to reduce its
sensitivity to low frequency impact sounds through a middle ear reflex.
But a delay of 1/3 to 1/2 second is required to set this protection fully
in operation. Many man-made sounds, such as explosions from guns, occur so
quickly that our middle ear's protective mechanism cannot respond quickly enough.
Peak sound from rifles/shotguns can be 132dB-SPL (sound pressure level units)
for small-caliber, to more than 172dB-SPL for high-powered firearms.
Gun noise is America's most serious non-occupational noise hazard.
A single shot from a high-powered gun is equivalent to almost 40 hours of
exposure at 90dBA. (Clark & Bohne, 1999; NRA, 1999).
SHOTGUNS (dB average)
.410, 28" barrel: 150dB _ _ _ 18 " barrel: 156.30dB
12 Gauge, 28" barrel: 151.50dB _ _ 18 " barrel: 161.50dB
RIFLE
.223, 55gr, 18 " barrel: 155.5dB
.30-30, 20" barrel: 156.0dB
.30-06, 18 " barrel : 163.2dB
Centerfire PISTOL [barrel length is very relevant]
.32 Long : 152.4 dB _ _ _ _ .32 ACP: 153.5 dB
.38 S&W : 153.5 dB _ _ _ _ 45 Colt: 154.7 dB
.25 ACP : 155.0 dB _ _ _ _ .44 Spl : 155.9 dB
.38 Spl : 156.3 dB _ _ _ _ _ .45 ACP: 157.0 dB
.380 --> --> 157.7 dB _ _ _ _ 9x19 : 159.8 dB
.41 mag: 163.2 dB _ _ _ _ _ .357 mag: 164.3 dB
Even if some sounds might not seem as loud to you now, it's still critical to
wear hearing protection, since the hearing you have left can still be harmed.
Add to this that our hearing gets worse just from the normal aging process.
Gun muzzle brakes and ports dramatically increase the level of noise exposure.
