I was thinking about this the other day.
check this out,
Blast: Environmental Noise decibel ratings
The 357 SIG has sometimes been accused of having too much blast. Well, it depends. 357 SIG blast and flash is certainly less severe than a typical 357 Magnum revolver. Blast and flash can be controlled with various powders, flash inhibitors, and other components. A heavier bullet and/or a slower velocity can lower the noise level.
In actuality, 357 SIG ammo can easily be produced with velocities in the subsonic, transonic, or supersonic ranges (920 fps to over 1400 fps with a 4” barrel). You can have the 357 SIG sound just about any way you want it to. I fired a Ruger .22 pistol, and then I immediately fired a 357SIG pistol with a light powered 357 SIG round, followed immediately by a full powered 357 SIG round. As expected, the .22 was the quietest. The light 357 SIG round was equivalent in sound to a typical "standard" 9mm Luger round. The full power 357 SIG round was the loudest of all, with that typical supersonic cracking sound. The 357 SIG can simply speak with authority if you want it to, and with typical 125 grain factory ammo, it does.
I read an account by an officer who has been in situations of guns being fired in public. He said that in general, people are curious to see what the popping noise is and can sometimes get in the way of official business. Yet when a 357 SIG pistol was fired, everybody hit the ground in fear. A loud voice sometimes serves a purpose.
When I shoot, or when I listen to others shoot "hot" supersonic rounds in, +P 9mm, .40 S&W, or +.45 ACP, the blast sounds fairly similar with that typical loud supersonic cracking sound like a 357 SIG. As far as I'm concerned, all duty calibers are too noisy.
With recent advances in electronic ear protection, it's really a moot point. You can even have electronic ear inserts made. Unless you have just a split second to respond to a threat, use electronic ears with your gun, whether you're a Law Abiding Citizen, or a Law Enforcement Officer. Make it part of your training with easy access to your ear protection. Besides, electronic ears can help you hear normal sounds even better, while muffling out the loud noise.
Here's a short list of Environmental Noise decibel ratings:
dB
Environmental Noise
10
Normal breathing
50
Interior home noise
70
Crowded restaurant
80
City traffic
85
Hearing Damage Possible
90
Lawn mower
120
Threshold of Pain
120
Siren
130
Jackhammer
140
Jet engine at takeoff
152
.22 pistol
156
12 gauge shotgun
157
.45 ACP pistol
160
9mm pistol
164
.357 Magnum revolver
The decibel scale is a logarithmic scale, not a linear one. Each increase of 3 dB corresponds to sound that has twice as much energy (measured in pascals). Each 10 dB increase corresponds to a 10-fold increase in energy.
Loudness is a subjective thing. People might perceive a particular sound to be twice as loud when there is actually a 10-fold increase in energy. Most people cannot perceive differences in loudness of less than 3 dB.
Let's assume you have excellent electronic ear protection with an NRR rating of 29 dB. Let's use the quietest .22 caliber pistol, which has a noise level of 152 dB. Subtracting 29 from 152 still leaves you at a noise level of 123, this is still above the threshold of pain - 120 decibels. Like I said, all the calibers are too noisy.
So why do some of us still have excellent hearing after shooting for so many years? Because, gunfire is a complex, short-lived sound wave, and it doesn't travel as well through hearing protection as pure sustained tones do. The NRR rating on ear protection might actually be higher than the nominal 29 dB rating, in regards to gunfire. Yet, for "continuous" noise, the NRR rating may be reduced by as much as 50% of the nominal 29 dB rating.
So there you have it. Clear as mud.
In summary, the .45 produces less decibels than the 9mm, which produces less decibels than a full power 357 SIG. ALL of these calibers produce decibel ratings that can easily cause severe hearing loss, especially in enclosed environments. I highly recommend using one of the newer electronic ear protection devices. I know millions of people see a lot of pistol and rifle play on TV occurring outside and inside buildings where the good and bad guys don’t wear ear protection; and then they carry on regular conversations afterwards like nothing happened (no hearing loss or ringing ears, etc). Folks, that ain’t the way it is. Protect your ears for the long term. Don’t delude yourself into thinking that your ears are OK if you use a .45. Just ask a lot of old-timers who have broken ear safety rules during their lives. Be safe.
"Now hear This!", by Ralph Mroz, Combat Handguns, Sep 1998