Subsonic means quieter... right?

[Jkwas]

I keep a 38spl revolver at bedside, because it's way quieter than a .357 mag.   My 3in barrel taurus 9mm is a quieter gun to shoot than my 4.5in 9mm Ruger.  I suspect it's because the round isn't breaking the sound barrier out of the short barrel vs the long barrel.   If that's the case,  Subsonic 147gn 9mm should be quieter than screaming 124gn ammo, right? 
What I'm driving at is this:  Does it make more sense to use the slower, heavier round in a home defense situation in order to minimize hearing loss?    Of course the right thing to do is to park a set of muffs on the bed post. 

[TSB]

The average decibel of noise from a gun shot is 146 db, more than enough to cause permanent damage to your hearing.  Repeated exposure will futher damage the hearing and is not repairable.  Similar to back injury, loss of hearing is cumulative.

The speed of sound is approximately 1132 ft per/second and most 9 mm ammo exceeds that muzzle speed.  Since the timing of the explosion so closely matches the timing of the projectile leaving the barrel, I doubt it matters much.  My .45 at 850 fps sounds just as loud as my 9 mm at 1250.  Without precise timing instruments and db meters, you probably can't tell the difference. 

Indoors, with the echo off the walls, a gunshot will definately sound louder than it does out of doors.

[Rastus]

3" barrel it won't matter whether it's subsonic or not.  A 45 ACP is subsonic...still a loud booger.

Doesn't make sense to me to make a change for hearing loss. 

Plywood state...Florida?  Supressors are legal in Florida.  That would be the right best thing to get to prevent hearing loss...get a supressor.

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[Big Frank]

Subsonic with a suppresor can be very quiet. With supersonic ammo the bullet makes a sonic boom when it breaks the sound barrier. Just like a jet aircraft.

[ericire12]

Yes, anything below 1000 fps is not as loud because it is not breaking the sound barrier.... But the difference in sound may not really be that noticeable.... you are still shooting a gun after all.

For home defense, I would concentrate on firing as few rounds as possible to save your hearing -- i.e. put down your target the first time so you dont need any follow up shots  

For personal defense rounds you need to focus more on finding a round that will deliver the most energy on your target for the particular caliber you  are using -- there is an inflection point where less mass and more velocity will actually equal less energy. Additionally, you need to find a round that will also retain as close to 100% of its weight as possible..... lack of weight retention means that the energy is also being lost -- A round with 100% weight retention is delivering 100% of the advertised energy on target.

[Sponsor]

[Big Frank]

A round with 100% weight retention is delivering 100% of the advertised energy on target, if it doesn't pass through the target.

[ericire12]

if it doesn't pass through the target.

True.

And if it does then there will be twice as much blood!

[tombogan03884]

I keep a 38spl revolver at bedside, because it's way quieter than a .357 mag.   My 3in barrel taurus 9mm is a quieter gun to shoot than my 4.5in 9mm Ruger.  I suspect it's because the round isn't breaking the sound barrier out of the short barrel vs the long barrel.   If that's the case,  Subsonic 147gn 9mm should be quieter than screaming 124gn ammo, right? 
What I'm driving at is this:  Does it make more sense to use the slower, heavier round in a home defense situation in order to minimize hearing loss?    Of course the right thing to do is to park a set of muffs on the bed post. 

You'll never notice the sound.

[TSB]

The sonic wave from the escaping combustion gases behind the projectile are traveling at more than the speed of sound in any caliber firearm.  Otherwise, any bullet leaving a muzzle would make no sound at all.  When you here the boom, that's more likely what you hear.  I assume a suppressor, captures those waves of sound and muffles them similar to any muffler design.

Pressure in the chambered casings are enormous, any of you guys who reload are aware of this and carefull not to exceed the recommended pressures.  (I hope)...

[MikeBjerum]

You'll never notice the sound.

That has been my thought as I read this thread.  Not that you want to regularly shoot without protection, the few shots for self protection should do minimal hearing damage.  Or, do you live in an area where you deal with weekly home invasions 

I would worry more about stopping the intruder than a minor hearing loss.  I would compare this thought to thinking if you just drove below thirty miles per hour all the time you would not need to wear seat belts or have an airbag, because at full speed they may break your ribs or nose if you are in an accident.   

Purchase the ammo that will do the job, and hope you never need to use it.