1. pirate1802
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    pirate1802 Member

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    can a person 'hear' a bullet coming at him?

    Discussion in 'Research' started by pirate1802, May 30, 2014.

    Suppose this person is extremely perceptive, but still a normal person, no spidey sense. No Jason Bourne-like abilities either. So, heightened-but-within-the-realistic-bracket senses. How realistic is it for him or her to hear a faint ..something that alerts him of the danger? Hollywood movies show bullets speeding at you with a buzzing sound, but we all know Hollywood is to realism what North Korea is to democracy. So I'd like to hear what people who are more knowledgeable than me has to say of this issue.

    Thanks. :D
     
  2. Komposten
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    Komposten Insanitary pile of rotten fruit Staff Supporter Contributor

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    I believe most modern guns fire bullets at more than 400 m/s, the speed of sound is about 340 m/s. This means that the bullet will travel faster than any sound it would make, and therefore I'd say it is completely impossible to hear a bullet before it hits or passes you (I disregarded the air resistance here, in reality the bullet slows down quite fast).

    Though I have no idea if it the bullet gives off any sound (which would reach you sometime after the bullet). If it does, you could always go with a gun whose bullets go slower than 340 m/s or have a distance between shooter and target during which the bullet has time to slow down (though those bullets would have to move very slowly to allow a human to react to the sound before it is too late anyway).

    Edit:
    I did some quick calculations. If a bullet moves at a constant 170 m/s (pretty slow, half the speed of sound) any sound it might give off would reach a target at 100 meters distance 0,3 seconds before the bullet. Not much time to act.
     
    Last edited: May 30, 2014
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  3. pirate1802
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    pirate1802 Member

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    I see, so you basically have to be Bourne to escape death like that. Although I planned this action to involve a sniper shooting at the said person from quite a distance away. Still, point taken.

    Maybe I'll have him spot the light glinting off the shooter's scope or something. :D
     
  4. Lemex
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    Lemex That's Lord Lemex to you. Contributor

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    You can feel a bullet pass by you, you do sort of hear it if it passes close past your ear - it depends on the circumstance. The thing you are bound to hear, though, is the pik of the bullet slamming into a nearby wall.
     
    Last edited: May 30, 2014
  5. Komposten
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    Komposten Insanitary pile of rotten fruit Staff Supporter Contributor

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    Unless the bullet passed through the acoustic center of your brain along the way towards said wall. ;)
     
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  6. KaTrian
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    KaTrian A foolish little beast. Staff Supporter Contributor

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    Maybe some X-men type of mutant could?

    I think in real life it's pretty much bang and ow at the same time, I mean, when looking from our slow human perspective.

    If there's a lot of distance, as is the case here, I seriously doubt you could hear it, unless you're wearing some badass hearing-enhancers. And in any case, you wouldn't have time to react even if you heard it. I'm not a soldier or anything, but I've shot firearms and watched videos of people shooting targets, so I'm basing my assumption on that.

    Snipers try to conceal their equipment, of course, but I don't think it's unheard-of to catch a glimpse of reflection. Anti-snipers might look for muzzle flashes; like they try to lure the guy out by making them react and shoot, then they mark the flash, and get ready to take the sniper down. But I guess that's not relevant for your story here.
     
  7. Lemex
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    Lemex That's Lord Lemex to you. Contributor

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    To be honest, I was speaking from experience. It happened while I was on holiday in a then volatile country and I just happened to drive into a gun fight, so I'm glad said bullet didn't slam into my brain. ;)
     
  8. KaTrian
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    KaTrian A foolish little beast. Staff Supporter Contributor

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    Yikes! Good thing luck was on your side.

    I've noticed this is something that is often described in action novels: the protag feels or "hears" the bullet whip/zip past. Fictional novels by ex military ops are my guilty pleasure, and even though they're fiction, this is something that's often mentioned. I suppose those ops often write from their own experiences, so it seems like a plausible detail.
     
  9. Lemex
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    Lemex That's Lord Lemex to you. Contributor

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    It's apparently quite common. I remember reading Christopher Hitchens' memoirs, and he details a similar experience he had when he was in Kosovo. Considering an assault rifle like the AK-47 fires hundreds of bullets per minute, and if you are hit you are not going to remember much, it's hardly surprising there are so many near-misses, even if its a stray bullet like I think my experience was. I don't think I was being shot at.

    In regards to the OP's question: my grandfather, who was an officer in the British army during the dying British colonial period and WW2, used to have a saying: 'You don't hear the bullet that kills you', and that might be true, but you sure do hear the bullet that almost kills you, and you remember it too.
     
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  10. KaTrian
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    KaTrian A foolish little beast. Staff Supporter Contributor

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    I remember reading from somewhere a mention of a sensation of heat as well, but again, I haven't any personal experience here, thankfully.

    Sounds like an awfully realistic saying.
     
  11. Lemex
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    Lemex That's Lord Lemex to you. Contributor

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    I didn't get that, I got an adrenaline rush, and a cold rush of fear.

    It happened in Turkey, near the boarder with Syria. I traveled a lot, across the Mediterranean, in my teens (it's where my obsession with the Classics comes from) and saw a lot of beauty, but I saw a lot of really horrible things too.
     
  12. Bryan Romer
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    Bryan Romer Contributing Member Contributor

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    There may be other sounds from the weapon just before it fires which just might be heard with exceptional hearing and the right conditions - no ambient noise, or wind etc. Some sniper rifles are bolt action weapons. If the sniper is careless, the click of the bolt locking in place might be audible. Or the assassin might have made a noise while shifting into firing position.

    Most silenced assassination weapons use subsonic ammunition, so even the "crack" of the bullet would not be there.

    You won't hear the bullet, but even with a suppressor the explosion of the round makes a pretty loud noise. A subsonic bullet is by definition slower than sound, so if the MC has exceptional reflexes as well as hearing he might just begin to move in time to save his life. Note that the average reaction time of a human being to unexpected events is around 1.5 seconds - a pretty long time when you are racing a bullet.
     
  13. lostinwebspace
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    lostinwebspace Active Member

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    I agree with @KaTrian. Unless you're Spider-Man, bang and ow at the same time.
     
  14. Garball
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    Garball Sometimes nothing can be a real cool hand. Supporter Contributor

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    In Black Hawk Down, the troops are told to not hug the walls because bullets will "walk" down them and a ricochet is a good sound to hear. The bad sound is the small sonic boom "pop" as a bullet whizzes past your ear.

    I saw an account of a sniper using a .50 cal on a human target at a very long distance. I can't remember if the bullet slowed down so much that the target heard the recoil or saw the muzzle flash, but the sniper remembered seeing the facial expression of his target change.
     
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  15. A.J. Pruitt
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    A.J. Pruitt Member

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    The very best source to find out if a person can hear a bullet before it hits him, is an ex-military soldier who has been in combat in Vietnam or Iraq. I have been told that, sometimes, the victim has heard the bullet when it impacts their own body, but the shock of the impact eliminated their sense of hearing so they didn't hear the sound of the rifle shot. I have been told by other veterans that they heard the flat thud of a bullet hitting a fellow commrad; however, in a military gun battle, there is so much noise that it would be impossible to hear the sound of the rifle that sent the bullet.

    I have also been told that at times, the victim who had been hit with a bullet, had the sensation that the ground came up and hit him or her in their face. They had no sensation of being hit with a bullet. I have been told by some wounded veterans that when hit, they couldn't figure out why they were running forward; then, finding themselves laying on the ground. They hadn't even felt or heard the impact of the bullet hitting them.

    Just find a veteran of Iraq or Vietnam. Some of their first hand experiences are almost non-believable but are true.
     
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  16. archerfenris
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    archerfenris Active Member

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    I've never been personally shot at with direct fire (as in a bullet from a rifle/pistol) like Lemex has but I have been shot at with rockets, mortars, and recoilless rifles (think bazooka) aimed into the sky. During my time in Afghanistan the Taliban would fire off about a rocket a day, sometimes five times a day during the fighting season. These usually impacted in the middle of our Forward Operating Base because the insurgents were very good at it and had a large, six mile wide target to aim at. This, unfortunately, was were I worked, smack in the middle of the camp.

    A rocket/artillery round/mortar/etc, similar to a bullet, will make the large explosion sound (bang) when exiting the tube after rear obturation forces it out. It does make a sound as it flies through the air. Personally, my experience was I COULD hear it just a second or so before it impacted. A rocket makes a sort of wobbling sound and the mortars/recoilless rifle rounds make the well known whistling sound. However, I was never actually hit by any of these (obviously). The closest I ever came was about 100 meters from a rocket hitting, which scared me enough as is. Other soldiers I talked to while there, though, told me that what I was hearing was the rocket/mortar flying OVER me. The general consensus among the veterans there (those that had been shot at before) was that if you hear the whistle you're good. Those that are hit by the rocket never hear it coming. This, however, conflicts with what I've seen personally. I was watching on one of our video feeds when we fired two "smart" mortar rounds at two insurgents attempting to fire a recoilless rifle at the base (I think they were having a malfunction with their weapon). The first round never exploded. We actually were afraid someone had miscalculated and fired the round hundreds of meters off, but actually the round was a dud. So much for smart. The men visibly ducked, took cover, then ran like maniacs. They escaped before the second round impacted directly on their old position. I do know enough about artillery and rockets to say that these rounds probably are slow enough to hear just before they impact. A bullet, I assume, travels at too great a velocity.

    I talked to a lot of soldiers while I was there. One was my guard at night who was put on guard duty (guarding me from those untrustworthy Afghan soldiers) for some type of behavioral misconduct. He'd been in several firefights in one of the deadliest region of Afghanistan. He told me that you can hear bullets passing overhead. They apparently whistle/hiss if they're far awayish (feet over your head) and start cracking when they're going inches over your head. However, you can only hear them as/after they've passed. A man who is shot by a sniper firing a mile away will hit the ground before anyone hears a gunshot.

    So no. He wouldn't be able to hear it. And after they've been shot at, unless they're a war veteran, they'll probably have no idea what is going on.
     
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  17. archerfenris
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    archerfenris Active Member

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    And as far as what Garball said about bullets sliding along walls this is true. I've seen machineguns firing at night and the tracers let you see all the crazy things that bullets do. They hit the ground and fly up, they ricochet, snake, etc.

    If the velocity of the round is low enough. A ricochet for example, a bullet could be heard as well.

    You can see evidence of both of these here. If you watch closely you'll see the bullet ricochet off the ground and hit the guy's head gear. Preceded by the whistle of the round.

     
  18. Nothingness
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    Nothingness Active Member

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    Since a bullet travel's faster than the speed of sound the bullet will hit its target before the sound.

    Silencers slow down the bullet bellow the speed of sound (to avoid the sonic boom) but they also make a lot less noise. But they're still going fast (I have no ideia how much).

    People still need time to react, a normal reaction would be maybe 0,4s (some of that time is used by the brain to interpret the message, some for it to create the reacting message).

    It would have to be pretty far away, still be noisy somehow, for a character to know it's coming, and even further for him to react.
     
  19. Michael the Angel
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    Michael the Angel Member

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    When I was in the service and I had to react to fire, the bullet would always hit, then you'd hear the shot. It doesn't matter how far away or how close they are. Sound is influenced by wind speed, relative humidity, and distance to the audience. A sniper's round actually hits almost a full second before a retort is heard, in most cases that I personally witnessed. The closer they are, the closer the timing will be between the round hitting it's target and the sound of the propulsion system.

    Your hero would have to be tipped off by visual cue if they were a normal person. Like by, let's say, the muzzle flash. You see the flash, the bullet lands, you hear the sound. That is ALWAYS the order of operations.
     
  20. Mans
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    Mans Contributing Member

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    No, the speed of bullet is more than the speed of moving sound in the air. Therefore, the person can only hear the sound of a bullet that is dead or injured.
     
  21. KeriLynn
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    KeriLynn Member

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    Normally by the time the gun is fired by the time you hear the bullet it's to late to dodge it. Now if you're say 2 feet from the person you'll hear the gun go off but you won't necessarily know it's fired at you or which direction it was even fired in.
     

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