But have you ever actually DONE it? Had your instructors? It’s 1 thing to teach the techniques, it’s another to deal with the actual results, and unless you’ve been there at least as a witness, you have no idea what really goes on.
There are 2 ways to the heart: through the ribs or down the throat. If you go through the ribs, you’ll find that the chest cavity is like a drum, a hollow cylinder full of air. Hitting this hard enough to penetrate the ribs and intercostal cartilage makes a highly noticeable THUMP (as does stabbing into the skull). You can’t feel around on the victim to find a gap in the ribs, and the gaps are full of tough cartilage anyway, so even with a sharp point you still have to hit hard to get in deep enough, through whatever stands in the way at the random point of impact. Then your fist slams into the guy’s chest making the “drum” thump. Going through the ribs also means the blow compresses the chest in the way it naturally flexes, so you push some air out besides making the drum sound. Because your knife is blocking the hole it made coming in, most of this air takes the path of least resistance and goes up the throat past the vocal cords. So you also get a fairly noticeable “OOF” from the victim.
The other way to the heart is down through the base of the throat. This avoids the chgest drumming and chest compression but can only be done if the victim’s chin is out of the way. This really isn’t possible against sleepers–the victim has to be standing up. So you basically must tackle him from behind, snatch his head back over your shoulder to expose his throat, then stab. This “tackle” makes the usual scuffling sounds and it lasts 1/2 a second or so before you strike, which is enough time for the victim to start to scream. And it’s quite difficult in practice totally to seal off both the mouth and nose during this quick, blind grab, so usually there’s at least some muffled cry of surprise.
Either way, you’ve killed the guy, but it isn’t instant. There’s still a second or 2 of adrenaline-fueled consciousness before his lights go out. During this time, he will thrash and try to scream, which makes a varying amount of noise depending on what’s around for him to kick, whether or not his vocal cords still work, and how much air he can gurgle out the hole. And if he was holding something, he’s going to drop it somewhere in this process.
I had a great uncle in the Foreign Legion in WW1 myself, and he told the same story about killing 1 guy so the other would wake up to find him. He also said this was BS. They killed everybody, naturally enough, because that was there job. They only told these stories to build their reputation with both friend and foe.
There ain’t no silent kills. Stories otherwise are legend and Hollywood.
