What makes you think you did there?
Exactly. I know you'll have a wealth of experience in this area, but I at least have some limited experience of being in/around small-arms fire, rifle/LMG fire, and a variety of heavier ordnance - as well as having been some 500m from a large car bomb in the middle east. And, as you say, it really doesn't sound like the movies. To me, small-arms fire sounded almost like pop guns, rifle/LMG sounded like loud pop guns (unless you're near the receiving end, when all you hear is the small crackle of the bullet's miniature sonic boom, followed by the muffled thud of the powder explosion catching up. And a fairly sizeable car bomb is, in my own case at least, experienced more than it's simply heard or seen. The initial visual registration is followed almost immediately by the shockwave, which is an incredible visceral (but noiseless) thump that jolts the whole body. Then there's the rush of explosive wind, and finally the dull thud of the explosion itself. It's
so unlike it's portrayed in almost every movie or TV show*.
So yes, even if the passengers on the Estonia
thought they knew what an explosion on a ship, or two ships colliding, might sound like, the very high probability is that they did not. The sounds they heard are valid evidence, as are the sounds from their own personal experience to which they likened the noises. However, their inferences as to what actually caused the noises within the ship that night have little or no evidential value.
* Funnily enough, I was talking about exactly this, a dozen or so years ago, with someone I knew (through a mutual friend) who worked at Pinewood Studios. And she said that film and TV studios have understood for a very long time now that what they depict on screen isn't realistic - but they continue with the misrepresentation because this is what audiences are now conditioned to think they look/sound like (and if they did accurate depictions, audiences would simply think they'd screwed it up). As another part of this, they also kept/keep showing people being thrown violently backwards if they're shot with a handgun/rifle - whereas in reality, even a direct hit to the torso from an AK-47 at close range will just make the victim crumple and fall to the floor on the spot.
ETA: Hoooo man, National Geographic channel is showing the first episode of its 4-night documentary about 9/11 in the UK right now. It's gut-wrenchingly powerful viewing (not sure if they've started showing it in the US yet). Try to catch it if you can.