[Leif...]

Would the fact that sounds travel faster in water then air mean that if you’re standing on the bridge when a torpedo hits a ship you would in fact hear two impact sounds?

First the one travelling in the water hitting your sub and then the normal impact sound travailing in the air? Or would you not hear the water bound sound when it hits the sub?

Leif…

[Gollard]

Hi Leif,


Im not a hundred percent sure if I can answer this question, But I dont think you would be able to hear the sound for the water impact, not unless you were a dolphin or a whale only joking he he he.

Sorry I couldnt resist replying with the above thread

[Teemu]

Yes, you could hear the impact sound transmitted through water. The sound would also have to travel through the hull of your boat to reach you on the bridge, and you would hear a faint, low rumble. Depending on various factors, of course.

Sound travels incredible well in sea water - I remember reading of communication based on under-water explosions, it was estimated the sound could travel up to 10000 kilometers (poor fish). It would take two hours for the booms to reach there!

[Etienne]

Indeed, sound travels well in water. The Kursk explosion was heard by hydrophones in Alert, Nunavut... Althought the great circle route might actually be pretty short, it's still a good way.

I don't know, however, if you'd hear both sounds, or if the difference in time between the end of the underwater boom and the beginning of the air boom would be enough to be differenciated...

I'll do the calculations on a day without physics and positionning exam.

'tienne

[NeonSamurai]

With out doing any calculations i would guess that at normal surface firing ranges for torpedoes that the sound from the surface and sea would reach the boat at almost the same time (you would probably hear the first part of the underwater explosion, then hear the surface explosion) at the farther distances.

[bart]

Hang on and I'll just try it, fingers in ears everyone, except me of
course

[Etienne]

Using standardized values (Well, the ones we use in class, anyway), and assuming a distance of 5 NM, the airborne sound wave would reach you 21 seconds after the underwater waves. That is, the underwater sound wave would reach yu 6,17 seconds after the explosion, while the airborne would get to you after 27,23s.

I think. (I used 1500 m/s for the underwater wave, and 340 m/s for the airborne sound wave) 27 seconds sound long to me, but hey, sound's slow.

This means that if the explosion sound is 30 seconds long, it'll just sound like a long rumble.

At a more realistic - For Silent Hunter, anyway - distance of 700m, the differences falls to 1,59s, which wouldn't make for a noticeable difference, I believe.

'tienne

[Leif...]

I tried it in my own sim. The sound effect is just something I found on the net and is not really appropriate. Also I play the same effect twice without changing the volume or anything as I’m only interested in the delay at the moment. Anyhow it’s very noticeable even at short ranges as this little clip might show you.
http://w1.510.telia.com/~u51008935/temp/soundtest.avi

Leif…

hm strange, when I tried the clip at work the movie stops exactly when the torpedo hits the ship and the water cascade are about to erupt. Weird.

[NeonSamurai]

Did you guys remember to calculate how long the water sound would take to travel thru the sub and reach the persons ears?

Sound and how you hear it can do some funny things too, like for example sound waves bouncing off of objects (like water, coasts, other ships, bottom of the ocean, sea gulls, etc.) can make the sound seem alot longer in duration then it actualy is. Like if you have ever heard an explosion in real life or even blasting footage, the sound can last for a few seconds even though the single explosion itself took 0.5 seconds roughly.