## Sound of the rails. How to simulate?

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### Sound of the rails. How to simulate?

Here is the video: https://youtu.be/wB5NCKQWY40?t=2m3s
Maybe someone knows, what is the nature of that sound on 2:10?
How can we simulate it in SunVox?
I don't understand the physics of this process. Seems that the delay of each frequency is equal to 1/freq, or something like this...
Actually we can hear the similar sounds during the glacial melt, or by kicking the metal rope.

Koekepan
Posts: 237
Joined: Thu Dec 05, 2013 4:56 am

### Re: Sound of the rails. How to simulate?

My current best guess:

A broad spectrum sound, the high parts of which die out before the longer frequencies, timbrally affected by the medium through which it moves (i.e. the rails).

The origin of the sound is train wheels rubbing against, and striking imperfections in the rails.

The sound is transmitted forward much faster than the train travels, and quite effectively in the stiff (but elastic) medium of the steel rails. These vibrate, transmitting their sound to the air but modified in a metallophone-like way, the same way a glockenspiel's tone is different from that of the moment that the hammer strikes it.

The rail is not an unbiased bearer of sound, but changes tone rather the way a bell or tom does, over the course of its ringing, biasing it to deliver the high sounds first, leaving it with low tones afterwards.

Another possible original impulse might be secondary from the wheels on the rails, if one rail rubs against another, end-to-end as they move while the train rides on them. In any case, you're looking at stiff but basically elastic sound media, losing the high frequency tremble before the lower frequency wobble.

FreeFull
Posts: 41
Joined: Fri Dec 10, 2010 11:42 am

### Re: Sound of the rails. How to simulate?

The original impulse would be from the wheels moving over the gaps between the rails, I would think. The gaps exist to make room for thermal expansion.