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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.

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.

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.

Koekepan wrote: ↑Wed Mar 09, 2016 9:06 pm In any case, you're looking at stiff but basically elastic sound media, losing the high frequency tremble before the lower frequency wobble.

I think this is correct. The rails behave as what is known as a dispersive transmission or dispersive delay line.

I recently composed a piece in which I wanted to feature the sounds of impacts and cracking of an ice sheet over a body of water. It turns out that such ice sheets are also an acoustically dispersive medium. Even more interestingly because it is a sheet, it does this in all directions (including if the ice is thick enough for the effect to become apparent, throughout the thickness of the ice).

After listening to some of the audio clips I found:

https://silentlistening.wordpress.com/2 ... ce-sheets/
https://freesound.org/people/Angel_Pere ... nds/47201/

I came up with the metamodules in the attached project:
Dispersive_01 attempts to synthesise the sounds of an impact followed by dispersive effects.
Dispersive_02 and Dispersive_02_audio_ip uses a more complex metamodule that attempts simulate the behaviour of a dispersive delay line. There are a number of parameters controlled by suitably named MultiCtl modules that allow the sound to be adjusted.

Try selecting a module and playing a few notes.

Something that would be fun but is not yet implemented would be to make the frequency intervals of the filters controllable possibly even by the pitch of a notes played from a keyboard or a pattern.

These effects can be heard during the first piece "Summit to Sea Level: An Alaskan Elegy" in the video in this post in the SunVox FB forum:

https://m.facebook.com/groups/sunvox/pe ... jJN6C6B-gA

signality wrote: ↑Thu Nov 30, 2023 3:25 am I came up with the metamodules in the attached project:

Very cool! Thank you!