Layers Of Sound

One design aim of the sound code was to allow multiple “layers of sound” to be produced simulating the complex ways real sound varies.

This example defines some ways of applying multiple sound streams to a loco to get complex sound.

You need a sound enabled version of Rail3D, build 102.3.0.8 or later for the effects described here.

You will probably also find it helpful to try out each stream on its own, as when they are all playing at once it is hard to distinguish one effect from the other

The model

My example loco is the Swiss, mbg hge44/2 electric loco, and just to make things more challenging this loco can operate in bot hrack and adhesion modes.

Locomotive Noise

The first sound stream I want is the locomotive noise - ie the noise produced when under power. This, fairly obviously is related to the engine power controller, so my first sound stream looks like this:

  
    Power
    Swiss\HGE442.
    7
    Speed

This sound scheme uses the two channel power scheme and the hge442 set of waves (waves 0–6).

This will produce increasing levels of power noise as the loco applies power.

Track Noise

The above is all very well, but means that when coasting down hill the loco makes virtually no sound, so I need a second sound stream to produce noise related to track speed:

  
    Speed
      Swiss\HGE442S.
      7
    Speed

This uses the simple two channel speed scheme with waves hge442S (waves 0–6).

One challenge is to find suitable sound sources for the above two schemes. Obviously a real recording will include both sound sources - motor noise and track noise - so we need to find a suitable bit of recording where the motor noise dominates for stream1 and where track/wheel noise dominates for stream2. And of course we need to do this over the whole range of power and speed variation. I managed to find suitable bits of recording where the motor dominated, and suitable bits (mostly going down hill) where the trakc noise dominated. There not completly “pure” sounds, but in practice this doesn’t matter.

Tunnels and bridges

Another significant effect is that the noise will change when the loco goes into a tunnel, fortunatly we don’t need to worry about that as Rail3D handles it automatically. When riding in the cab of a loco, the first sound stream is multiplied when the loco is in a tunnel (track set to dark) to produce the effect of the noise reverberating off the tunnel walls.

Flange squeal

The next noise I am concerned about is the wheel flange squeal on tight corners. To model this I need to add another sound stream for the wheel squeal:

  
    Squeal
    Swiss\HGE442 SQ

There’s only one wave used here, so I don’t need a number of waves statement.

nb this stream scheme is not working properly yet and needs some more work

The Rack.

As mentioned above, the hge44/2 is a rack and adhesion loco and thus there are some changes needed to the sound effects:

Track noise is different on the rack to on ordinary track
There is a distinct ‘thump’ as the rack engages.

Rail3D can handle this with a modified version of the Speed scheme for rack/adhesion locos:


    Speed_RA
    
      Swiss\HGE442S.
      7
    
    
      Swiss\HGE442R.
      7
      Swiss\HGE442 JR
    
    Speed

This is a speed based scheme, except that:

There are two sets of waves defined, one for rack mode and one for adhesion.
There is a “Rack NoiseRack Noise” parameter which defines a single shot wave to be played when joining the rack.

So with this definition, Rail3D will use the hge442S wave set on normal track, but when the loco joins a rack section, there will be a one off “hge442 jr” (the “thump”) and then Rail3D will play the hge442R set while the loco is on the rack.

Full definition

The full sound definition for this loco is:


  
    Power
    Swiss\HGE442.
    7
  

  
    Speed_RA
    
      Swiss\HGE442S.
      7
    
    
      Swiss\HGE442R.
      7
      Swiss\HGE442 JR
    
    Speed
  

  
    Squeal
    Swiss\HGE442 SQ
  

  Swiss\HGE442_Whistle

import

Rail3D*