To implement audio in Train Simulator you should start by reading the section on the Blueprint Editor. To create an Audio Blueprint right-click on a folder in the Blueprint Editor, select New Item and then select Sound Blueprint.

It is vital this is set correctly:

Ambient: Any sound which is not part of a Consist or the Rail Network; for example, the sound of church bells placed in the simulation or attached to a church model, environmental sounds, road sounds, factory sounds, birdsong, etc. All sounds set to this type respond to the main audio settings volume slider Ambient Volume.

Cab: For the sounds which you only hear when inside a train cab. Levers, buttons, AWS, etc. These sounds are always disabled when outside the cab view. For Locos with Open backs you may want to include some sounds in a RailVehicle type instead; for example, for loud internal sounds which you expect to also hear externally.

Passenger: The same as Cab but for sounds to be heard only inside Passenger coach internal views.

RailVehicle: All rolling stock sounds other than internal cab sounds - engine, brakes, horns, etc.

The Audio Controls which are referenced in the Sound Blueprint Sound Component is where all the actual sound work is carried out.

There are four types which we recommend you use:

All these Audio Controls are essentially variants on the Generic Audio Control with some specific features, described in following sections.

To create a new audio control:

The Volume variable controls how loud a sound plays back. Train Simulator uses a linear float for Volume ranging from 0 -> 1: a good rule of thumb is that halving a volume value will decrease it by -6dB. So:

It is common to need to use very small fractions ( between 0 -> 0.1) to carefully balance quieter sounds.

The Pitch variable controls the speed or pitch of a sample playback.It has a range from 0 -> 2.

This is where we tell the curve what to act upon to produce the following graph:

So we have created a Volume Curve Modifier which means the X-axis of our graph is volume, and in the controller name, we have typed Minutes_Since_Midnight which becomes our Y-Axis and we reference our earlier created curve Engine Time Volume Curve.

So once this modifier chain is applied to our sound (see Instance Group) the volume of that sound will change depending on the time of day. At midnight (0 minutes) it will play at zero volume, at 1 am (60 minutes) it will play at 0.25 volume, and at 4 pm (960 minutes) it will play at Full volume ('1' volume).

Within a modifier chain, you can have as many volume curves as you like and they all interact together, but they can never push the volume value above 1. Pitch Curve Modifiers work in exactly the same way, but again even with multiple interacting pitch curves, the value can never go outside the limits of the pitch parameter itself.

In the Oneshot section, we have created a Triggered Oneshot. It is similar to the Controlled Loop with the following differences:

It is vital to use this setting when triggering sounds from a value which often fluctuates or changes unpredictably (i.e. some simulation parameters). If this is set to '10' then no matter how much the controller value changes and is valid to trigger a sound, nothing will happen until 10 seconds have passed since the last trigger. This can be used to stop loops juddering on and off when based on a cab lever moving, or can be used to stop hundreds of one-shots being triggered when triggering from a simulation controller value that changes every frame.

Ambient Sounds have a unique Audio Control.

Right-click on a folder, select New Audio Control and select Ambient Audio Control.

The First 4 sections (Sound, Curves, Modifier Chains and Instance Groups) of an Ambient Sound Audio Control work identically as for a Generic Audio Control. However, the Loop and Oneshot sections feature different controls.

There are two types of Ambient Sounds:

Now we need to actually define the curve specified in the image of the modifier chain section, which we called ListenerDistanceSquared Curve.

We suggest you use the following values. With these values, you must use an activation distance of 800 as shown previously and set the Active range start and end values in the ambient loop as 0 -> 2850000. Then in your Sound Blueprint, you can use an Inner Visual Sound Radius of 250 and an Outer Visual Sound Radius of 750.

So the curve values are:

These curve values use an Equal power fade, which means that at the point when you are equally distant from two ambient areas you maintain a constant volume if you used a linear fade then the sound would dip dramatically in the middle of the two ambient areas.

You’ll notice is no value for 0 ListenerDistanceSquared, it is always assumed that the first Y value in a curve will be applied to all X values below the first X value. So the data above would be identical to a data set which starts like the one below:

Ambient Random Oneshots work in pretty much exactly the same way as the Ambient Loop, and should also have the ListenerDistanceSquared modifier chain applied if they are Stereo Sounds. Oneshots are more likely to be mono though, which is the case shown below. In the case of Mono sounds, remember that the Attentuation Start and end distances as described in the Sound section of the Audio Control are once again used. So the lesson here is:

So Ambient Random Oneshots will play random sounds to give you much more variation in your ambient sounds. Using random one-shots in combination with loops will give the most varied and memory efficient solution to ambient sound.

Within a Vehicle Property Blueprint, there is a field where you can specify an audio control which you can link to a Generic Audio Control with a car engine loop.

There is also a section for an Audio Control in the Traffic Controller Blueprint. Here you can set an Audio Control which will provide a constant loop of background traffic for busy roads and also specify the Max Sounds which will determine how many cars you can hear at once on a road, i.e. how many instances of the Audio control referenced in the Vehicle property blueprint are spawned. On very busy roads you could easily spawn hundreds of car sounds if you are not careful with this value and the user's computer will quickly run out of sound channels.

The Bogie Audio Control (Generic Audio Control) is referenced in the Engine or Wagon Blueprint and allows you to add rail joints and flanging sounds.

So to add Rail joint sounds to an engine or wagon. Use the controller JointCount as shown in the image below. The actual distance between joints is set up in the TrackBedRumble blueprint.

The value Curvature in the Controller name parameter returns the value of the current radius of the track you are on. In the form 1/radius. So a track radius of 200 metres is returned as 0.005. Meaning that a curvature of zero is an infinite radius, or in other words straight track. You can then use a modifier chain which is based on the consists AbsoluteSpeed and Curvature to control when the flange sound actually plays.

The Coupling Audio Control (Generic Audio Control) is referenced in the Engine or Wagon Blueprint and allows you to add coupling or decoupling sounds.

Here is an example of a typical TrackBedRumble or Track Sound Blueprint, in this example for a rumble sound you get when you pass over a bridge:

This Blueprint mainly houses references to specific audio controls which are described in following sections, Rumble, Tingle, Junction, Reverb and Derailment.

Ideally, you need to create a new Track Sound Blueprint for each unique track type in the game. The minimum we suggest you need is one for external track and one for tunnel track.

The Distance between Joints (metres) parameter and the Junction clatter distance parameter determine how often and when the joint sounds specified in the Bogies audio control are triggered. Therefore, on a non-welded continuous type rail, you should use a Distance between Joints of zero (no rail joints ever heard) or perhaps a very large value if there are the very occasional joints in the continuous rail (say every 10km). On an older steam route with welded rail, you should use a Distance between Joints value specific to that route. The image above shows a joint distance of 30.

The Category parameter should be set to Exclude from browser list as you will never want to place this blueprint directly in the editor.

The Colour section determines how the particular rumble type will look in the editor. To lay down different rumble types on a piece of track you need to:

The Track Sound Blueprints must be referenced in the Track Blueprint for them to appear in this list. It is also very important that the Default Rumble Blueprint is set in the Track Blueprint before laying ANY track in the editor. Otherwise, you will need to set rumbles for 90% of the laid track manually, which is a long task.

Here is a typical section of a Rumble Audio Control (Generic Audio Control):

The positioning of the rumble sound is handled automatically by the sound engine. The position of the track rumble is snapped to the track, within the length of the player consist and at the nearest point to the 'screen'.

As you can see above, Controlled Loops are the order of the day here. AbsoluteSpeed is the controller which you should use to control the volume of the rumble based upon speed, via a curve and modifier chain. The recommended start value is 0.05. This means the rumble will not play whilst the train is stationary and will negate any slight 'flutter' of the AbsoluteSpeed value whilst the train is stationary.

Tingle is used to control two effects in Train Simulator, although a whole range of potential effects is possible.

The tingle effect is the sound of the rail vibrating as a train is approaching. This is controlled again via the AbsoluteSpeed controller but also via the controller DistanceToConsist which is the distance to the nearest point of the consist in question.

A sound of rushing air as a train passes is the second sound. It is essentially identical to the DistanceToConsist controller except when in use on a player consist it will return a value of zero when in any camera mode where you are attached to the consist.

Junction sounds can be added using the SwitchingProgress controller which changes smoothly between 0-1.

There are three controllers which are used to create refuelling sounds:

These generic audio controls are added as a child to the relevant track furniture object.

Traversers and Turntables work simply with a controller that is based on the name of the animation which controls them. So, in this case, we are using a controller called AnimationTime_Rotate, as the Turntable object is animated using a file called Rotate.ia

If the animation was called for example Turntable.ia then a controller would automatically be created called AnimationTime_Turntable.

AnimationTime controllers are in seconds. If you just want to trigger a loop while an animation is moving (as in the case of a turntable like above) then you can just use 'Value is changing'. If you want to trigger sounds only at a particular point in the loop then just use the timing in seconds of where it occurs in the animation, sometimes it’s easiest to get the animator to provide you with relevant timings.

Locomotive audio is certainly the most important area of sound design in Train Simulator, if you’ve got this in the document then you will already have picked up the necessary skills to start creating engine and wagon audio controls. This is not the point to dive straight in though!

Below are lists of relevant controllers for use in the different engine types. All rolling stock will also inherit any controllers of the AnimationTime type as described in the Traversers and Turntables (external link) section and also any 'controls' which have been set up in the Engine Blueprint.

The Steam Audio control also contains a unique section which is used to trigger steam exhausts (chuffs) and any regular mechanical type sounds which are based on the rotation of the main driving wheels.

It is vital that the two parameters Drive wheel diameter and Number of Cylinders are set correctly in order to have the correct number of chuffs per drive wheel rotation.

The Steam Audio control has a unique Exhaust section which is essentially a one-shot controller.

To add chuff sounds, insert a Steam Exhaust element into the Exhaust section. Use AbsoluteSpeed as the controller with a valid start and end value. This way you can use various sets of chuffs of shorter lengths for different train speeds.

If you add one Steam Exhaust Element called 1 then everytime a chuff is triggered you will trigger 1, 1, 1, 1, 1, 1, etc.

If you add three Steam Exhaust Elements called 1, 2 and 3 then everytime a chuff is triggered you will trigger a repeating sequence of 1, 2, 3, 1, 2, 3, 1, 2, 3. Of course, each sound referenced in here could also be a random one-shot to add variation.

It is best to do the horn/whistle as a separate sound child of the engine for two reasons:

The horn relies on a control being created, which in this case was called simply Horn in the Engine Blueprint.

Animated scenery works exactly the same as described in Traversers & Turntables, using the controller AnimationTime_AnimationName (do not include the .ia extension).

These are objects such as the Digger and Forklift in Train Simulator which were placed directly in the world. The Audio blueprint must be added as a child to the object.

The Weather Audio Control is referenced directly from the Weather Pattern Blueprint.

There are 5 controllers with which to control weather sounds:

If you want the rain sound to change loop as the RainDensity increases then you need to create various modifier curves to crossfade between different loops.