# Documentation/Engine/Sound/TruckEngine

### Sounds - Truck Engine

The sound of the truck engine is very specific kind of the sounds.
Engine sound is very sensitive to be balanced between sound sources.

So there are a few rules for the engine sound:

• The each sound of the truck engine should be in the separate sound bank.
• There are only the four events and all should be implemented in the same bank.
• It is not recommended to combine events of different banks for the engine sound.

## Engine Sound Events

• All events should be at the folder "engine" in the events browser.
• This events should exist in the bank:
engine/engine
engine/exhaust
engine/turbo (from 1.39)

### Event "engine"

Event "engine" plays sound of the engine.
It has to be 3D event. The event should be routed to the "truck_engine" audio bus.
The event must be looped and its living cycle is controlled by "play" parameter (see bellow).

These event parameters must exist:

• engine/play
The parameter "play" control living cycle of the event:
value play = 1 means - sound is playing
value play = 0 means - sound should be stopped
• engine/brake
the value is in the range <0 - 1> and represents the action of the motor brake
the value is in the range <0 - 1>
value < 0.05 means idle engine sound
• engine/rpm
the value is in the range <0 - 3000>
the value represents the number of engine revs per second

### Event "exhaust"

Event "exhaust" plays sound of the exhaust.
It has to be 3D event. The event should be routed to the "truck_exhaust" audio bus.
The event must be looped and its living cycle is controlled by "play" parameter.

These event parameters must exist:

• exhaust/play
• exhaust/rpm

The purpose of the parameters is the same as for the "engine" event (see Event "engine").

### Event "turbo"

Event "turbo" plays sound of the turbo.
It has to be 3D event. The event should be routed to the "truck_turbo" audio bus.
The event must be looped and its living cycle is controlled by "play" parameter.

These event parameters must exist:

• engine/turbo
the value is in the range <0 - 1> and represents the action of the turbo system

Event "start_bad" plays sound of unsuccessful starting of the engine.
It has to be 3D event. The event should be routed to the "truck_engine" audio bus.
The event is one-shot sound (without loop).
There are no other parameters for the event.
It is possible to use randomization of the assets supported by FMOD Studio.

## Engine Sound Configuration

The sound configuration of the engine sounds is stored in the "accessory_engine_data" data.
There is array "sounds" which contents specification for the mandatory events of the engine.
That means that each type of the engine can have assigned its own sound bank.

Example:
There are configuration files of engines for the "Peterbilt 579" at the folder "\def\vehicle\truck\peterbilt.579\engine".
Each engine include @include "sound.sui" file which contents indirect definition of the events:

	sounds: 4
sounds[]: "engine|/def/vehicle/truck/peterbilt.579/engine/sound_engine.soundref"
sounds[]: "exhaust|/def/vehicle/truck/peterbilt.579/engine/sound_exhaust.soundref"
sounds[]: "turbo|/def/vehicle/truck/peterbilt.579/engine/sound_turbo.soundref"


There are .soundref file (for each event) to specify bank end FMOD event of the sound.

Content of the sound_engine.soundref is:

source="/sound/truck/peterbilt_579.bank#engine/engine"


The record
sound: "/sound/truck/peterbilt_579.bank"
at the any engine configuration file assigns the sound bank to the engine.

## Engine Sound Position

The 3D position of the engine sound is (by default) 1 m above the first axle of the truck.
This position could be modified by the .soundref file. (see Sound reference file)