This defines the curve type of the different custom curves that can be queried and set within the AudioSource.
The AudioSource can hold a number of custom distance curves, this enum is used within the AudioSource API to differentiate between them.
| CustomRolloff | Custom Volume Rolloff. | 
| SpatialBlend | The Spatial Blend. | 
| ReverbZoneMix | Reverb Zone Mix. | 
| Spread | The 3D Spread. |