Sets the minimal distance if this is a 3D sound. Specify the distances at which 3D sounds stop getting louder or quieter. This works like this: As a listener approaches a 3D sound source, the sound gets louder. Past a certain point, it is not reasonable for the volume to continue to increase. Either the maximum (zero) has been reached, or the nature of the sound source imposes a logical limit. This is the minimum distance for the sound source. Similarly, the maximum distance for a sound source is the distance beyond which the sound does not get any quieter. The default minimum distance is 1, the default max distance is a huge number nearly to infinite.