UDK Attenuation Radius

Attenuation radius is an important factor when dealing with sound in UDK. This allows us to set up the distance in which the sound is heard at. This is done very simply. 

To modify your attenuation radius, drag the sound file into your scene. When you do this, you'll notice, it is encompassed by circles. This is the attenuation radius. Whatever is outside of this attenuation radius is unaffected by sound, thus is will not be heard in these areas.

Double click on the speaker icon in your UDK level, and you should be presented with a small window. 

The top attribute should be labeled, Ambient Sound Simple. If you then click the down button, you'll be presented with the Ambient Properties tab. Once you're here, you'll need to click the down arrow on this, and all of the properties should be revealed to you. Simply open the attenuation tab and make sure attenuation is clicked on. Then, you can modify the values of the radius min and max to suit your needs. When you do this, you'll notice that the circles around the speaker change size.