diff --git a/src/Audio/SourceVoice.cs b/src/Audio/SourceVoice.cs
index b970051..e650b5b 100644
--- a/src/Audio/SourceVoice.cs
+++ b/src/Audio/SourceVoice.cs
@@ -139,6 +139,11 @@ namespace MoonWorks.Audio
 			Submit(buffer.ToFAudioBuffer());
 		}
 
+		/// <summary>
+		/// Calculates positional sound. This must be called continuously to update positional sound.
+		/// </summary>
+		/// <param name="listener"></param>
+		/// <param name="emitter"></param>
 		public unsafe void Apply3D(AudioListener listener, AudioEmitter emitter)
 		{
 			Is3D = true;