diff --git a/BizHawk.Emulation/Interfaces/IEmulator.cs b/BizHawk.Emulation/Interfaces/IEmulator.cs
index 3365febc56..423956fc0e 100644
--- a/BizHawk.Emulation/Interfaces/IEmulator.cs
+++ b/BizHawk.Emulation/Interfaces/IEmulator.cs
@@ -7,17 +7,26 @@ namespace BizHawk
 	public interface IEmulator : IDisposable
 	{
 		IVideoProvider VideoProvider { get; }
+		/// <summary>
+		/// sound provider for async operation.  this is optional, and is only required after StartAsyncSound() is called and returns true
+		/// </summary>
 		ISoundProvider SoundProvider { get; }
+		/// <summary>
+		/// sound provider for sync operation.  this is manditory
+		/// </summary>
 		ISyncSoundProvider SyncSoundProvider { get; }
-		/// <summary></summary>
-		/// <returns>false if core doesn't support async sound</returns>
+		/// <summary>start async operation.  (on construct, sync operation is assumed).</summary>
+		/// <returns>false if core doesn't support async sound; SyncSoundProvider will continue to be used in that case</returns>
 		bool StartAsyncSound();
+		/// <summary>
+		/// end async operation, returning to sync operation.  after this, all sound requests will go to the SyncSoundProvider
+		/// </summary>
 		void EndAsyncSound();
 
 		ControllerDefinition ControllerDefinition { get; }
 		IController Controller { get; set; }
 
-		// note that most cores expect you to call SoundProvider.GetSamples() after each FrameAdvance()
+		// note that some? cores expect you to call SoundProvider.GetSamples() after each FrameAdvance()
 		// please do this, even when rendersound = false
 		void FrameAdvance(bool render, bool rendersound = true);
 
diff --git a/BizHawk.Emulation/Interfaces/ISyncSoundProvider.cs b/BizHawk.Emulation/Interfaces/ISyncSoundProvider.cs
index c74c14c172..4e29a0ec5d 100644
--- a/BizHawk.Emulation/Interfaces/ISyncSoundProvider.cs
+++ b/BizHawk.Emulation/Interfaces/ISyncSoundProvider.cs
@@ -14,6 +14,9 @@
 		void DiscardSamples();
 	}
 
+	/// <summary>
+	/// wraps an ISyncSoundProvider around an ISoundProvider
+	/// </summary>
 	public class FakeSyncSound : ISyncSoundProvider
 	{
 		ISoundProvider source;
@@ -22,7 +25,7 @@
 		/// 
 		/// </summary>
 		/// <param name="source"></param>
-		/// <param name="spf">number of sample pairs to request for each call</param>
+		/// <param name="spf">number of sample pairs to request and provide on each GetSamples() call</param>
 		public FakeSyncSound(ISoundProvider source, int spf)
 		{
 			this.source = source;