diff --git a/public/engine/IEngineSound.h b/public/engine/IEngineSound.h
index 25bcef2b..5578de1c 100644
--- a/public/engine/IEngineSound.h
+++ b/public/engine/IEngineSound.h
@@ -72,11 +72,11 @@ public:
 	// NOTE: setting iEntIndex to -1 will cause the sound to be emitted from the local
 	// player (client-side only)
 	virtual void EmitSound( IRecipientFilter& filter, int iEntIndex, int iChannel, const char *pSample, 
-		float flVolume, float flAttenuation, int iFlags = 0, int iPitch = PITCH_NORM, 
+		float flVolume, float flAttenuation, int iFlags = 0, int iPitch = PITCH_NORM, int iSpecialDSP = 0,
 		const Vector *pOrigin = NULL, const Vector *pDirection = NULL, CUtlVector< Vector >* pUtlVecOrigins = NULL, bool bUpdatePositions = true, float soundtime = 0.0f, int speakerentity = -1 ) = 0;
 
 	virtual void EmitSound( IRecipientFilter& filter, int iEntIndex, int iChannel, const char *pSample, 
-		float flVolume, soundlevel_t iSoundlevel, int iFlags = 0, int iPitch = PITCH_NORM, 
+		float flVolume, soundlevel_t iSoundlevel, int iFlags = 0, int iPitch = PITCH_NORM,  int iSpecialDSP = 0,
 		const Vector *pOrigin = NULL, const Vector *pDirection = NULL, CUtlVector< Vector >* pUtlVecOrigins = NULL, bool bUpdatePositions = true, float soundtime = 0.0f, int speakerentity = -1 ) = 0;
 
 	virtual void EmitSentenceByIndex( IRecipientFilter& filter, int iEntIndex, int iChannel, int iSentenceIndex,