diff --git a/docs/rh-log.txt b/docs/rh-log.txt
index fb81752b35..c81a2fb8ef 100644
--- a/docs/rh-log.txt
+++ b/docs/rh-log.txt
@@ -1,4 +1,11 @@
 October 26, 2009
+- Added new sound sequence ACS functions:
+    SoundSequenceOnActor(int tid, string seqname);
+    SoundSequenceOnSector(int tag, string seqname, int location);
+    SoundSequenceOnPolyobj(int polynum, string seqname);
+  SoundSequenceOnSector takes an extra parameter that specifies where in the
+  sector the sound comes from (floor, ceiling, interior, or all of it). See
+  the SECSEQ defines in zdefs.acs.
 - Fixed: R_RenderDecal() must save various Wall globals, because the originals
   may still be needed. In particular, when drawing a seg with a midtexture is
   split by foreground geometry, the first drawseg generated from it will have
diff --git a/src/p_acs.cpp b/src/p_acs.cpp
index a0d2811ad2..c6f4791c40 100644
--- a/src/p_acs.cpp
+++ b/src/p_acs.cpp
@@ -2910,6 +2910,9 @@ enum EACSFunctions
 	ACSF_CheckActorClass,
 	ACSF_SetUserArray,
 	ACSF_GetUserArray,
+	ACSF_SoundSequenceOnActor,
+	ACSF_SoundSequenceOnSector,
+	ACSF_SoundSequenceOnPolyobj,
 };
 
 int DLevelScript::SideFromID(int id, int side)
@@ -3257,6 +3260,61 @@ int DLevelScript::CallFunction(int argCount, int funcIndex, SDWORD *args)
 			return a->GetClass()->TypeName == FName(FBehavior::StaticLookupString(args[1]));
 		}
 
+		case ACSF_SoundSequenceOnActor:
+			{
+				const char *seqname = FBehavior::StaticLookupString(args[1]);
+				if (seqname != NULL)
+				{
+					if (args[0] == 0)
+					{
+						if (activator != NULL)
+						{
+							SN_StartSequence(activator, seqname, 0);
+						}
+					}
+					else
+					{
+						FActorIterator it(args[0]);
+						AActor *actor;
+
+						while ( (actor = it.Next()) )
+						{
+							SN_StartSequence(actor, seqname, 0);
+						}
+					}
+				}
+			}
+			break;
+
+		case ACSF_SoundSequenceOnSector:
+			{
+				const char *seqname = FBehavior::StaticLookupString(args[1]);
+				int space = args[2] < CHAN_FLOOR || args[2] > CHAN_INTERIOR ? CHAN_FULLHEIGHT : args[2];
+				if (seqname != NULL)
+				{
+					int secnum = -1;
+
+					while ((secnum = P_FindSectorFromTag(args[0], secnum)) >= 0)
+					{
+						SN_StartSequence(&sectors[secnum], args[2], seqname, 0);
+					}
+				}
+			}
+			break;
+
+		case ACSF_SoundSequenceOnPolyobj:
+			{
+				const char *seqname = FBehavior::StaticLookupString(args[1]);
+				if (seqname != NULL)
+				{
+					FPolyObj *poly = PO_GetPolyobj(args[0]);
+					if (poly != NULL)
+					{
+						SN_StartSequence(poly, seqname, 0);
+					}
+				}
+			}
+			break;
 
 		default:
 			break;
@@ -5083,7 +5141,7 @@ int DLevelScript::RunScript ()
 			lookup = FBehavior::StaticLookupString (STACK(1));
 			if (lookup != NULL)
 			{
-				if (activationline)
+				if (activationline != NULL)
 				{
 					SN_StartSequence (activationline->frontsector, CHAN_FULLHEIGHT, lookup, 0);
 				}
diff --git a/src/p_local.h b/src/p_local.h
index 0be5c11e0e..4d37bc8de1 100644
--- a/src/p_local.h
+++ b/src/p_local.h
@@ -517,6 +517,7 @@ bool PO_RotatePolyobj (int num, angle_t angle);
 void PO_Init ();
 bool PO_Busy (int polyobj);
 void PO_ClosestPoint(const FPolyObj *poly, fixed_t ox, fixed_t oy, fixed_t &x, fixed_t &y, seg_t **seg);
+struct FPolyObj *PO_GetPolyobj(int polyNum);
 
 //
 // P_SPEC
diff --git a/src/po_man.cpp b/src/po_man.cpp
index d88c67589b..ebafff46fd 100644
--- a/src/po_man.cpp
+++ b/src/po_man.cpp
@@ -120,7 +120,6 @@ void PO_Init (void);
 
 // PRIVATE FUNCTION PROTOTYPES ---------------------------------------------
 
-static FPolyObj *GetPolyobj (int polyNum);
 static int GetPolyobjMirror (int poly);
 static void UpdateSegBBox (seg_t *seg);
 static void RotatePt (int an, fixed_t *x, fixed_t *y, fixed_t startSpotX,
@@ -184,7 +183,7 @@ DPolyAction::DPolyAction (int polyNum)
 
 void DPolyAction::Destroy()
 {
-	FPolyObj *poly = GetPolyobj (m_PolyObj);
+	FPolyObj *poly = PO_GetPolyobj (m_PolyObj);
 
 	if (poly->specialdata == NULL || poly->specialdata == this)
 	{
@@ -197,7 +196,7 @@ void DPolyAction::Destroy()
 
 void DPolyAction::SetInterpolation ()
 {
-	FPolyObj *poly = GetPolyobj (m_PolyObj);
+	FPolyObj *poly = PO_GetPolyobj (m_PolyObj);
 	m_Interpolation = poly->SetInterpolation();
 }
 
@@ -278,7 +277,7 @@ void DRotatePoly::Tick ()
 		m_Dist -= absSpeed;
 		if (m_Dist == 0)
 		{
-			FPolyObj *poly = GetPolyobj (m_PolyObj);
+			FPolyObj *poly = PO_GetPolyobj (m_PolyObj);
 			if (poly->specialdata == this)
 			{
 				poly->specialdata = NULL;
@@ -307,7 +306,7 @@ bool EV_RotatePoly (line_t *line, int polyNum, int speed, int byteAngle,
 	DRotatePoly *pe;
 	FPolyObj *poly;
 
-	if ( (poly = GetPolyobj(polyNum)) )
+	if ( (poly = PO_GetPolyobj(polyNum)) )
 	{
 		if (poly->specialdata && !overRide)
 		{ // poly is already moving
@@ -338,9 +337,9 @@ bool EV_RotatePoly (line_t *line, int polyNum, int speed, int byteAngle,
 	poly->specialdata = pe;
 	SN_StartSequence (poly, poly->seqType, SEQ_DOOR, 0);
 	
-	while ( (mirror = GetPolyobjMirror( polyNum)) )
+	while ( (mirror = GetPolyobjMirror(polyNum)) )
 	{
-		poly = GetPolyobj(mirror);
+		poly = PO_GetPolyobj(mirror);
 		if (poly == NULL)
 		{
 			I_Error ("EV_RotatePoly: Invalid polyobj num: %d\n", polyNum);
@@ -390,7 +389,7 @@ void DMovePoly::Tick ()
 		m_Dist -= absSpeed;
 		if (m_Dist <= 0)
 		{
-			poly = GetPolyobj (m_PolyObj);
+			poly = PO_GetPolyobj (m_PolyObj);
 			if (poly->specialdata == this)
 			{
 				poly->specialdata = NULL;
@@ -421,7 +420,7 @@ bool EV_MovePoly (line_t *line, int polyNum, int speed, angle_t angle,
 	FPolyObj *poly;
 	angle_t an;
 
-	if ( (poly = GetPolyobj(polyNum)) )
+	if ( (poly = PO_GetPolyobj(polyNum)) )
 	{
 		if (poly->specialdata && !overRide)
 		{ // poly is already moving
@@ -455,7 +454,7 @@ bool EV_MovePoly (line_t *line, int polyNum, int speed, angle_t angle,
 
 	while ( (mirror = GetPolyobjMirror(polyNum)) )
 	{
-		poly = GetPolyobj(mirror);
+		poly = PO_GetPolyobj(mirror);
 		if (poly && poly->specialdata && !overRide)
 		{ // mirroring poly is already in motion
 			break;
@@ -493,7 +492,7 @@ void DPolyDoor::Tick ()
 	{
 		if (!--m_Tics)
 		{
-			poly = GetPolyobj (m_PolyObj);
+			poly = PO_GetPolyobj (m_PolyObj);
 			SN_StartSequence (poly, poly->seqType, SEQ_DOOR, m_Close);
 		}
 		return;
@@ -507,7 +506,7 @@ void DPolyDoor::Tick ()
 			m_Dist -= absSpeed;
 			if (m_Dist <= 0)
 			{
-				poly = GetPolyobj (m_PolyObj);
+				poly = PO_GetPolyobj (m_PolyObj);
 				SN_StopSequence (poly);
 				if (!m_Close)
 				{
@@ -531,7 +530,7 @@ void DPolyDoor::Tick ()
 		}
 		else
 		{
-			poly = GetPolyobj (m_PolyObj);
+			poly = PO_GetPolyobj (m_PolyObj);
 			if (poly->crush || !m_Close)
 			{ // continue moving if the poly is a crusher, or is opening
 				return;
@@ -560,7 +559,7 @@ void DPolyDoor::Tick ()
 			m_Dist -= absSpeed;
 			if (m_Dist <= 0)
 			{
-				poly = GetPolyobj (m_PolyObj);
+				poly = PO_GetPolyobj (m_PolyObj);
 				SN_StopSequence (poly);
 				if (!m_Close)
 				{
@@ -581,7 +580,7 @@ void DPolyDoor::Tick ()
 		}
 		else
 		{
-			poly = GetPolyobj (m_PolyObj);
+			poly = PO_GetPolyobj (m_PolyObj);
 			if(poly->crush || !m_Close)
 			{ // continue moving if the poly is a crusher, or is opening
 				return;
@@ -614,7 +613,7 @@ bool EV_OpenPolyDoor (line_t *line, int polyNum, int speed, angle_t angle,
 	DPolyDoor *pd;
 	FPolyObj *poly;
 
-	if( (poly = GetPolyobj(polyNum)) )
+	if( (poly = PO_GetPolyobj(polyNum)) )
 	{
 		if (poly->specialdata)
 		{ // poly is already moving
@@ -649,7 +648,7 @@ bool EV_OpenPolyDoor (line_t *line, int polyNum, int speed, angle_t angle,
 
 	while ( (mirror = GetPolyobjMirror (polyNum)) )
 	{
-		poly = GetPolyobj (mirror);
+		poly = PO_GetPolyobj (mirror);
 		if (poly && poly->specialdata)
 		{ // mirroring poly is already in motion
 			break;
@@ -683,11 +682,11 @@ bool EV_OpenPolyDoor (line_t *line, int polyNum, int speed, angle_t angle,
 
 //==========================================================================
 //
-// GetPolyobj
+// PO_GetPolyobj
 //
 //==========================================================================
 
-static FPolyObj *GetPolyobj (int polyNum)
+FPolyObj *PO_GetPolyobj (int polyNum)
 {
 	int i;
 
@@ -844,7 +843,7 @@ bool PO_MovePolyobj (int num, int x, int y, bool force)
 {
 	FPolyObj *po;
 
-	if (!(po = GetPolyobj (num)))
+	if (!(po = PO_GetPolyobj (num)))
 	{
 		I_Error ("PO_MovePolyobj: Invalid polyobj number: %d\n", num);
 	}
@@ -954,7 +953,7 @@ bool PO_RotatePolyobj (int num, angle_t angle)
 	FPolyObj *po;
 	bool blocked;
 
-	if(!(po = GetPolyobj(num)))
+	if(!(po = PO_GetPolyobj(num)))
 	{
 		I_Error("PO_RotatePolyobj: Invalid polyobj number: %d\n", num);
 	}
@@ -1662,7 +1661,7 @@ bool PO_Busy (int polyobj)
 {
 	FPolyObj *poly;
 
-	poly = GetPolyobj (polyobj);
+	poly = PO_GetPolyobj (polyobj);
 	if (poly == NULL || poly->specialdata == NULL)
 	{
 		return false;