diff --git a/BizHawk.Emulation/BizHawk.Emulation.csproj b/BizHawk.Emulation/BizHawk.Emulation.csproj
index 1d57848153..5b8f4d6330 100644
--- a/BizHawk.Emulation/BizHawk.Emulation.csproj
+++ b/BizHawk.Emulation/BizHawk.Emulation.csproj
@@ -441,6 +441,7 @@
     <Compile Include="Properties\svnrev.cs" />
     <Compile Include="QuickCollections.cs" />
     <Compile Include="Sound\CDAudio.cs" />
+    <Compile Include="Sound\MMC5Audio.cs" />
     <Compile Include="Sound\Utilities\BlipBuffer.cs" />
     <Compile Include="Sound\Utilities\DCFilter.cs" />
     <Compile Include="Sound\Utilities\Equalizer.cs" />
diff --git a/BizHawk.Emulation/Consoles/Nintendo/NES/Boards/ExROM.cs b/BizHawk.Emulation/Consoles/Nintendo/NES/Boards/ExROM.cs
index 24c2be1726..fd113563f1 100644
--- a/BizHawk.Emulation/Consoles/Nintendo/NES/Boards/ExROM.cs
+++ b/BizHawk.Emulation/Consoles/Nintendo/NES/Boards/ExROM.cs
@@ -37,12 +37,14 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 		int wram_bank;
 		byte[] EXRAM = new byte[1024];
 		byte multiplicand, multiplier;
+		Sound.MMC5Audio audio;
 		//regeneratable state
 		IntBuffer a_banks_1k = new IntBuffer(8);
 		IntBuffer b_banks_1k = new IntBuffer(8);
 		IntBuffer prg_banks_8k = new IntBuffer(4);
 		byte product_low, product_high;
 		int last_nt_read;
+		bool irq_audio;
 
 		public MemoryDomain GetExRAM()
 		{
@@ -76,6 +78,7 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 			SyncCHRBanks();
 			SyncMultiplier();
 			SyncIRQ();
+			audio.SyncState(ser);
 		}
 
 		public override void Dispose()
@@ -111,6 +114,9 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 
 			PoweronState();
 
+			if (NES.apu != null)
+				audio = new Sound.MMC5Audio(NES.apu.ExternalQueue, (e) => { irq_audio = e; SyncIRQ(); });
+
 			return true;
 		}
 
@@ -320,6 +326,11 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 		public override void WriteEXP(int addr, byte value)
 		{
 			//NES.LogLine("MMC5 WriteEXP: ${0:x4} = ${1:x2}", addr, value);
+			if (addr >= 0x1000 && addr <= 0x1015)
+			{
+				audio.WriteExp(addr + 0x4000, value);
+				return;
+			}
 			switch (addr)
 			{
 				case 0x1100: //$5100:  [.... ..PP]    PRG Mode Select:
@@ -440,6 +451,14 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 				case 0x1206: //$5206:  high 8 bits of product
 					ret = product_high;
 					break;
+
+				case 0x1015: // $5015: apu status
+					ret = audio.Read5015();
+					break;
+
+				case 0x1010: // $5010: apu PCM
+					ret = audio.Read5010();
+					break;
 			}
 
 			//TODO - additional r/w timing security
@@ -455,7 +474,7 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 
 		void SyncIRQ()
 		{
-			IRQSignal = (irq_pending && irq_enabled);
+			IRQSignal = (irq_pending && irq_enabled) || irq_audio;
 		}
 
 		public override void ClockPPU()
@@ -493,6 +512,11 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 
 		}
 
+		public override void ClockCPU()
+		{
+			audio.Clock();
+		}
+
 		void SetBank(IntBuffer target, int offset, int size, int value)
 		{
 			value &= ~(size-1);
diff --git a/BizHawk.Emulation/Sound/MMC5Audio.cs b/BizHawk.Emulation/Sound/MMC5Audio.cs
new file mode 100644
index 0000000000..6152bb658e
--- /dev/null
+++ b/BizHawk.Emulation/Sound/MMC5Audio.cs
@@ -0,0 +1,306 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace BizHawk.Emulation.Sound
+{
+	public class MMC5Audio
+	{
+		class Pulse
+		{
+			// regs
+			int V;
+			int T;
+			int L;
+			int D;
+			bool LenCntDisable;
+			bool ConstantVolume;
+			bool Enable;
+			// envelope
+			bool estart;
+			int etime;
+			int ecount;
+			// length
+			static int[] lenlookup =
+			{
+				10,254, 20,  2, 40,  4, 80,  6, 160,  8, 60, 10, 14, 12, 26, 14,
+				12, 16, 24, 18, 48, 20, 96, 22, 192, 24, 72, 26, 16, 28, 32, 30
+			};
+			int length;
+
+			// pulse
+			int sequence;
+			static int[,] sequencelookup =
+			{
+				{0,0,0,0,0,0,0,1},
+				{0,0,0,0,0,0,1,1},
+				{0,0,0,0,1,1,1,1},
+				{1,1,1,1,1,1,0,0}
+			};
+			int clock;
+			int output;
+
+			public Action<int> SendDiff;
+
+			public Pulse(Action<int> SendDiff)
+			{
+				this.SendDiff = SendDiff;
+			}
+
+			public void SyncState(Serializer ser)
+			{
+				ser.Sync("V", ref V);
+				ser.Sync("T", ref T);
+				ser.Sync("L", ref L);
+				ser.Sync("D", ref D);
+				ser.Sync("LenCntDisable", ref LenCntDisable);
+				ser.Sync("ConstantVolume", ref ConstantVolume);
+				ser.Sync("Enable", ref Enable);
+				ser.Sync("estart", ref estart);
+				ser.Sync("etime", ref etime);
+				ser.Sync("ecount", ref ecount);
+				ser.Sync("length", ref length);
+				ser.Sync("sequence", ref sequence);
+				ser.Sync("clock", ref clock);
+				ser.Sync("output", ref output);
+			}
+
+			public void Write0(byte val)
+			{
+				V = val & 15;
+				ConstantVolume = val.Bit(4);
+				LenCntDisable = val.Bit(5);
+				D = val >> 6;
+			}
+			public void Write2(byte val)
+			{
+				T &= 0x700;
+				T |= val;
+			}
+			public void Write3(byte val)
+			{
+				T &= 0xff;
+				T |= val << 8 & 0x700;
+				L = val >> 3;
+				estart = true;
+				if (Enable)
+					length = lenlookup[L];
+				sequence = 0;
+			}
+			public void SetEnable(bool val)
+			{
+				Enable = val;
+				if (!Enable)
+					length = 0;
+			}
+			public bool ReadLength()
+			{
+				return length > 0;
+			}
+
+			public void ClockFrame()
+			{
+				// envelope
+				if (estart)
+				{
+					estart = false;
+					ecount = 15;
+					etime = V;
+				}
+				else
+				{
+					etime--;
+					if (etime < 0)
+					{
+						etime = V;
+						if (ecount > 0)
+						{
+							ecount--;
+						}
+						else if (LenCntDisable)
+						{
+							ecount = 15;
+						}
+					}
+				}
+				// length
+				if (Enable && !LenCntDisable && length > 0)
+				{
+					length--;
+				}
+			}
+
+			public void Clock()
+			{
+				clock--;
+				if (clock < 0)
+				{
+					clock = T * 2;
+					sequence--;
+					if (sequence < 0)
+						sequence += 8;
+
+					int sequenceval = sequencelookup[D, sequence];
+
+					int newvol = 0;
+
+					if (sequenceval > 0 && length > 0)
+					{
+						if (ConstantVolume)
+							newvol = V;
+						else
+							newvol = ecount;
+					}
+
+					if (newvol != output)
+					{
+						//Console.WriteLine("{0},{1}", newvol, output);
+						SendDiff(output - newvol);
+						output = newvol;
+					}
+				}
+			}
+		}
+
+		Pulse[] pulse = new Pulse[2];
+		
+		/// <summary>
+		/// 
+		/// </summary>
+		/// <param name="addr">0x5000..0x5015</param>
+		/// <param name="val"></param>
+		public void WriteExp(int addr, byte val)
+		{
+			switch (addr)
+			{
+				case 0x5000: pulse[0].Write0(val); break;
+				case 0x5002: pulse[0].Write2(val); break;
+				case 0x5003: pulse[0].Write3(val); break;
+				case 0x5004: pulse[1].Write0(val); break;
+				case 0x5006: pulse[1].Write2(val); break;
+				case 0x5007: pulse[1].Write3(val); break;
+				case 0x5010: // pcm mode/irq
+					PCMRead = val.Bit(0);
+					PCMEnableIRQ = val.Bit(7);
+					RaiseIRQ(PCMEnableIRQ && PCMIRQTriggered);
+					break;
+				case 0x5011: // PCM value
+					if (!PCMRead)
+						WritePCM(val);
+					break;
+				case 0x5015:
+					pulse[0].SetEnable(val.Bit(0));
+					pulse[1].SetEnable(val.Bit(1));
+					break;
+			}
+		}
+
+		public byte Read5015()
+		{
+			byte ret = 0;
+			if (pulse[0].ReadLength())
+				ret |= 1;
+			if (pulse[1].ReadLength())
+				ret |= 2;
+			return ret;
+		}
+
+		public byte Read5010()
+		{
+			byte ret = 0;
+			if (PCMEnableIRQ && PCMIRQTriggered)
+			{
+				ret |= 0x80;
+			}
+			PCMIRQTriggered = false; // ack
+			RaiseIRQ(PCMEnableIRQ && PCMIRQTriggered);
+			return ret;
+		}
+
+		/// <summary>
+		/// call for 8000:bfff reads
+		/// </summary>
+		/// <param name="val"></param>
+		public void ReadROMTrigger(byte val)
+		{
+			if (PCMRead)
+				WritePCM(val);
+		}
+
+		void WritePCM(byte val)
+		{
+			if (val == 0)
+			{
+				PCMIRQTriggered = true;
+			}
+			else
+			{
+				PCMIRQTriggered = false;
+				// can't set diff here, because APU cycle clock might be wrong
+				PCMNextVal = val;
+			}
+			RaiseIRQ(PCMEnableIRQ && PCMIRQTriggered);
+		}
+
+		Action<bool> RaiseIRQ;
+
+		const int framereload = 7458; // ???
+		int frame = 0;
+		bool PCMRead;
+		bool PCMEnableIRQ;
+		bool PCMIRQTriggered;
+		byte PCMVal;
+		byte PCMNextVal;
+
+		public void SyncState(Serializer ser)
+		{
+			ser.BeginSection("MMC5Audio");
+			ser.Sync("frame", ref frame);
+			pulse[0].SyncState(ser);
+			pulse[1].SyncState(ser);
+			ser.Sync("PCMRead", ref PCMRead);
+			ser.Sync("PCMEnableIRQ", ref PCMEnableIRQ);
+			ser.Sync("PCMIRQTriggered", ref PCMIRQTriggered);
+			ser.Sync("PCMVal", ref PCMVal);
+			ser.Sync("PCMNextVal", ref PCMNextVal);
+			ser.EndSection();
+			if (ser.IsReader)
+				RaiseIRQ(PCMEnableIRQ && PCMIRQTriggered);
+		}
+
+		public void Clock()
+		{
+			pulse[0].Clock();
+			pulse[1].Clock();
+			frame++;
+			if (frame == framereload)
+			{
+				frame = 0;
+				pulse[0].ClockFrame();
+				pulse[1].ClockFrame();
+			}
+			if (PCMNextVal != PCMVal)
+			{
+				enqueuer(20 * (int)(PCMVal - PCMNextVal));
+				PCMVal = PCMNextVal;
+			}
+		}
+
+		Action<int> enqueuer;
+
+		void PulseAddDiff(int value)
+		{
+			enqueuer(value * 370);
+			//Console.WriteLine(value);
+		}
+
+		public MMC5Audio(Action<int> enqueuer, Action<bool> RaiseIRQ)
+		{
+			this.enqueuer = enqueuer;
+			this.RaiseIRQ = RaiseIRQ;
+			for (int i = 0; i < pulse.Length; i++)
+				pulse[i] = new Pulse(PulseAddDiff);
+		}
+	}
+}