diff --git a/src/engine/platform/gb.cpp b/src/engine/platform/gb.cpp
index 76915716..8ca75f92 100644
--- a/src/engine/platform/gb.cpp
+++ b/src/engine/platform/gb.cpp
@@ -29,21 +29,59 @@ static unsigned char gbVolMap[16]={
   0x20, 0x20, 0x20, 0x20
 };
 
+static unsigned char noiseTable[256]={
+  0,
+  0xf7, 0xf6, 0xf5, 0xf4,
+  0xe7, 0xe6, 0xe5, 0xe4,
+  0xd7, 0xd6, 0xd5, 0xd4,
+  0xc7, 0xc6, 0xc5, 0xc4,
+  0xb7, 0xb6, 0xb5, 0xb4,
+  0xa7, 0xa6, 0xa5, 0xa4,
+  0x97, 0x96, 0x95, 0x94,
+  0x87, 0x86, 0x85, 0x84,
+  0x77, 0x76, 0x75, 0x74,
+  0x67, 0x66, 0x65, 0x64,
+  0x57, 0x56, 0x55, 0x54,
+  0x47, 0x46, 0x45, 0x44,
+  0x37, 0x36, 0x35, 0x34,
+  0x27, 0x26, 0x25, 0x24,
+  0x17, 0x16, 0x15, 0x14,
+  0x07, 0x06, 0x05, 0x04,
+  0x03, 0x02, 0x01, 0x00,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+};
+
 void DivPlatformGB::tick() {
   for (int i=0; i<4; i++) {
     chan[i].std.next();
     if (chan[i].std.hadArp) {
-      if (chan[i].std.arpMode) {
-        chan[i].baseFreq=round(FREQ_BASE/pow(2.0f,((float)(chan[i].std.arp)/12.0f)));
+      if (i==3) { // noise
+        if (chan[i].std.arpMode) {
+          chan[i].baseFreq=chan[i].std.arp;
+        } else {
+          chan[i].baseFreq=chan[i].note+chan[i].std.arp-12;
+        }
       } else {
-        chan[i].baseFreq=round(FREQ_BASE/pow(2.0f,((float)(chan[i].note+chan[i].std.arp-12)/12.0f)));
+        if (chan[i].std.arpMode) {
+          chan[i].baseFreq=round(FREQ_BASE/pow(2.0f,((float)(chan[i].std.arp)/12.0f)));
+        } else {
+          chan[i].baseFreq=round(FREQ_BASE/pow(2.0f,((float)(chan[i].note+chan[i].std.arp-12)/12.0f)));
+        }
       }
       chan[i].freqChanged=true;
     }
     if (chan[i].std.hadDuty) {
       chan[i].duty=chan[i].std.duty;
+      DivInstrument* ins=parent->getIns(chan[i].ins);
       if (i!=2) {
-        rWrite(16+i*5+1,(chan[i].duty&3)<<6);
+        rWrite(16+i*5+1,((chan[i].duty&3)<<6)|(63-(ins->gb.soundLen&63)));
       }
     }
     if (chan[i].std.hadWave) {
@@ -56,10 +94,14 @@ void DivPlatformGB::tick() {
       }
     }
     if (chan[i].freqChanged || chan[i].keyOn || chan[i].keyOff) {
-      chan[i].freq=(chan[i].baseFreq*(ONE_SEMITONE-chan[i].pitch))/ONE_SEMITONE;
+      DivInstrument* ins=parent->getIns(chan[i].ins);
+      if (i==3) { // noise
+        chan[i].freq=noiseTable[chan[i].baseFreq];
+      } else {
+        chan[i].freq=(chan[i].baseFreq*(ONE_SEMITONE-chan[i].pitch))/ONE_SEMITONE;
+      }
       if (chan[i].note>0x5d) chan[i].freq=0x01;
       if (chan[i].keyOn) {
-        DivInstrument* ins=parent->getIns(chan[i].ins);
         if (i==2) { // wave
           if (chan[i].wave<0) {
             chan[i].wave=0;
@@ -69,6 +111,7 @@ void DivPlatformGB::tick() {
           rWrite(16+i*5+2,gbVolMap[chan[i].vol]);
         } else {
           rWrite(16+i*5,0x00);
+          rWrite(16+i*5+1,((chan[i].duty&3)<<6)|(63-(ins->gb.soundLen&63)));
           rWrite(16+i*5+2,((chan[i].vol<<4))|(ins->gb.envLen&7)|((ins->gb.envDir&1)<<3));
         }
       }
@@ -79,8 +122,13 @@ void DivPlatformGB::tick() {
           rWrite(16+i*5+2,8);
         }
       }
-      rWrite(16+i*5+3,(2048-chan[i].freq)&0xff);
-      rWrite(16+i*5+4,(((2048-chan[i].freq)>>8)&7)|((chan[i].keyOn||chan[i].keyOff)?0x80:0x00));
+      if (i==3) { // noise
+        rWrite(16+i*5+3,chan[i].freq&0xff);
+        rWrite(16+i*5+4,((chan[i].keyOn||chan[i].keyOff)?0x80:0x00)|((ins->gb.soundLen<64)<<6));
+      } else {
+        rWrite(16+i*5+3,(2048-chan[i].freq)&0xff);
+        rWrite(16+i*5+4,(((2048-chan[i].freq)>>8)&7)|((chan[i].keyOn||chan[i].keyOff)?0x80:0x00)|((ins->gb.soundLen<63)<<6));
+      }
       if (chan[i].keyOn) chan[i].keyOn=false;
       if (chan[i].keyOff) chan[i].keyOff=false;
       chan[i].freqChanged=false;
@@ -98,7 +146,11 @@ void DivPlatformGB::tick() {
 int DivPlatformGB::dispatch(DivCommand c) {
   switch (c.cmd) {
     case DIV_CMD_NOTE_ON:
-      chan[c.chan].baseFreq=round(FREQ_BASE/pow(2.0f,((float)c.value/12.0f)));
+      if (c.chan==3) { // noise
+        chan[c.chan].baseFreq=c.value;
+      } else {
+        chan[c.chan].baseFreq=round(FREQ_BASE/pow(2.0f,((float)c.value/12.0f)));
+      }
       chan[c.chan].freqChanged=true;
       chan[c.chan].note=c.value;
       chan[c.chan].active=true;
@@ -156,6 +208,7 @@ int DivPlatformGB::dispatch(DivCommand c) {
       updateSNMode=true;
       break;
     case DIV_CMD_LEGATO:
+      if (c.chan==3) break;
       chan[c.chan].baseFreq=round(FREQ_BASE/pow(2.0f,((float)c.value/12.0f)));
       chan[c.chan].freqChanged=true;
       chan[c.chan].note=c.value;
diff --git a/src/engine/platform/gb.h b/src/engine/platform/gb.h
index 302f7c45..6e008536 100644
--- a/src/engine/platform/gb.h
+++ b/src/engine/platform/gb.h
@@ -19,13 +19,13 @@ class DivPlatformGB: public DivDispatch {
       ins(-1),
       note(0),
       duty(0),
-      wave(-1),
       active(false),
       insChanged(true),
       freqChanged(false),
       keyOn(false),
       keyOff(false),
-      vol(15) {}
+      vol(15),
+      wave(-1) {}
   };
   Channel chan[4];
   unsigned char snNoiseMode;
diff --git a/src/engine/platform/genesis.cpp b/src/engine/platform/genesis.cpp
index 714447f3..88a04542 100644
--- a/src/engine/platform/genesis.cpp
+++ b/src/engine/platform/genesis.cpp
@@ -5,6 +5,13 @@
 
 #include "genesisshared.h"
 
+static int dacRates[6]={
+  160,160,116,80,58,40
+};
+static unsigned char konOffs[6]={
+  0, 1, 2, 4, 5, 6
+};
+
 void DivPlatformGenesis::acquire(int& l, int& r) {
   static short o[2];
 
diff --git a/src/engine/platform/genesisshared.h b/src/engine/platform/genesisshared.h
index 8fd58120..cf0047e7 100644
--- a/src/engine/platform/genesisshared.h
+++ b/src/engine/platform/genesisshared.h
@@ -4,9 +4,6 @@ static unsigned short chanOffs[6]={
 static unsigned short opOffs[4]={
   0x00, 0x04, 0x08, 0x0c
 };
-static unsigned char konOffs[6]={
-  0, 1, 2, 4, 5, 6
-};
 static bool isOutput[8][4]={
   // 1     3     2    4
   {false,false,false,true},
@@ -21,9 +18,7 @@ static bool isOutput[8][4]={
 static unsigned char dtTable[8]={
   7,6,5,0,1,2,3,0
 };
-static int dacRates[6]={
-  160,160,116,80,58,40
-};
+
 static int orderedOps[4]={
   0,2,1,3
 };
diff --git a/src/engine/platform/sms.cpp b/src/engine/platform/sms.cpp
index 24d89ce0..9af28b49 100644
--- a/src/engine/platform/sms.cpp
+++ b/src/engine/platform/sms.cpp
@@ -156,7 +156,7 @@ int DivPlatformSMS::dispatch(DivCommand c) {
 int DivPlatformSMS::init(DivEngine* p, int channels, int sugRate) {
   parent=p;
   rate=223722;
-  sn=new sn76496_device("sn",223722);
+  sn=new sn76496_device(223722);
   sn->device_start();
   snNoiseMode=3;
   updateSNMode=false;
diff --git a/src/engine/platform/sound/gb/apu.c b/src/engine/platform/sound/gb/apu.c
index 7abac902..092dd29f 100644
--- a/src/engine/platform/sound/gb/apu.c
+++ b/src/engine/platform/sound/gb/apu.c
@@ -266,7 +266,6 @@ static void render(GB_gameboy_t *gb)
     }
     
     
-    /*
     if (gb->apu_output.interference_volume) {
         signed interference_bias = interference(gb);
         int16_t interference_sample = (interference_bias - gb->apu_output.interference_highpass);
@@ -276,7 +275,7 @@ static void render(GB_gameboy_t *gb)
         
         filtered_output.left = MAX(MIN(filtered_output.left + interference_bias, 0x7FFF), -0x8000);
         filtered_output.right = MAX(MIN(filtered_output.right + interference_bias, 0x7FFF), -0x8000);
-    }*/
+    }
 
     gb->apu_output.final_sample=filtered_output;
 }
diff --git a/src/engine/platform/sound/sn76496.cpp b/src/engine/platform/sound/sn76496.cpp
index e0c896b6..08c4cc38 100644
--- a/src/engine/platform/sound/sn76496.cpp
+++ b/src/engine/platform/sound/sn76496.cpp
@@ -148,7 +148,6 @@
 //#define NOISE_START 0x0f35
 
 sn76496_base_device::sn76496_base_device(
-		const char *tag,
 		int feedbackmask,
 		int noisetap1,
 		int noisetap2,
@@ -167,8 +166,8 @@ sn76496_base_device::sn76496_base_device(
 {
 }
 
-sn76496_device::sn76496_device(const char *tag, uint32_t clock)
-	: sn76496_base_device(tag, 0x8000, 0x01, 0x08, false, 1, false, false, clock)
+sn76496_device::sn76496_device(uint32_t clock)
+	: sn76496_base_device(0x8000, 0x01, 0x08, false, 1, false, false, clock)
 {
 }
 
diff --git a/src/engine/platform/sound/sn76496.h b/src/engine/platform/sound/sn76496.h
index 2c02d6d4..4311766d 100644
--- a/src/engine/platform/sound/sn76496.h
+++ b/src/engine/platform/sound/sn76496.h
@@ -20,7 +20,6 @@ public:
 
 protected:
 	sn76496_base_device(
-			const char *tag,
 			int feedbackmask,
 			int noisetap1,
 			int noisetap2,
@@ -59,7 +58,7 @@ private:
 class sn76496_device : public sn76496_base_device
 {
 public:
-	sn76496_device(const char *tag, uint32_t clock);
+	sn76496_device(uint32_t clock);
 };
 
 #endif // MAME_SOUND_SN76496_H