diff --git a/src/emucore/tia/Audio.cxx b/src/emucore/tia/Audio.cxx
index 7d35c9a89..427073496 100644
--- a/src/emucore/tia/Audio.cxx
+++ b/src/emucore/tia/Audio.cxx
@@ -47,6 +47,9 @@ void Audio::reset()
 {
   myCounter = 0;
   mySampleIndex = 0;
+  sumChannel0 = 0;
+  sumChannel1 = 0;
+  sumCt = 0;
 
   myChannel0.reset();
   myChannel1.reset();
@@ -64,8 +67,13 @@ void Audio::setAudioQueue(const shared_ptr<AudioQueue>& queue)
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 void Audio::phase1()
 {
-  const uInt8 sample0 = myChannel0.phase1();
-  const uInt8 sample1 = myChannel1.phase1();
+  // calculate average of all recent volume samples. the average for each
+  // channel is mixed to create a single audible value
+  const uInt8 sample0 = (uInt8)(sumChannel0/sumCt);
+  const uInt8 sample1 = (uInt8)(sumChannel1/sumCt);
+  sumChannel0 = 0;
+  sumChannel1 = 0;
+  sumCt = 0;
 
   addSample(sample0, sample1);
 #ifdef GUI_SUPPORT
diff --git a/src/emucore/tia/Audio.hxx b/src/emucore/tia/Audio.hxx
index 9a054c5b0..c656ed5a3 100644
--- a/src/emucore/tia/Audio.hxx
+++ b/src/emucore/tia/Audio.hxx
@@ -68,6 +68,10 @@ class Audio : public Serializable
     AudioChannel myChannel0;
     AudioChannel myChannel1;
 
+	uInt32 sumChannel0;
+	uInt32 sumChannel1;
+	uInt32 sumCt;
+
     std::array<Int16, 0x1e + 1> myMixingTableSum;
     std::array<Int16, 0x0f + 1> myMixingTableIndividual;
 
@@ -92,6 +96,12 @@ class Audio : public Serializable
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 void Audio::tick()
 {
+  // volume for each channel is sampled every color clock. the average of
+  // these samples will be taken twice a scanline in the phase1() function
+  sumChannel0 += (uInt32)myChannel0.phase1();
+  sumChannel1 += (uInt32)myChannel1.phase1();
+  sumCt++;
+
   switch (myCounter) {
     case 9:
     case 81: