diff --git a/AV.cc b/AV.cc
index 5c01484..4454b47 100644
--- a/AV.cc
+++ b/AV.cc
@@ -8,16 +8,9 @@
 #include <math.h>
 using namespace std;
 
-static void AV_sound_callback(void * userdata, Uint8 * stream, int len)
+void AV_sound_callback(void * userdata, Uint8 * stream, int len)
 {
-    static int pos = 0;
-    Sint16 * str = (Sint16 *) stream;
-    for (int i = 0; i < len / 4; i++)
-    {
-        str[i*2] = (Sint16) (32000.0 * sin(pos * 263.0 / AV_SOUND_RATE * 2.0 * M_PI));
-        str[i*2+1] = 0;
-        pos++;
-    }
+    ((AV *)userdata)->playCallback(stream, len);
 }
 
 AV::AV()
@@ -121,6 +114,18 @@ void AV::stop()
     }
 }
 
+void AV::playCallback(Uint8 * stream, int len)
+{
+    static int pos = 0;
+    Sint16 * str = (Sint16 *) stream;
+    for (int i = 0; i < len / 4; i++)
+    {
+        str[i*2] = (Sint16) (32000.0 * sin(pos * 440.0 / AV_SOUND_RATE * 2.0 * M_PI));
+        str[i*2+1] = 0;
+        pos++;
+    }
+}
+
 AV::Sound::Sound(AV & av)
     : m_av(av)
 {
diff --git a/AV.h b/AV.h
index a00ebe5..8dcfcab 100644
--- a/AV.h
+++ b/AV.h
@@ -55,7 +55,11 @@ class AV
         }
         refptr<Sound> createSound() { return new Sound(*this); }
 
+        friend void AV_sound_callback(void * userdata, Uint8 * stream, int len);
+
     protected:
+        void playCallback(Uint8 * stream, int len);
+
         int m_defaultWidth;
         int m_defaultHeight;
         int m_width;