Syd Adams:

Patch to enable atc chatter (and any other arbitrary "message" audio file)
to be played at any specified volume.  (Previously these messages were always
played at a hardcoded volume of 1.0)

src/Main/fg_commands.cxx

@@ -1157,8 +1157,9 @@ do_play_audio_message (const SGPropertyNode * arg)
     FGFX *fx = (FGFX *)globals->get_subsystem("fx");
     string path = arg->getStringValue("path");
     string file = arg->getStringValue("file");
+    double volume = arg->getDoubleValue("volume");
     // cout << "playing " << path << " / " << file << endl;
-    fx->play_message( path, file );
+    fx->play_message( path, file, volume );
 
     return true;
 }

src/Sound/fg_fx.cxx

@@ -187,17 +187,17 @@ FGFX::update (double dt)
 void
 FGFX::play_message( SGSoundSample *_sample )
 {
-    _sample->set_volume( 1.0 );
     _samplequeue.push( _sample );
 }
 void
-FGFX::play_message( const string path, const string fname )
+FGFX::play_message( const string path, const string fname, double volume )
 {
     if (globals->get_soundmgr()->is_working() == false) {
         return;
     }
     SGSoundSample *sample;
     sample = new SGSoundSample( path.c_str(), fname.c_str() );
+    sample->set_volume( volume );
     play_message( sample );
 }
 

src/Sound/fg_fx.hxx

@@ -72,7 +72,7 @@ public:
      * in order.
      */
     void play_message( SGSoundSample *_sample );
-    void play_message( const string path, const string fname );
+    void play_message( const string path, const string fname, double volume );
 
 private: