SampleStream also holds on to the AudioUnit so it is not dropped

src/coreaudio/mod.rs

@@ -93,12 +93,13 @@ impl<T> Buffer<T> where T: Sample {
 
 pub struct Voice {
     playing: bool,
-    audio_unit: AudioUnit
+    audio_unit: Arc<Mutex<AudioUnit>>,
 }
 
 #[allow(dead_code)] // the audio_unit will be dropped if we don't hold it.
 pub struct SamplesStream {
     inner: Arc<Mutex<SamplesStreamInner>>,
+    audio_unit: Arc<Mutex<AudioUnit>>,
 }
 
 
@@ -196,20 +197,24 @@ impl Voice {
 
         try!(audio_unit.start().map_err(convert_error));
 
+        let au_arc = Arc::new(Mutex::new(audio_unit));
+
         let samples_stream = SamplesStream {
             inner: inner,
+            audio_unit: au_arc.clone(),
         };
 
         Ok((Voice {
             playing: true,
-            audio_unit: audio_unit
+            audio_unit: au_arc.clone(), 
         }, samples_stream))
     }
 
     #[inline]
     pub fn play(&mut self) {
         if !self.playing {
-            self.audio_unit.start().unwrap();
+            let mut unit = self.audio_unit.lock().unwrap();
+            unit.start().unwrap();
             self.playing = true;
         }
     }
@@ -217,7 +222,8 @@ impl Voice {
     #[inline]
     pub fn pause(&mut self) {
         if self.playing {
-            self.audio_unit.stop().unwrap();
+            let mut unit = self.audio_unit.lock().unwrap();
+            unit.stop().unwrap();
             self.playing = false;
         }
     }