diff --git a/requirements.txt b/requirements.txt
index bc679f4..8a6ee6e 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -7,3 +7,4 @@ sphinx
 sphinx_rtd_theme
 pre-commit
 python-dotenv
+numpy<=1.16.6
diff --git a/src/robot_interface/endpoints/audio_sender.py b/src/robot_interface/endpoints/audio_sender.py
index 86dc66c..e168285 100644
--- a/src/robot_interface/endpoints/audio_sender.py
+++ b/src/robot_interface/endpoints/audio_sender.py
@@ -37,7 +37,6 @@ class AudioCapturer(object):
     @abstractmethod
     def generate_chunk(self):
         raise NotImplementedError()
-    
 
 
 class QiAudioCapturer(AudioCapturer):
@@ -69,15 +68,13 @@ class QiAudioCapturer(AudioCapturer):
         except:
             pass
 
-
-    def audio_gen(self):
+    def generate_chunk(self):
         try:
             chunk = self.q.get(True, 0.1)
             return chunk
         except Queue.Empty:
             return None
 
-
     # Callback invoked by NAOqi
     def processRemote(self, nbOfChannels, nbOfSamplesByChannel, timeStamp, inputBuffer):
         raw_pcm = bytes(inputBuffer)
@@ -91,10 +88,11 @@ class QiAudioCapturer(AudioCapturer):
         pcm_f32 = np.append(self.overflow, pcm_f32)
 
         for i in range(len(pcm_f32) // 512):
-            self.q.put_nowait(pcm_f32[i * 512 : (i + 1) * 512])
+            self.q.put_nowait(pcm_f32[i * 512 : (i + 1) * 512].tobytes())
 
         self.overflow = pcm_f32[len(pcm_f32) // 512 * 512 :]
 
+
 class StandaloneAudioCapturer:
     pass
 
@@ -108,8 +106,8 @@ class AudioSender(SocketBase):
 
         self.capturer = self.choose_capturer()
 
-
     def start(self):
+        self.capturer.setup()
         self.thread.start()
 
     def close(self):
@@ -120,7 +118,7 @@ class AudioSender(SocketBase):
         while not state.exit_event.is_set():
             chunk = self.capturer.generate_chunk()
 
-            if not chunk or state.is_speaking:
+            if chunk is None or state.is_speaking:
                 continue
 
             self.socket.send(chunk)