diff --git a/voicebot/main.py b/voicebot/main.py
index 124aa65..3347088 100644
--- a/voicebot/main.py
+++ b/voicebot/main.py
@@ -391,12 +391,12 @@ class SilentAudioTrack(MediaStreamTrack):
         """Generate silent audio frames"""
         pts, time_base = await self.next_timestamp()
 
-        # Create silent audio data
-        samples = np.zeros((self.samples_per_frame,), dtype=np.float32)
+        # Create silent audio data in s16 format (required by Opus encoder)
+        samples = np.zeros((self.samples_per_frame,), dtype=np.int16)
 
         # Convert to AudioFrame
         frame = AudioFrame.from_ndarray(
-            samples.reshape(1, -1), format="flt", layout="mono"
+            samples.reshape(1, -1), format="s16", layout="mono"
         )
         frame.sample_rate = self.sample_rate
         frame.pts = pts