diff --git a/core/duplex_pipeline.py b/core/duplex_pipeline.py
index b80cc36..b6ae930 100644
--- a/core/duplex_pipeline.py
+++ b/core/duplex_pipeline.py
@@ -108,6 +108,8 @@ class DuplexPipeline:
         self._is_bot_speaking = False
         self._current_turn_task: Optional[asyncio.Task] = None
         self._audio_buffer: bytes = b""
+        max_buffer_seconds = settings.max_audio_buffer_seconds if hasattr(settings, "max_audio_buffer_seconds") else 30
+        self._max_audio_buffer_bytes = int(settings.sample_rate * 2 * max_buffer_seconds)
         self._last_vad_status: str = "Silence"
         
         # Interruption handling
@@ -263,6 +265,9 @@ class DuplexPipeline:
             # 3. Buffer audio for ASR
             if vad_status == "Speech" or self.conversation.state == ConversationState.LISTENING:
                 self._audio_buffer += pcm_bytes
+                if len(self._audio_buffer) > self._max_audio_buffer_bytes:
+                    # Keep only the most recent audio to cap memory usage
+                    self._audio_buffer = self._audio_buffer[-self._max_audio_buffer_bytes:]
                 await self.asr_service.send_audio(pcm_bytes)
                 
                 # For SiliconFlow ASR, trigger interim transcription periodically