diff --git a/Dockerfile b/Dockerfile
index b57857e..073464f 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -17,4 +17,4 @@ RUN pip install .
 
 EXPOSE 3000
 
-CMD [ "python3", "-m", "gunicorn", "-k", "uvicorn.workers.UvicornWorker", "stt:app", "--workers", "1", "-b", "0.0.0.0:3000"]
+CMD [ "python3", "-m", "gunicorn", "-k", "uvicorn.workers.UvicornWorker", "stt:app", "--workers", "4", "-b", "0.0.0.0:3000"]
diff --git a/src/runners/audio_transcriber.py b/src/runners/audio_transcriber.py
index 0310a6e..ce72b4a 100644
--- a/src/runners/audio_transcriber.py
+++ b/src/runners/audio_transcriber.py
@@ -14,6 +14,7 @@
 
 logger = logging.getLogger(__name__)
 
+
 class BatchOutput(BaseModel):
     text: str
     batched_count: int
@@ -23,9 +24,11 @@ class BatchOutput(BaseModel):
 
 
 class WhisperHFRunnable(Runnable):
+
     def __init__(self, model_id: str = "openai/whisper-tiny"):
         device = "cuda:0" if torch.cuda.is_available() else "cpu"
-        torch_dtype = torch.float16 if torch.cuda.is_available() else torch.float32
+        torch_dtype = torch.float16 if torch.cuda.is_available(
+        ) else torch.float32
 
         model = AutoModelForSpeechSeq2Seq.from_pretrained(
             model_id,
@@ -46,9 +49,15 @@ def __init__(self, model_id: str = "openai/whisper-tiny"):
             device=device,
         )
 
-    def forward(self, data: List[bytes]) -> List[BatchOutput]:
+    def forward(self, data: List[any]) -> List[BatchOutput]:
         start = time.time()
-        result = self.pipe(data, batch_size=len(data))
+
+        audios = [d["raw"] for d in data]
+        langs = [d["lang"] for d in data]
+
+        result = self.pipe(audios,
+                           batch_size=len(data),
+                           generate_kwargs={"language": langs})
         logger.debug(result)
         transcribe_time = time.time() - start
         no_punctuation = str.maketrans('', '', string.punctuation)
@@ -59,6 +68,5 @@ def forward(self, data: List[bytes]) -> List[BatchOutput]:
                 merge_audio_time=0,
                 transcribe_time=transcribe_time,
                 restore_time=0,
-            )
-            for r in result
+            ) for r in result
         ]
diff --git a/src/stream_transcriber.py b/src/stream_transcriber.py
index 9a1b764..3450134 100644
--- a/src/stream_transcriber.py
+++ b/src/stream_transcriber.py
@@ -1,8 +1,9 @@
 import torch
 
 from faster_whisper import decode_audio
+from faster_whisper.vad import collect_chunks
 
-from silero_vad import (get_speech_timestamps, load_silero_vad, collect_chunks)
+from silero_vad import (get_speech_timestamps, load_silero_vad)
 
 import numpy as np
 import io
@@ -103,9 +104,7 @@ async def consume(self, stream_data: bytes):
         )
 
         for chunks in speech_timestamps:
-            speech = collect_chunks(
-                chunks, torch.tensor(raw_audio_buffer,
-                                     dtype=torch.float32)).numpy()
+            speech = collect_chunks(raw_audio_buffer, chunks)
             if (not self._speech_audio_buffers
                     or buf2secs(self._speech_audio_buffers[-1]) > 5):
                 self._speech_audio_buffers.append(speech)
diff --git a/src/stt_api.py b/src/stt_api.py
index 34945dd..6229217 100644
--- a/src/stt_api.py
+++ b/src/stt_api.py
@@ -86,6 +86,7 @@ async def handleUpstream(
                                     "raw": np.frombuffer(
                                         stream.get_speech_audio(), dtype=np.float32
                                     ),
+                                    "lang": lang[:2],
                                     "sampling_rate": 16000,
                                 }
                             ]