diff --git a/zaban_backend/app/routes/v1.py b/zaban_backend/app/routes/v1.py
index e5fe6de..ba93d5c 100644
--- a/zaban_backend/app/routes/v1.py
+++ b/zaban_backend/app/routes/v1.py
@@ -9,7 +9,7 @@
 
 from ..services.ai4bharat import Ai4BharatClient
 from ..services.language_detection import get_language_detector
-from ..services.constants import WHISPER_TO_BCP47
+from ..services.constants import WHISPER_TO_BCP47, WHISPER_BEAM_SIZE, WHISPER_BEST_OF
 
 
 router = APIRouter()
@@ -360,15 +360,22 @@ async def stt(
                         temp_file_path = temp_file.name
                     
                     try:
-                        # Transcribe
-                        result = whisper_model.transcribe(
-                            temp_file_path,
-                            language=lang[:2] if lang and len(lang) >= 2 else None,
-                            task="transcribe"
-                        )
+                        # Transcribe with improved auto language detection: condition_on_previous_text=False,
+                        # temperature=0, and beam_size for stable, deterministic language decode.
+                        lang_arg = lang[:2] if lang and len(lang) >= 2 else None
+                        transcribe_kw = {
+                            "language": lang_arg,
+                            "task": "transcribe",
+                        }
+                        if lang_arg is None:
+                            transcribe_kw["condition_on_previous_text"] = False
+                            transcribe_kw["temperature"] = 0
+                            transcribe_kw["beam_size"] = WHISPER_BEAM_SIZE
+                            transcribe_kw["best_of"] = WHISPER_BEST_OF
+                        result = whisper_model.transcribe(temp_file_path, **transcribe_kw)
                         
-                        # Get detected language
-                        detected_lang = result.get("language", lang or "unknown")
+                        # Get detected language from decoding result (same as reference: getattr(info, "language", None) or "en")
+                        detected_lang = result.get("language") or lang or "en"
                         detected_prob = None
                         
                         # Map to BCP-47
diff --git a/zaban_backend/app/services/faster_whisper_stt.py b/zaban_backend/app/services/faster_whisper_stt.py
index 8d4599c..b82eabc 100644
--- a/zaban_backend/app/services/faster_whisper_stt.py
+++ b/zaban_backend/app/services/faster_whisper_stt.py
@@ -191,6 +191,15 @@ async def transcribe(
                 "task": task,
                 "verbose": False,
             }
+            # Improve auto language detection accuracy (same approach as reference + best practices):
+            # - Do not condition on previous text so detection is not biased by prior context.
+            # - Use temperature=0 for deterministic decoding so language detection is stable.
+            # - Use beam search when auto-detecting for more consistent language decode.
+            if lang_arg is None:
+                transcribe_kw["condition_on_previous_text"] = False
+                transcribe_kw["temperature"] = 0
+                transcribe_kw["beam_size"] = WHISPER_BEAM_SIZE
+                transcribe_kw["best_of"] = WHISPER_BEST_OF
             # Add beam search options for translation to improve quality
             if translate_to_english:
                 transcribe_kw["beam_size"] = WHISPER_BEAM_SIZE
@@ -219,6 +228,7 @@ async def transcribe(
                 for s in raw_segments
             ]
             full_text = (result.get("text") or "").strip()
+            # Language from decoding result (same as reference: getattr(info, "language", None) or "en")
             detected_lang = result.get("language") or lang_arg or "en"
             bcp47_lang = self.WHISPER_TO_BCP47.get(detected_lang, f"{detected_lang}_Latn")