diff --git a/vigilancia/voz.py b/vigilancia/voz.py
index 78f402f..132f8dd 100644
--- a/vigilancia/voz.py
+++ b/vigilancia/voz.py
@@ -156,37 +156,37 @@ def _esperar_fin(cast, url, timeout=120):
 
 
 def _generar_pitido():
-    """Genera una sirena estilo Proteccion Civil (wail) si no existe."""
+    """Genera sirena estilo Proteccion Civil (wail). Usa solo math (sin numpy)."""
+    import math, struct
     ruta = os.path.join(MEDIA_DIR, "pitido_emergencia.wav")
     if os.path.exists(ruta):
         return ruta
     try:
-        import numpy as np
-        import wave as _wave
-
         os.makedirs(MEDIA_DIR, exist_ok=True)
         sr = 44100
         dur = config.GOOGLE_TV_PITIDO_SG
-        t = np.linspace(0, dur, int(sr * dur), endpoint=False)
-        if config.GOOGLE_TV_PITIDO_ESTILO == "wail":
-            # wail defensa civil: sube 400->1000 y baja en ciclos de ~4s
-            periodo = 4.0
-            fase = (t % periodo) / periodo
-            freq = 400 + 600 * (1 - abs(2 * fase - 1))
-        else:
-            freq = 500 + 400 * np.abs(np.sin(2 * np.pi * 0.5 * t))
-        fase = 2 * np.pi * np.cumsum(freq) / sr
-        y = 0.8 * np.sin(fase)
-        fade = min(0.3, dur / 4)
-        n_fade = int(fade * sr)
-        y[:n_fade] *= np.linspace(0, 1, n_fade)
-        y[-n_fade:] *= np.linspace(1, 0, n_fade)
-        data = (y * 32767).astype(np.int16)
-        with _wave.open(ruta, "w") as w:
-            w.setnchannels(1)
-            w.setsampwidth(2)
-            w.setframerate(sr)
-            w.writeframes(data.tobytes())
+        n = int(sr * dur)
+        periodo = 4.0
+        nfade = min(int(0.3 * sr), n // 4)
+        phase = 0.0
+        samples = []
+        for i in range(n):
+            t = i / sr
+            if config.GOOGLE_TV_PITIDO_ESTILO == "wail":
+                f = (t % periodo) / periodo
+                freq = 400 + 600 * (1 - abs(2 * f - 1))
+            else:
+                freq = 500 + 400 * abs(math.sin(2 * math.pi * 0.5 * t))
+            phase += 2 * math.pi * freq / sr
+            y = 0.8 * math.sin(phase)
+            if i < nfade: y *= i / nfade
+            elif i > n - nfade: y *= (n - i) / nfade
+            samples.append(struct.pack("<h", max(-32768, min(32767, int(y * 32767)))))
+        import wave as _wave
+        with open(ruta, "wb") as f:
+            with _wave.open(f, "w") as w:
+                w.setnchannels(1); w.setsampwidth(2); w.setframerate(sr)
+                w.writeframes(b"".join(samples))
     except Exception as e:
         print(f"[Voz] No se pudo generar el pitido: {e}")
     return ruta