Speed up normalization if numpy is avaliable

IPython/lib/display.py

@@ -103,6 +103,11 b' class Audio(DisplayObject):'
         import struct
         from io import BytesIO
         import wave
+        try:
+            import numpy as np
+            data = np.array(data,dtype=float)
+            scaled = list(np.int16(data/np.max(np.abs(data))*32767))
+        except ImportError:
         maxabsvalue = float(max(map(abs,data)))
         scaled = map(lambda x: int(x/maxabsvalue*32767), data)
         fp = BytesIO()