Amazing.  This would open the sound file in text mode.  Fixed.
SF bug  #446219.
diff --git a/Lib/sndhdr.py b/Lib/sndhdr.py
index 29f0760..df2ccf1 100644
--- a/Lib/sndhdr.py
+++ b/Lib/sndhdr.py
@@ -40,7 +40,7 @@
 
 def whathdr(filename):
     """Recognize sound headers"""
-    f = open(filename, 'r')
+    f = open(filename, 'rb')
     h = f.read(512)
     for tf in tests:
         res = tf(h, f)