diff --git a/shell_command/shell_command.py b/shell_command/shell_command.py
index 2c8c3ac..830b68b 100755
--- a/shell_command/shell_command.py
+++ b/shell_command/shell_command.py
@@ -223,7 +223,7 @@
     def append_normalisation_filter(self):
         """Append a normalisation audio filter to the complex filter."""
         if (self.has_audio):
-            self.append_filter("[aconc] dynaudnorm=r=0.25:f=10:b=y [anorm]")
+            self.append_filter("[aconc] dynaudnorm=r=0.25:f=10:b=1 [anorm]")
     
     def append_concat_filter(self, frame_type, segments=[]):
         """Append a concat filter to the filters list"""