Default volume of the bell is 0.

config.def.h

@@ -41,7 +41,7 @@ static unsigned int blinktimeout = 800;
  * bell volume. It must be a value between -100 and 100. Use 0 for disabling
  * it
  */
-static int bellvolume = 1;
+static int bellvolume = 0;
 
 /* TERM value */
 static char termname[] = "st-256color";