I managed to replace the audible bell by a visual clue in the active window, but for background windows, can I get an audible bell instead of a visual notification ?
Redefine "bell_msg" to include a literal "^G". (That is, the two characters carat and Capital-G.)
bell_msg [message] When a bell character is sent to a background window, screen displays a notification in the message line. The notification message can be re-defined by this command. Each occurrence of `%' in message is replaced by the num ber of the window to which a bell has been sent, and each occurrence of `^G' is replaced by the definition for bell in your termcap (usually an audible bell).