Redefina "bell_msg" para incluir um literal "^ G". (Ou seja, os dois caracteres carat e Capital-G .)
Na% man_de% manpage:
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).