is there any reason for using the notice command why not just use echo -a $nick $+ ( $+ $chan $+ ) $1-. it will do the same job and only send to the currently active window.
Code:

on 1:TEXT:*quig*:#: {
  if ($chan == $active) return
  /echo -a $nick $+ ( $+ $chan $+ ) $1-
  beep 5 100
}