patch 7.4.793
Problem:    Can't specify when not to ring the bell.
Solution:   Add the 'belloff' option. (Christian Brabandt)
diff --git a/src/spell.c b/src/spell.c
index 80a7d18..5d9c0cc 100644
--- a/src/spell.c
+++ b/src/spell.c
@@ -10201,7 +10201,7 @@
 	 * a multi-line selection. */
 	if (curwin->w_cursor.lnum != VIsual.lnum)
 	{
-	    vim_beep();
+	    vim_beep(BO_SPELL);
 	    return;
 	}
 	badlen = (int)curwin->w_cursor.col - (int)VIsual.col;