Thank you for your post.
If the sound wasn't there previously, we'll need to determine what has changed.
Create a new database file with one field, and make that field a pop-up. Enter one record. Do you still get the beep? If so, then I would uninstall and reinstall FileMaker Pro. If there is no beep, then return to your original file, remove the field and add a new copy of the field to the layout. Do you still get the beep? If not, then the field on the layout may have become corrupt. If you still get the beep, then create a new layout and add that same field. Access the field and see if you get a beep. If so, the original layout may be corrupt. You may want to consider copying the items from the original layout and paste them into a new layout (do not duplicate the layout).
Please keep me updated with any progress.