You may want to be notified of a key's status while SlowKeys is active. That way you don't have to guess whether you've held the key down long enough for it to be accepted.
There are two check boxes ("pressed" and "accepted") in the Settings window for setting how you want to be notified of a key's status when SlowKeys is in effect. By checking these boxes, you can have your machine beep:
When a key is initially pressed
When the key-press is accepted
Both when the key is first pressed and when the key-press is accepted
Not at all