Reactions to alerting sounds such as short bangs, whistles, horns, buzzers and marbles rolling on a glass plate are used to stimulate facial grimaces.
A more positive response may be produced by using a loud voice to call their name. Pitching your voice one octave above normal may be followed by opening their eyes and / or looking toward you. This response is inconsistent and a lack of a response does not mean that the person is unable to function within ACL 1.0.