توضیحات:

At first, select 'RUN' or 'SWIM' or 'SKATE'.
Then push 'START/STOP' button.

After 3-5 seconds(length is random),

RUN: 'Set' => interval((length is random) => 'BANG'
SWIM: 'Take your marks' => interval((length is random) => 'BANG'
SKATE: 'Ready' => interval((length is random) => 'BANG'

After the sound, push 'START/STOP' button as soon as possible.

When red 'F' appears, it's false start.

If you feel difference between the sound and counter start, push 'DELAY' and change number.