Does it need to distinguish between a clap and a short shout, or just between a clap and normal talking?
If it's the latter, then simply listening for 2 loud sounds wouldn't work, since loud talking could just be constant loud noise.
However, it might work to listen for a loud noise, then for a silence, then a loud noise, then a longer silence, all within a certain period of time from each other. I have a Clapper that plugs into an outlet to control lamps, etc, and it appears to work in this way. (i.e. if I clap, a light turns on at each clap, but if I just say "aaaaaaaaaaaaaaaaa", one light goes on, then turns off.)
This means you can still purposely trigger it by making 2 short shouts, but this probably would not end up being a problem. (and a useful feature if both of your hands are broken)