I think you are going about your lower loop the wrong way. First, the inner while loop will run infinitely fast eating up CPU cycles. Second, the timing of the lower loop will be affected by the time it takes the person to clap along with the other code in that loop. There is no synchronization between the upper loop and lower loop.
I think you should use an event structure to detect when the person hits the clap button. I would use perhaps either a notifier or rendezvous to help synchronize the code between the upper and lower loops. Perhaps capture the millisecond timer up top when the ding is sent and capture the millisecond timer down bottom in the event structure when the person hits the clap button. Pass one to the other (notifier, single element queue, ) and compare the values.
