When you sample an audio signal at 10Hz, the bandwidth of the signal must be no more than 5Hz. Blowing on the mic or clapping will generate much higher frequency components than 5Hz. For example, think about what happens when you clap. The duration of the clap could be quite a bit less than 1/10th of a second, in which case you sampling is unlikely to even detect it. If you want to react to something as abrupt as a clap, get rid of the running average altogether.
Pete