2. Suppose you yell in a canyon. You hear the echo of your voice 0.8 seconds later with an amplitude 5% as loud. But, that will echo back again from your side, so you will hear another echo 0.8 seconds later that is, in turn 5% as loud as the first echo. This repeats, with each subsequent echo getting software. Write a transfer equation for a filter that simulates this echo digitally.