A beeping noise, with long pauses in between beeps at first, then shorter and shorter until a continuous beep. . . Could be used like a timebomb i guess.
Minidisc recording of various birds singing in my back yard. Some distant construction noise is also (barely) audible in the background at a few points.
People demonstrating in a political protest, big group of people creating noise by banging pots, pans, and other utensils by some eventual whistling and voices.
Sci-Fi Soundtrack A robot brain, or computer thought process. (hint - it is random complex waves and noise - but different from the other one) - Kevin MacLeod
