This circuit produces a wailing or siren sound that gradually increases and decreases in frequency as the 100u charges and discharges when the push-button is pressed and released. In other words, the circuit is not automatic. You need to press the button and release it to produce the up/down sound.
source :
http://www.talkingelectronics.com.au/projects/200TrCcts/200TrCcts.html