Noise generator 2 frequency with ic 555

This is a simple noise generator circuit. An IC Timer IC 555 is a number of major equipment. Small circuit. Suitable for various test circuits.
Operation of the circuit is when the power supply to the circuit. It will give birth to high frequency by using a circuit IC1 to a multi-state Devices Bill Brett Foster. The frequency with which R1, C1 and C2. The frequency will be out in three legs. And will be expanded with the IC2 output pin out of 5 in order to drive the speakers. The high-frequency sound. But when the switch S1, capacitor.
C1, which continue to cycle in a manner parallel to the C2 value higher density. IC1 will give birth to low-frequency out of pin 3 to IC2 then drive the speakers. This circuit can cause the audio source has two frequency.