The circuit we are going to discuss here is a four siren sound generator using UM3561 IC which is a  low power CMOS IC. The four different sounds can be produced by pressing the switches S1, S2 and S3.  The circuit can be used for any type of  sound generation requirements, for example you can use it 

as tone generator, alarm circuit, siren circuit etc. The circuit is quite simple using only seven components and a 3V battery due to which it is ideal for many low voltage applications. The IC can drive a pheizo directly without using any amplication stage. For driving a 8 ohm speaker we have used a single transistor amplifier in figure 1. If more amplification required then use the circuit mentioned in figure 2 which is using a lm386 amplifier for further amplification of sound. The circuit mentioned in figure 2 is using a 3V zener diode for voltage regulation which will step down 9V to 3V because UM3561 IC can not be opreated above  3V DC.

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UM3561 Four Siren Sound Generator Circuit
Figure 1
Figure 2