Noise is an unwanted electrical signal which distorts the original signal. Noise is present everywhere if there is some finite temperature. All types of noise should be minimsed. Here in this circuit we are trying to deomonstrate the noise signal present around us. If we touch the base of the transistor with our hand, then we can see that the LED starts blinking. Clearly there must be some voltge arising at the base as soon as we touch it, this is the noise present in our body. It is in form of voltage and it is in the range of micro volts.