Answer:
To begin with there is a source of sound which is an oscillator which can have many different wave forms which include saw, square, triangle and sine. Then there is the filter section, there are 3 different types of filter which are high pass, low pass and band pass, the most common of which is the low pass. Which according to the amount will filter out the low parts of the frequency. Band and high pass do the same except they filter out the high and a specified band. Low frequency oscillators have the ability to modulate pitch, filter frequency and others. You than press a key and according to the setting explained above a certain noise comes out.