From where does the sound come from when two charged objects meet in real life? I am sure all of us have played with rubbing things and producing static electricity and when I was charging my comb by rubbing it on my hair and watching it attracting a small piece of paper, I heard a very feeble noise just like an electric buzz sound. I could feel the electron "cloud" all around the comb and the paper  it I could find no reason as to why a sound should be produced. From where is that sound coming from?
 A: Almost all objects around us are electrically neutral, meaning they have no excess in negative/positive charges. When we use a plastic comb on our hair, a very small amount of negative charges start accumulating on the comb, making it negatively charged. It is important to note that it is not the friction caused by combing your hair that leads to such charge accumulation, instead it is simply related to maximizing the contact surface between comb-hair, making the charge exchange more likely to occur. This is of course all in simple words.
Now as for the sounds you hear, they are called electric sparks, which results from the discharge of two initially charged objects. The electric field created by the two, ionizes the air, creating ions from air molecules, which in turn becomes a conductive channel (temporarily), this channel is necessary for the discharge (exchange of charges until neutralization) to occur. Finally a spark is formed when the electric field strength exceeds the dielectric strength (polarizability of air) of air. The discharge in the conductive channel raises the temperature of the surrounding air. Since the discharge takes so little time to go from one region to another, the heated air has no time to expand. The heated air is compressed, raising the air's pressure to much higher values than the normal atmospheric pressure. The sudden expansion of the compressed air creates a loud burst, which we call a spark.
On wikipedia there's also a good bit of explanation. Just google electric spark for further sources and explanations.
