"When my sink drains I hear gurgling sounds."

While your sink or tub is draining, you hear gurgling noise coming from your pipes. Rest assured, it is not gremlins. What you are hearing is air trapped in the pipes. The presence of air in the pipes signifies the need for a vent in the pipe. Also, if you have a garbage disposal it could be clogged with some sediment and air is trapped behind the clog. Do you notice the gurgling after using your kitchen sink? If you do not know how to install a vent, then it would be best to hire a plumber. A plumber would be able to determine the source of the problem and where a vent is needed.