audio cable   

Typically a stranded copper conductor in a rubber jacket with continuous copper or aluminum, stranded or foil shield.  One conductor per channel; stereo cables will often share shield. In some applications there is a separate ground cable, though often the shield will be used as ground.  Jacket thickness and flexibility will depend on application: typically thick and flexible for microphone cable or guitar cords, thinner for installations where the cable will not be moved. Conductor size ranges from very small - no. 24 - 30 (as in earphone cable) to large (no. 18 - 24) guitar and mic cable.  For comparison, standard lamp cord is no. 16 - 18 while cable used to plug in heaters might be no. 12 or no. 14. Speaker cable is generally unshielded.  Long cable runs will attenuate high frequencies.  High fidelity systems designers tend to use as thick a conductor as possible for speaker cable, the idea being that this will minimize any conductive loss. No. 2 - 8 are not uncommon sizes - close to the diameter of an adult little finger!
Mono and stereo audio cable with foil shield and one/two conductors respectively.