Hearing the audio is fairly normal -- if you plug it into the line in (or line in-mic combined on many laptops) then most operating systems will have it play back.
Static is more likely a signal, pun intended, that you need to turn down the volume on the line in settings (stock windows tends to have it very high), or if you plugged it into a mic one then plug it into the line in (mic, usually a dull red/pink colour if it has one, will tend to supply a bit of power).
Having it charge either from the same PC (can lead to ground loop issues, though should be fairly isolated) or charger (cheapo USB chargers are often electrically noisy little things) might also lead to a hum.
Another thing to note. If the lead itself near another lead, power supply, metal radiator, big power device or similar? If so you might get some induction in it. If you can hold the lead in relatively clear air and it goes away then probably that.