Have you ever walked out to check the mail or to a neighbor's house and heard an odd little buzzing noise when you approached a power line or transformer? Did it make you worry that something may be wrong, or were you just a little confused about why it was making noise? The truth is: it is a very commonly heard noise that is always there. This steady droning or vibration is called "mains hum," and often, it draws attention of small animals, who may creep up and investigate if you do not protect your lines. The science behind what makes power lines buzz is quite interesting to humans too!