Now that my teenage DS has a deep voice, if he speaks at a certain angle behind my back (quite close and a little off centre to my right) I get an unpleasant sensation like a cold chill or electric shock that runs down my spine. It always makes me jump! 
It happens with other low frequency sounds too, like hair clippers etc.
No one else in my house experiences anything like it. I’ve tried to google to prove it is a thing but all I have come up with is some scratchy thing on YouTube but it isn’t that.
Anyone experience the same thing, or know what it is called?