If you think about a sine wave, it is really showing a point on a moving and rotating circle. So each cycle is 2π radians. By multiplying the frequency in Hertz by 2π, we are converting to ...

Sine-wave speech can be thought of as a sort of auditory illusion, a sensory edge case in which one’s experience has a clear “before” and “after” moment, like going through a one-way door.