Feedback

That’s feedback.  Your computer’s loudspeakers are playing sound into the Audio Dock’s microphone and the Audio Dock is “feeding back” that same signal to your computer’s loudspeakers, which are playing it back to the Audio Dock’s microphone, which is feeding back to…  you get the idea. The horrible whine is the sound of the signal spiraling out of control. The solution is to use the Audio Dock speakers for playback rather than your computer’s speakers, because we’ve calibrated the Audio Dock microphone-speaker system to ensure you won’t get feedback. Simply connect the second of the two supplied 3.5 mm (1/8-inch) cables from your computer’s headphone output to the Audio Dock’s Aux input. You should not experience that horrible whine any longer.