In order to learn more about guitar tuning and improve their ability to do so, 'gschoppe' has created a guitar tuner that not only creates the matching sounds for each string - it also strobes an LED at the matching frequency. The reason for this is:
The strobe causes the apparent speed of motion of the string to decrease as the user approaches the correct frequency. as the the string gets closer to tuned, the string's vibration will happen in visible pulses of speed and apparent lethargy, which slow as the tuning improves. These variations in speed should coincide with the frequency of audible "beats" when beat tuning.