Sound, of course, comprises a range of frequencies, each of which requires the appropriate phase difference for this effect to work. Fortunately, the principle can be understood equally simply for arbitrary signals: our phase shift is actually a delay, sufficient to cancel out that with which simultaneous sounds would arrive at the right ear, together with an inversion (multiplication by −1). Sound from the left channel therefore reaches the right ear via both loudspeakers at the same time, but with opposite signs, cancelling out
identically. The right channel is then added, processed in the same way with a delay and inversion before it is fed to the left-hand loudspeaker. The result is that the left ear is positioned at a node for the right channel, and the right ear at a node for the left channel.