Superluminal time advance of a complex audio signal

There has been much recent interest in the study of superluminal pulse propagation; however, all previous findings have been extremely limited, only observing superluminal group velocities for simple Gaussian-like pulses. We now report the observation of a superluminal time advance for a complex, broadband signal. Such an advance causes all frequency components and envelopes to appear to exit a circuit 0.078±0.004ms before entering it. Although this may seem counterintuitive, the results are not in conflict with relativistic causality and could lead to many useful devices.