To bi-wire or not to bi-wire?

Biwiring is explained scientifically on the Vandersteen website

A theory is proposed...low frequency high power signals induce noise on high frequency low power signals. It is hardly science though.

Given the low impedances of speaker loads and amplifier outputs it seems unlikely that noise can be induced in speaker wires that would be at all audible.

Of course, there is some ground truth, if you run unshielded line level signal wires next to some AC power cables feeding an airconditioner then it is quite likely you will pick up some noise...but this is because of the very low levels of signal at line level and the fact that termination impedances are around 10K Ohm - meaning that tiny stray induced currents may actually produce audible noise - even allowing you to pick up interference from a radio station or a ham radio perhaps..

A more logical explanation for reported observations may be caused by unecessarily wide bandwidth amplifiers of the sort that amplify flat up to 200 KHz - instabilities in amps of this type (with large amounts of feedback) might be affected by the slight change in cable inductance that biwiring would bring versus a conventional speaker wire. (Why anyone needs an amp flat to 200 KHz for audio reproduction is rather bewildering, however, specifications like this might make a buyer think the amp is "better" than one which rolls off above 20 KHZ - so they sell - the same way that damping factors of 1000 sell...)

This would correspond to steepness of the sound wavefront. A 14KHz tone that is not a sine wave can have a wavefront steepness corresponding to a 20 KHz sine wave. I haven't tried it lately, but supertweeters with response to 40 KHz and higher are audible to some people

Given that the ear drum is a filter that removes high frequencies from the inner ear it is hard to believe that anything above 20 Khz has any bearing at all in an adult. Test have never shown people able to hear at 40 Khz. So whatever they are hearing it is most likely an artifact that is in the band of 20 Hz to 15 KHZ and most likely something around 500 to 5 Khz where our hearing is most discerning.

Once again, like with amplifiers flat to 200 KHz - it seems plausible that the increased bandwidth of certain designs might cause differences to appear in the audible spectrum (amp instability at HF perhaps causing in band artifacts).

Alternatively, band limited devices - such as the use of a metal/ceramic transducers that are band limited and undamped and therefore have ringing problems within the audible range (requires a sharp high Q filter to prevent ringing) might cause phase distortion in the audible range. Like the brick wall filters in early CD's - it was known that the severe high frequency filtering sometimes caused audible artifacts/problems in band. In that sense, a device that has greater bandwidth might have better in band response - due to less artifacts from sharp filters...

In essence, there might be audible differences but the audible differences are most likely in band. This is the way ATC Hypersound technology works....modulated ultrasonic frequencies react with non-linear air particles and produce audible sound - again some mechanism is required ( in this case non linearities in air at 110 db SPL at ultra high frequencies) to make the effect audible. Perhaps a blind or something in your room could act as the non-linear converter.

Musicnoise - with normal hearing, one can hear intensities from 0 dB to 140 dB

Agreed. And how most home systems can be called "Hi-fidelity" when they are limited to maximum SPL of 95 db SPL at the listening position (before compression distortion and other non linearities appear in spades)....well lets just say that is a much bigger mystery than bi-wiring!