How does music "move" down a wire?

Excellent answers by Elizabeth!

How different would wire lengths have to be for the acute listener to notice a difference in the arrival time in a pair of a stereo signals at the speakers?

Several miles or more, by which point timing differences would of course have long since been swamped by other effects (frequency-dependent signal losses caused by resistance, inductance, capacitance, among many other effects).

Electrical signals (as opposed to individual electrons, whose movement is irrelevant to the question) propagate through wires at roughly 60% to 90% of the speed of light in a vacuum, which in turn is about 186,000 miles per second. If we assume 75% as being typical (the actual number depends mainly on the dielectric constant of the cable's insulation), the corresponding propagation time is about 1.36 nanoseconds per foot of cable. 1.36 nanoseconds is 0.00000000136 seconds.

The speed of sound in room temperature dry air is approximately 1126 feet per second.

Based on the 1.36 ns/foot figure, a 20 foot difference in cable length between the two channels, for example, would result in an arrival time difference at the speakers of 27.2 ns.

Based on the 1126 ft/sec figure for the speed of sound in air, 27.2 ns corresponds to the arrival time difference at the listener's ears that would result from his or her head being 0.00037 inches closer to one speaker than to the other. In other words, not likely to be audible!

Regards,
-- Al

Elizabeth, come clean, you must be a teacher by trade. Well done.

Thanks Elizabeth, that was a great explanation. From your explanation I would guess that connections (e.g., spades) also would affect the wave especially if the connector was a huge hunk of different material? I assume material "density" (or resistance) would impede some frequencies more than others?

Thanks Al, very cool logic. Your analysis would of course hold best in scenario of an anechoic chamber. In the average listening room, reflections and nodes etc. would further diminish any vanishing differences in sound imparted by differences in speaker wire length.

I have fretted about this in certain applications in the past and it has cost me in wasted lengths of speaker wire. I haven't ever noticed a difference in sound with differential lengths of wire, but since I was fretting about everything else, I thought I should worry about this too. Apparently not. Thanks again for your analysis.

I have fretted about this in certain applications in the past and it has cost me in wasted lengths of speaker wire. I haven't ever noticed a difference in sound with differential lengths of wire, but since I was fretting about everything else, I thought I should worry about this too. Apparently not. Thanks again for your analysis.

You're welcome! Keep in mind, though, that my comment only addressed the question of arrival time differences.

If other parameters, such as resistance, inductance, capacitance, and possibly skin effect, are not small enough to be negligible in the longer cable (all of those effects are proportional to length) a length disparity could conceivably have audible consequences.

And of course there is also the practical factor of resale value being less if lengths are unequal.

The likelihood of those effects being audible, btw, besides being dependent on the design and length of the cable, is also highly dependent on speaker impedance, and the variations of speaker impedance with frequency. Everything else being equal, higher speaker impedance can be expected to result in smaller cable effects.

Best regards,
-- Al