will different lengths affect sound

A corollary to Kijanki's good comment is that if the longer cable behaves in a neutral manner in a given system (which is dependent on the impedance characteristics of the speaker as well as on the cable characteristics), the shorter one will too!

One thing is for sure, IMO. Timing differences, which were asked about in the OP, won't matter. Electrical signals propagate through wires at a large fraction of the speed of light in a vacuum (186,000 miles per second) at treble frequencies and higher, and even the slowest propagating audible frequency (20Hz) propagates at more than 3000 miles per second. Since 3000 miles/sec is roughly 15000 times faster than the speed of sound in air, the arrival time difference at the listener's ears resulting from a 10 foot difference in cable length would be the same as the difference that would result from his or her head being 10/15000 = 0.0006 feet closer to one speaker than to the other (and far less than that at mid and treble frequencies). In other words, not likely to be audible!

Regards,
-- Al

PS68, thanks very much. I should further clarify my earlier comment, however. As it appears you realize but others may not, I was not saying that the effects of a considerable difference in speaker cable lengths will necessarily be inaudible. I was saying two things:

1)There will be no audible effects AS A RESULT OF the difference between the two channels in propagation delay/arrival time.

2)If the longer cable is chosen such that it behaves in an essentially neutral manner with the particular speaker and amplifier, the shorter one will also behave in a neutral manner, and therefore they will perform identically.

As you realize, for item (2) to occur the resistance and inductance (actually, inductive reactance) of the longer cable have to be insignificant in relation to speaker impedance at all frequencies that matter, and capacitance has to not be excessively high (in which case it might affect the behavior of the amplifier). Also, it is conceivable that under some circumstances the amplifier may be sensitive to rfi (radio frequency interference) that may be picked up by the cables and enter its feedback loop, if it has one. That pickup would figure to be length sensitive, although of course with essentially no predictability.

Other less readily explainable effects may come into play, as well.

So while I would approach claims of audible effects due to speaker cable length differences with a good deal of skepticism, I would not completely rule out the possibility that they may be perceivable under some circumstances. Especially if the cables are not chosen such that their parameters result in neutral or near-neutral behavior in the particular application.

Best regards,
-- Al