Can I run electrical cable and sound cable in the same conduit?

If you can avoid it, you should not run high voltage and low voltage lines in parallel. They should be separated and should intersect at right angles when they need to cross paths.

You will likely get some interference, but perhaps you won't notice it. No harm in trying.

You really want to keep these separate in a high quality audio setup, as you will get interference...especially through a sub.

I would even recommend routing the cables in entirely different directions if at all possible to minimise mains hum. Is there no other route for them? As an example, my mains wiring is in the walls, so where possible I have my audio wiring in the floor or above the ceilings.

If you absolutely can't avoid running them together, get yourself a cable that has a decent screen and make sure it is earthed.

According to NEC 300.3(C)(1), you can only run the speaker cable in the same enclosure as a higher-voltage circuit if the insulation of the speaker cable is rated for the voltage of the higher-voltage circuit.

NEC 2008 300.3(C) Conductors of Different Systems

(1) 600 Volts, Nominal, or Less. Conductors of ac and dc circuits, rated 600 volts, nominal, or less, shall be permitted to occupy the same equipment wiring enclosure, cable, or raceway. All conductors shall have an insulation rating equal to at least the maximum circuit voltage applied to any conductor within the enclosure, cable, or raceway.

…

The current induced in the speaker wire will not be noticed. If it were an input cable it would be different. Speakers wires are after the amplifier so the interference will not get amplified. The only issue is being sure the insulation on the speaker wire is rated for the higher voltage in the AC line.