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How does music "move" down a wire?

Please excuse me for this question if it is dumb. I'm trying to understand how music/sound moves down a wire. (I think) I understand how sound is transmitted through air and that an electrical signal is produced by the source (e.g., stylus in groove) which, after various amplification stages, then 'excites' electrons in the speaker cable.

However, I don't know if different notes (e.g., double bass versus flute) 'excite' the electrons in different ways. That is, do the electrons excited by bass notes move slower than those excited by flute notes? To add complication, music is comprised of many notes played at the same time. Do some electrons move with the bass notes and others with the flute notes, or is it a wave of electrons with various layers of frequency one atop the other?

Would electrons be moving similarly in each wire of a stranded cable (i.e., they would only be excited within the boundaries of that particular wire) as opposed to the electrons moving across the full diameter of the cable?
kencalgary
auxetophone
114 posts
 
You guys are obviously new to this forum thing. "Great Job!" "Excellent Answers, THANKS!!!" Sheesh!!

The whole point here is to attack the opinions of others and prove how intelligent you are, not some idealistic search for the truth. I think the last two administrations proved that the truth doesnt matter, so get with the program;)
heyraz
177 posts
 
How many things does "db" stand for? I can think of two, one is a logarithmic unit of sound intensity, the other can be bought in a pharmacy.
lplayer
28 posts
 
http://www.audiosystemsgroup.com/TransLines-LowFreq.pdf

might be a little complicated for most...but read between the lines.
almarg's avatar
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almarg
9,670 posts
 
Lplayer, thanks for providing the link to that paper, which is excellent IMO.

When I wrote my earlier comments, I hadn't thought of the fact that propagation velocity will slow at low frequencies. However, as can be seen in Figure 2 of the paper, it will still be about 5,000,000 meters per second at 20Hz, meaning that propagation times through cables at that worst case frequency are still utterly insignificant in a home audio system.

For those who don't want to bother with all the technical stuff, IMO the bottom line of the paper is expressed in its last two sentences:
Thus, at audio frequencies, a cable less than 2,000 ft long is no more complicated than its series resistance and parallel capacitance. As the cable becomes longer, or as frequency increases, the cable will BEGIN to behave as a transmission line.
I would add that in a speaker cable, in particular, inductance can also sometimes have audibly significant effects. The focus of the paper is mainly on transmission of line-level signals through coaxial or balanced cables.

Regards,
-- Al
lplayer
28 posts
 
exactly Al.
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