I am trying to understand audio amplifiers. I keep a running across words to the effect that a particular resistor "develops" a signal. I have no idea what this means! Help?

 

That's a bit of an odd way to phrase it, although there are some contexts in which it would be pretty natural.

When you pass a current through a resistor, there will be a corresponding voltage across it. In some circuits you take several signals that are in the form of currents and sum them together and then send the total current through a resistor in order to get a voltage that is proportional to the sum of the individual signals. You can do similar things to get signals that are proportional to the difference of two signals, as well.

 

If you were reading about the common emitter BJT amplifier , then when you have a collector resistor and the transistor starts conducting (it's resistance goes very low) then there is a current flowing through the collector resistor which means that a voltage generated across the resistor .
Think of the collector resistor and the transistor as a voltage divider (that's what it really is )

 

Excellent, Shagus. Thank you so much.