I have learned a lot from my Behringer DEQ2496 which has a spectrum analizer function, 61 frequency bands, 1/3 octave. The internal wide bandwidth noise signal is a good representation of music, but you can also look at externally generated signals like a sine sweep.
And, after you understand your problem you can fix it with the EQ function. $350 including mic. What a deal!
And, after you understand your problem you can fix it with the EQ function. $350 including mic. What a deal!