Testing if loudspeakers still work...

[Krist]

I've got a pair of loudspeakers that I'm not sure are still functioning as specified. I don't trust may ears however to find out, as I just might have so used to them that I don't notice.
However, when I play music, and listen close to the speakers I can clears hear sounds coming from the tweeter, and the woofers, but not from the mid range. I do get the impression that there is something going on, in the form of some faint crackling.
I'm not sure however. Is there a way to do an objective test?
I'm thinking along the line of some test tones (can I download a Flac with some test tones somewhere?) combined with some easy spectrum analysis app for the iPhone.
Any suggestions?

 

[j_garcia]

If you replay a particular sequence where you hear crackling, and it is repeatable, then it isn't the speakers. Does it get worse/more frequent as you turn it up louder? I would say it is unusual for the sound to be coming both from the tweeter and bass driver simultaneously and have it be a speaker issue unless both are damaged. Both speakers do this or just one?

 

[Krist]

the thing is that I hear mostly nothing from the mid range. But when I put my ear close to it, it is as if some crackling does come from it.
Maybe I'll need to try it out with different material. But is there something that I can use, like a test tone that should be output by the mid range alone that I can play? I'm not willing to just trust my ears.