I've been doing some spectrum analyzer runs on my electric guitar just for fun. Easy plucking gives a frequency bandwidth from about 80Hz to a little over 1kHz when only looking at the fundamentals. But almost all notes have a second order harmonic which actually rises above the fundamental. I think it is something with the metal strings because on my nylon stringed acoustic the fundamental dominates. It doesn't matter if I use a mic held close to the strings or the guitar pickups, the note and it's harmonics look about the same.
So that means my electric guitar has tones going to several thousand Hz when playing clean.
When I add distortion, even slight overdrive, the spectrum is very complex. With hard distortion the harmonics go past 20kHz. Another reason old vinyl recordings of classic rock (as well as everything else) sound so much better than the bandwidth reduced CD.
So to conclude, at least for electric guitar, the frequency spectrum is very wide indeed.
Αυτο ειναι ενα μερος απο την συζητηση σε καποιο σχετικο forum για το θεμα.Θα το βρεις στο παρακατω link.
Ελπιζω να βοηθησα.
http://www.diyaudio.com/forums/showthread/t-59977.html