Alright, Crayon Boy; in regards to your list . . .
Vocals: Between 100 and 350 you get the meat. Or it could be mud, depending on the singer's range, the song's arrangement, etc. From 350 to 700 can be mud. But it could also be the meat, depending again on the singer and the arrangement. Or it could the warmth, depending on those factors as well as the equipment used.
Somewhere from 800 to 2000 usually lies the tonality. This is where you best distinguish the melody line and the overall quality/personality of the vocalist. This is also where you can get some honk and aggression on some voices.
From 2000 to 4000 lies the articulation. It's also where the voice can sound really nasaly, annoying, piercing, grating, etc. But it's a key frequency range for grittiness, vocal aggression, etc.
From 4000 to 8,000 is a real key range for clarity. That's why you'll notice a lot of people's favorite condensers like the Audio Technicas, Shures, etc. all have this big 'ol boost around 6k. It helps keep them sounding clear and free of mud, etc.
The disadvantage to this range is it's also where most voices, particularly male voices articulate their consonants and sibilances -- so boosting this range can often be a double-edged sword.
8,000 to 12,000 -- Air on most male voices or low female voices.
12,000 to 14,000 -- Air on most female voices and/or higher male voices.
Air meaning more a sense of sheen / shine. Kind of an intangible quality -- hard to describe. But very commonly boosted in radio pop vocals, power balads, etc. "Breathiness" might also be a fitting description.
Electric guitar: 2-3 khz is crunch, 600-1100 is honk, 200-400=mud / warmth . . . and lower than 200 is meat for metalish and/or industrial - type guitar.
Anything over 4 khz is mostly annoying amp buzz, static, etc. Anything under 70 hz is probably rumble, hum, or other unnecessary junk.
