When you sing any given pitch, you are producing sound not just on that pitch, but also different overtones as well. That’s one reason why your voice sounds like a voice, not a pure computer-beep sine wave.
Think about what happens if you change the EQ settings on your mixer or your stereo. Even though the notes sung reside within a relatively narrow EQ band, dropping just that band does not remove the voice from the track entirely. You can still hear something like an “echo” of the voice in other frequencies.
Like other musical instruments, the shape of your resonators (lungs, throat, mouth, nasal passages) help determine the overtones you produce. Unlike many other musical instruments, you can change these overtones to some degree by changing the shape of your resonators.
OK, enough technicalities. What does this mean for my singing?
You generally want to keep a good tonal balance no matter whether you are singing low or high notes, whether you are a bass or a soprano.
But I’m a bass singer. Why do I need to worry about high frequencies in my voice?
Yes, of course a bass voice will have more depth than a soprano. And a soprano will have brighter color than a bass. But within their own voices and their own ranges, all notes should keep a good tonal balance. Your voice should not get strident and sharp just because you are singing a high pitch in your range. And it shouldn’t get dark and dull just because you are singing a low note in your range.
Here is a great example of a bass singer, Nils Christian Fossdale, keeping brightness in even his lowest tones, on a Norwegian TV station. (Skip to about 30 or 40 seconds in.)
Even though he hits some wicked low notes, his tone doesn’t get dull and dark. He retains brightness in his voice.
OK… I think I understand. So how do I do it?
One thing you can do is make sure that your larynx stays neutral. It should not drop (lower) for low notes or rise for high notes. Try placing your fingers on your larynx, with one finger over your Adam’s apple. Then sing an octave scale up and down, and see if your larynx rises and falls. If it does, you’re probably changing the shape of your throat and thus changing your tonal balance as you sing higher and lower.
Another thing you can do is make sure to retain a good balance of nasal (pharyngeal) resonance and mouth resonance. Too much focus on mouth resonance, and you can sound dull, dark, or shouty. Too much focus on nasal resonance, and you can sound sharp or strident.
And finally, you can imagine that the notes are not higher or lower, like a ladder, instead they are just spread out horizontally in front of you. Don’t think of low notes as physically “low” or high notes as physically “high.” They’re simply spread out in front of you, in a line parallel to the ground.
(c) 2011 Adrienne Osborn