Hi HarajukuGirl
People usually mean one of two different things when they talk about speaking through their nose.
Firstly, someone may be talking with air (and sound) leaking down their nose. This is what I think of as nasal speaking or singing.
or
Secondly, someone may have a bright, brilliant, twangy voice that is "placed forward" (sorry, singing teacher-speak). This may or may not have air leaking down the nose.
Both are fixable if you think it's a problem. It's easy to find out which one you are doing by testing for the first one (leaking air down the nose) like this:
Speak or sing the word AHH or EEE and hold it for a reasonably long time. With your fingers, gently pinch your nose closed and open a few times. If the sound changes, you are leaking air down your nose. If the sound stays the same, you aren't.
It's as simple as that.
If you ARE leaking air, there's a door at the back of the roof of the mouth that leads into the nose, and it's a little bit open. You need to close it.
If you AREN'T leaking air, then you have a bright voice. You can change it to a darker one if you want to, or keep it bright, or do both (your voice is very flexible). Remember that if you aren't leaking air, then people are telling you to change because THEY don't like the sound of bright voices.
I've got some more info about nasality on my website, and I've also got some downloadable video footage of the nasal port (the door into the nose) filmed from INSIDE the nose - it's fun unless you're squeamish! Check out the Resources/Articles and the Voicebox Videos link on the Vocal Process website at
VOCAL PROCESS for Singing and the Actor Training, Belting and Musical Theatre techniques
Happy speaking!
Performancecoach