What Does it Mean to Sound a Color?

"You sound white!" What exactly does that mean?

I've been doing radio for over 10 years, and during that time, I've had a number of people to tell me that when they first heard me, they thought I was white. I never really understood what they meant, but I just let it pass.

However, something happened to me today that made me question all of this "sounding like a color/race." So, tell me.... What does it mean to "sound white?" Does that mean to speak with grammatically correct sentences? Is it a matter of enunciation? Is it having a vocabulary that extends beyond a certain limit? Using a word that is in an unabridged dictionary but maybe not the little red Webster? Or perhaps the use of a synonym that more accurately describes what I'm trying to articulate rather than the simplest term?
Tell me! What does it mean to sound white?

Better yet, what does it mean to sound black? Am I supposed to sound ignorant as if an "Uhhhh" goes between each word? Am I not supposed to be able to say exactly what I mean without taking long to process my thoughts? Or is it a matter of not omitting particular letters from certain words?

Make no mistakes about it, I speak differently depending on to whom I'm speaking. The way I talk with my sister is not going to be the same way I talk to my coworker, and the way I talk with a coworker is not going to be the same way I talk to a client. Some call it being "fake." I call it being multifaceted and adaptable. The difference between the two is a matter of composition. If I bought a pair of knee-length boots and forced them to turn down to shin-length simply for the comfort of my leg and they don't even look right, I'm forcing them to be something they're not. However, if I took a pair of knee-length boots that are designed to turn down and become a different style, I'm simply adapting to create a different look. They're the same pair of boots, though!
Why is it that we classify a person as fake for adapting to different audiences? That doesn't make sense to me. I've never downplayed my African heritage. Heck, I even rock an afro most days of the week. I guess I sound like I have a weave down my back too, right?
On the contrary, I've also had someone to tell me, "You just sound like you would be tall, dark, and slim." I just smiled and said, "Surprise! I'm none of the three!" What I really wanted to say is, "You 'bout the ignantest mutha--....."

*sigh* Woosah, Jade! Woosah!

Now, tell me how you sound tall? Anybody care to share how you sound a height?
Sound dark? Wanna explain that? I'm not getting it. How do you sound a color?
Sound slim? How? Because I'm not snoring while I'm wide awake? Oh..... Wait a minute. There just may be something to that.

Seriously, though, how do sounds and physical characteristics go together?