If your voice goes croaky, does anything happen to your voice box to make it go all croaky?

The way you make sounds with your voice box is that you have these things called vocal chords. These are just flaps of tissue found in your neck just about where that bulge is. That's your voice box. When air rushes out of your lungs past your vocal chords, it makes them vibrate. When they vibrate, a bit like a string on a guitar, they make little vibrations of sound waves, and that's how you talk. When you get a really heavy cold, which is usually caused by a virus, it attacks the cells in your nose and on the back of your throat. This can make a lot of mucus, and the mucus can get onto your vocal chords. When a string has something sticky on it, it doesn't vibrate as well as when you've got a clear string. So when you try and vibrate your vocal chords and they're covered in gloop, they don't vibrate in the way they would normally and make a funny noise. That's why it goes all funny and croaky when you get a cold.