In trying to find out what kind of instrument the voice is, we need to take a look at how instruments are divided into families. The traditional orchestra is divided into four families - Brass, Woodwinds, Strings and Percussion. But acoustic scientists (scientists who work with sound) divide instruments into five types, depending on how the instrument vibrates:

Chordophones - in which strings vibrate - like violins, cellos, etc. Aerophones - instruments that work with air - like flutes, clarinets, pipe organs and trumpets Membranophones - instruments that work with thin stretched skins, like drums Idiophones - things where what vibrates is a solid thing, like xylophones, rhythm sticks, bells and gongs Electrophones, where electricity creates the sound - like synthesizers, radios, tvs

Of course, there are combinations of the above types. The kazoo, for example is a combination of membranophone (the buzzing paper is a membrane) and an aerophone (you have to blow in it to make it work).

The voice starts with an air pump - the lungs.

The air comes up through your trachea up to the thing in your throat called the larynx. Put your hand on your throat and find the big bony thing at the front often called the adam's apple - that is the larynx. Inside the larynx are two flexible vibrating things called vocal cords. Actually "cords" is not really a good name, because they are not string at all, but rather flexible stretchy material more like a stretched piece of balloon.

These two stretchy things are what vibrate. How much your vocal cords are stretched makes your voice higher and lower - the looser your vocal cords, the lower the sound, and the tighter, the higher.

Then as the sound goes up into your mouth, the shape of your mouth (and the shape of your sinus cavities in your face and nose) change the sound even more, to create a wonderful flexible instrument capable of sounding like Louis Armstrong or Brittany Spears or Bobby McFerrin.

Sing the word "Aaahhhh" on the lowest note you can reach and hold the note. As you hold the note, try now to close your mouth a bit more - as you do it, you'll notice that your sung note will change to more of an "Owwww" sound. When you have the "Owwww" sound, touch the tip of your tongue to the roof of your mouth - you may have to relax the inside of your mouth a bit to do this.

Now, holding the tip of your tongue to the roof of your mouth and singing the low note, try slowly opening and closing your lips a bit - you should notice that a strange sound is now coming from your mouth - a combination of the low sung note and a odd, high "wheer" sound. Move your lips about more and you'll discover that you can make the note lower as your mouth is more closed and higher as your mouth is more open.