First, watch this video of Anne Sullivan describing how she taught Helen Keller how to speak.
2.1.1 Introduction to Phonetics, from Sarah Harmon
So in the video above this video script you see a dialogue between Annie Sullivan and us. She's describing what she did to teach Helen Keller, to speak. Remember Helen Keller was both blind and deaf; so a deaf person normally relies on a primary sign language like ASL couldn't do that because Helen was blind. She had to first teach Helen how to finger spell but with the hands, so that you could do [gestures] the different letters on the hand. She could feel them and then she wanted to learn how to speak so Annie Sullivan taught her how to speak. And I think it's really important to understand what Annie taught her is essentially phonetics articulatory phonetics; that's what she taught her how to do.
Why do we need to study phonetics? Well English is a really great example as to why; you can't just rely on how a language is written in order to know how it is pronounced. Those of you who had to learn English as teenagers or adults, you know this very well, so this is a really great poem by T.S. Watts; I love using it.
"English--As I Know It" by T.S. Watts
I take it you already know
of tough and bough and cough and dough
Other may stumble you, but not you,
on hiccough, thorough, laugh, and through.
Well done! And now you wish, perhaps,
To learn of less familiar traps?
Beware of heard, a dreadful word,
That looks like beard and sounds like bird.
And dead: it’s said like bed, not bead;
For goodness’ sake, don’t call it deed!
Watch out for meat and great and threat.
(They rhyme with suite and straight and debt.)
A moth is not a moth in mother,
Nor both in bother, broth in brother.
And here is not a match for there
Nor dear and fear for bear and pear
And then there’s dose and rose and lose
Just look them up—and goose and choose
And cork and work and card and ward
And font and front and word and sword
And do and go and thwart and cart—
Come, come, I’ve hardly made a start!
A dreadful language? Man alive.
I’d mastered it when I was five!
Certainly with respect to language, if we go just strictly by how a language is written, we're not going to be actually describing how it is pronounced. Some languages are written fairly phonetically but even still how you write down the sound is arbitrary.
There's that word again, and we're going to come back to over and over and over again. So, how do we talk about languages sounds? How do we describe them and how do we produce them? That is the subject of phonetics.