It was the way the speaker said the words rather than the words he selected that upset the audience.

Can someone dissect this whole sentence and tell me which clause is doing what and what is the part of speech of each?
I gave it a shot below:

the way = first part of compound subjective complement
(that) the speaker said the words = relative clause modifying THE WAY
rather than =

the words = second part of subjective complement
(that) he selected =  relative clause modifying THE WORDS

that upset the audience = relative clause modifying one of the subjective complements, but in this case THE WAY THE SPEAKER SAID THE WORDS

The original question I had to answer was is the cluase "that upset the audience" a noun clause or relative clause?
I'm pretty sure it's a relative clause.

Also the pronoun "It" is just throwing me off.  Can someone explain the function of "It" here?

Okay, I think "It" is referring to "the way the speaker said the words."

Thanks so much in advance.  Yes, I used to love sentence diagramming.

Please correct or add anything you wish to help me.

The original question I had to answer was is the cluase "that upset the audience" a noun clause or relative clause? I'm pretty sure it's a relative clause.

Yes, it is, but it's not a common garden variety of relative clause because it is generated by a cleft construction.

Also the pronoun "It" is just throwing me off.  Can someone explain the function of "It" here?

It's an obligatory element (dummy "it") in the cleft construction.

The cleft construction requires it and a (singular) form of be at the beginning and a cleft-construction relative clause at the end.  The so-called 'highlighted element' occurs between.

Compare:

The noise frightens the cat.
It is the noise that frightens the cat.

The book the teacher read delighted the children.
It was the book the teacher read that delighted the children.

The way the speaker said the words upset the audience.
It was the way the speaker said the words that upset the audience.

(rather than can be analyzed as a complex preposition like instead of.)

Unfortunately, the analysis of the sentence by naming the part of speech of each word does absolutely nothing to reveal the true structure of the sentence.

See also Post:262425.

CJ