Accent Reduction: American Intonation in Sentences

At the sentence level, we stress one word (or syllable of a word) for each thought group.  The typical pattern is to stress the last content word (noun, verb, or adjective) in the thought group. We raise our pitch and lengthen the vowel for the stressed word or syllable.
Listen to these examples:

 I'd like to do that, but I need to go now.

I'm really hungry, let's get sushi tonight.

I didn't have time to finish it yet.

Notice that the overall pitch pattern for each thought group is to rise to the stressed word, then fall off at the end.  When the last word of the thought group is stressed, it rises and falls on the single word, to indicate stress and the end of the thought.  For example:

I told them no.

That's what he wants.

She prefers green.

This standard stress pattern for a declarative sentence (rise in pitch to the most important word, then fall off) will vary when something needs extra emphasis.  Examples might be to change from the standard meaning, to clarify, or for other special emphasis.  Listen the sentences below.  The words are the same, but the meaning changes when the stressed word changes. 

I didn't have any.  (standard pattern)
I didn't have any. (implies someone else did)

We wanted to go. (standard pattern)
We wanted to go. (but we couldn't)

I gave them the report. (standard pattern)
I gave them the report. (implies they are responsible, not me)