Exercise 1-5:

Four Main Reasons for Intonation
Depending on the situation, a word may be stressed for any of the following reasons:
New Information Opinion Contrast and the word "Can't"
1. New Information
It sounds like rain.
Rain is the new information.
It's the most important word in that sentence and you could replace everything else with duh-duh-duh.
Duh-duh-duh rain will still let you get your point across.

Repeat:

Duh-duh-duh rain
It sounds like rain.
Make rain very musical and put it on two notes:
ray-ayn.
Duh-duh-duh ray-ayn
It sounds like ray-ayn.
2. Opinion
It sounds like rain,
but I don't think it is.
In this case,
intonation makes the meaning the opposite of what the words say:
It looks like a diamond, but I think it's a zircon.
It smells like Chanel, but at that price, it's a knock-off.
It feels like...
It tastes like...
These examples all give the impression that you mean the opposite of what your senses tell you.
Practice the intonation difference between new information and opinion:
It sounds like rain. (It's rain.)
It sounds like rain, (but it's not.)
3. Contrast
He likes rain, but he hates snow.
Like and hate are contrasted and are the stronger words in the sentence.
4. Can't
It can't rain when there're no clouds.
Contractions (shouldn't, wouldn't) and negatives (no, not, never) are important words since they totally negate the meaning of a sentence, but they are not usually stressed.
Can't is the exception.