Intonation gives the same sentence multiple meanings. Variation in pitch indicates the speaker's attitudes and emotions, and highlights or focuses on an expression.

Emphasis on a certain word is important for the right outcome. I've noticed many students disregarding intonation in their presenting––it often requires unlearning to learn.

For example, our voice typically rises at the end of the sentence when asking a question. The fall-rise intonation pattern makes the questions sound more polite and hedges some confidence in case of rejection or mistake.

We all do this without thinking about it.

But some people I've tutored use fall-rise intonation for more sentences than just their questions. They make non-questions sound like questions. This is not only confusing, distracting, and monotonous, but alters the meaning of the message.

A simple mistake, but an impactful one.

One of my favourite examples of intonation's impact on meaning is one I read in How To Be Confident by James Smith. If you were to really emphasise on the highlighted text, it gives the same words a new meaning:

I didn't say we should kill him. = Someone else said we should kill him.

I didn't say we should kill him. = I am denying saying it.

I didn't say we should kill him. = I implied it/whispered it/wrote it down.

I didn't say we should kill him. = I said someone else should kill him/you should kill him, etc.

I didn't say we should kill him. = I said we shouldn't kill him/we must kill him, etc.

I didn't say we should kill him. = I said we should take him to dinner/take care of him/send him on a holiday.

I didn't say we should kill him. = We should kill someone else.