The main functions of intonation

Intonation
In linguistics, intonation is the variation of pitch when speaking.
Intonation and stress are two main elements of linguistic prosody.
Intonation is a part of suprasegmental phonology.
Intonation helps to recognize the language that you hear in the same way as the melody of a song helps to recognize the song that you hear.

Key components of Intonation
Intonation is based on several key components:
Pitch,
Sentence stress,
Rhythm.

Pitch
Pitch is the degree of height of our voice in speech.
Normal speaking pitch is at midlevel.
Intonation is formed by certain pitch changes, characteristic of a given language.

Sentence stress
Sentence stress makes the utterance understandable to the listener by making the important words in the sentence stressed, clear and higher in pitch and by shortening and obscuring the unstressed words.
Sentence stress provides rhythm in connected speech.

An important feature of English intonation
is the use of an intonational accent (and extra stress) to mark the focus of a sentence. Normally this focus accent goes on the last major word of the sentence.

Functions of intonation
Attitudinal functions
Accentual functions
Grammatical functions
Discourse functions

ATTITUDINAL FUNCTIONS
Allow us to express emotions: finality, confidence, interest, surprise, doubt, joy, pain, irony, etc.

How to express a certain attitude:
1-Different voice qualities for different attitudes
2-Different pitch range in different ways
3-Different keys: high key, mid key or low key
4-One may use different facial expressions, gestures and body movements

Four Types of Attitudinal Intonation
1- Fall Intonation
2- Rise Intonation
3- Fall-rise intonation
4- Rise-fall intonation

ACCENTUAL FUNCTIONS
When it is said that intonation has accentual function, it implies that the placement of stress is somewhat determined by intonation.

GRAMMATICAL FUNCTIONS
The listener is better able to recognize the grammar and syntax structure of what is being said by using the information contained in the intonation. For example such things as:
A - The placement of boundaries between phrases, clauses and sentences.
B - The difference between questions and statements.

THE DISCOURSE FUNCTIONS OF INTONATION
Intonation can signal to the listener what is to be taken as “new” information and what is already “given”.
It can indicate when the speaker is indicating some sort of contrast or link with material in another tone unit.
In conversation it can convey to the listener what kind of response is being expected from him.