Suprasegmentals

A suprasegmental is a vocal effect that extends over more than one sound segment in an utterance, such as pitch, duration, or loudness. The suprasegmentals refer to circumstance of sound production beyond and over consonant and vowels. English is a stressed timed language. It means, at least one syllable in an english word is stressed and therefore has principal pitch,duration, or loudness as opposed to the rest of the syllable in the word.
The suprasegmentals also provide information in the comprehension. Process in longer sequences of speech sounds. Pitch plays an importantrole in determining the syntatic and semantic consequences of a phrase or sentence. Different pitch patterns in the phrase may evoke different perceptions in the meaning of the phrase.

Example: Jane write a letter
If syllables at the end of the phrase are longer in duration than at the beginning, the speaker may intend to state an emphasis that Jane write a letter, not a novel. And than, if the syllables at the beginning are louder than the end, we may think Jane who write a letter, not other people.

When pitch behaves in a form of pitch contour of the phrase or sentence, we call it intonation. Intonation help us process a variety of meanings.

Source taken from:

http://fuckyeahpolyglot.tumblr.com/post/41945080643/learn-the-international-phonetic-alphabet