Acoustic representations

The sounds of speech are made by changes to air pressure that are caused by airflow through the vocal tract. As the air moves, it causes perturbations, which the ear picks up. The ear converts physical movements in the air into electrical signals that are sent to the brain, which is where processing of other kinds (such as detecting meaningful units like sounds, words, sentences and so on) occurs.

Technology makes it possible to convert these changes of air pressure into pictures; and being static and unchanging, these pictures allow us to examine more of the detail of talk as it happened. This kind of phonetics is known as acoustic phonetics, and we use some acoustic representations to show some of the details of talk. The aim here is to enable you to understand that there is a connection between articulation and acoustics. There are two main kinds of acoustic representations we will use: waveforms and spectrograms. We will approach these representations as pictures which can show us particular aspects of speech and as a useful complementary tool to transcriptions.