Overview of the human speech mechanism

The complexity of speech sounds

Human speech is complex, and lay people are not used to describing it in technical ways. On the other hand, many people have some inkling of how to describe music. We could describe the rhythm (where are the beats? what is the tempo?), the melodic structure (what key is it in? what scale does it use? are there recurrent themes?), instrumentation, and so forth. All of these are different aspects of music, and all of them contribute to the totality of what we hear.

Describing speech is a similarly complex task. Speech involves the careful co-ordination of the lips, tongue, vocal folds, breathing and so on. The signal that we perceive as successive sounds arises from skills that we learn over years of our lives, even as our bodies grow and age. In producing even the simplest of speech sounds, we are coordinating a large number things. Phonetics involves something like unpicking the sounds of speech and working out how all the components work together, what they do, and when. It is a bit like hearing a piece of music and working out how the score is constructed.

One problem we face is exactly the interconnectivity of the parts: in a way, we need to know something about everything all of the time. The purpose is to give you an overview of the speech mechanism. The terms and concepts that are introduced here will be developed in more detail later, but understanding even the simplest things about speech is easiest if we have an overview of the whole system: so we will introduce a lot of basic terminology of phonetics.