 The most common mode of human communication is the use of speech, which by means of a simple description can be broken down to three main events. The production of sounds, the analysis of the sound wave, and the perception of sounds. And these three events taken together are referred to as the speech chain, which constitutes the focus of this lecture. Speech needs a stream of air to carry sounds. But how does that really work? Well, let's just think for the moment about how we hear sounds. Why can you hear me right now? We cannot see any link between us. Well, the sound that you hear is carried by the air. The movements I make with my vocal organs cause vibrations in the air. And these travel across to the microphone, which I have here, as a series of invisible movements called sound waves. Ignoring the digital conversion process that is necessary for the production of this video, the sound waves then leave your loudspeakers or your headphones as sound waves. And enter your ears where they activate a network of tiny bones and cells to eventually enable you to hear me. These steps are the central parts of the speech chain and constitute the main branches of the field called phonetics, which looks at human speech from three distinct but interdependent viewpoints. One viewpoint is referred to as articulatory phonetics, which studies how speech sounds are produced. Auditory phonetics studies the way in which humans perceive sounds. An acoustic phonetics, the third branch, studies the physical properties of speech sounds. The names of these three branches all begin with an A. Alternatively, you could use a P and associate them with the following terms. Articulatory phonetics, the production of speech sounds. Auditory phonetics, the perception of speech sounds. An acoustic phonetics, the physics of physical properties of speech sounds. Let us now look at the main goals of these sub-branches. Articulatory phonetics investigates how speech sounds are produced. This involves some basic understanding of the anatomy of speech. For example, of the lungs which produce the necessary energy in form of a stream of air. The larynx that serves as a modifier to the airstream and is responsible for phonation. And the vocal tract which modifies and modulates the airstream by means of several articulators. Furthermore, since all speech sounds involve some sort of air, articulatory phonetics also discusses the central airstream mechanisms involved in producing the types of airstreams used for speech. The combination of anatomical properties and the respective airstream allows us to precisely define all speech sounds or so-called segments that are used in natural language, where two types of sound can be differentiated. Vowels and consonants. Whereas consonants are produced with some kind of obstruction in the vocal tract, vowels allow an almost free passage of air. Here we have two examples. The vowel E involves an almost free air passage. And the consonant K in the environment of akka produces an obstruction to the airstream, as we will see right now. Akka. Again? Akka. Vowels and consonants are the basic segments of speech. Together they form syllables, larger units and eventually utterances. Superimposed on the segments are a number of additional features known as suprasegmental features. The most important ones are stress, loudness, pitch and length. Let us now look at the second branch. Auditory phonetics. Auditory phonetics investigates the processes underlying human speech perception. The starting point for any auditory analysis of speech is the study of the human hearing system. That is the anatomy and physiology of the ear and the brain. Since the hearing system cannot react to all features present in a sound wave, it is essential to determine what we perceive and how we perceive it. This enormously complex field is referred to as speech perception. And this area is not only of interest to phonetics, but it is also the province of experimental psychology. Let us finally turn to acoustic phonetics. That is the study of the physical properties of the speech signal. This includes the physical characteristics of human speech, such as the frequency patterns involved, the analysis of friction noise, etc. There are numerous factors that complicate the straightforward analysis of the speech signal. For example, background noise, anatomical and physiological differences between speakers and so on and so forth. These and other aspects contributing to the overall speech signals are also studied under the heading of acoustic phonetics. Well, let us summarize. After this short overview of the field of phonetics with its main branches, we should have an idea about the central goals of the field. These goals, ranging from speech anatomy to the physical analysis of speech, will be discussed in detail in further e-lectures. Until then, thanks for your attention.