 Phonetics looks at human speech from three distinct but interdependent viewpoints. Articulatory phonetics studies how speech sounds are produced. Auditory phonetics studies the way in which humans perceive speech sounds, and acoustic phonetics studies the physical properties of speech. Now the names of these branches all use an initial letter A. Alternatively you could use a P and associate these branches with speech production, auditory phonetics with the perception of speech, and acoustic phonetics with the physics of speech. So here you have your initial characters P. A good way to remember these disciplines. Let us look at the main goals of these branches first. Articulatory phonetics investigates how speech sounds are produced. For example, speech sounds such as these vowels here, E, or to use a second one, the vowel U, or let us take consonants such as this one as in P versus, well let us take a more exotic one, this one here as in A. Now the production and the description of these segments of speech involves some basic understanding of speech anatomy. For example, some knowledge about the lungs, and the question how the lungs produce the necessary energy in form of a stream of air. Or let us look at the larynx next. So here is the larynx which serves as a modifier to the air stream and is responsible for phonation. Well at last but not least, the vocal tract itself. Now here is the vocal tract. And the vocal tract modifies and modulates the air stream by means of several articulators. Let us mark those articulators which are actively involved in the modification of the air stream that is those four active articulators. Now furthermore, since all these speech sounds involve some sort of air, we have to look at the central air stream mechanisms because, so you see, without air stream nothing will happen. So let us look at the air stream mechanisms in some detail. Now whereas in English all speech sounds are initiated by outward going aggressive air from the lungs, other languages may use additional ways of producing an air stream. The following air stream mechanisms can theoretically be used in human speech. Well most languages, in fact all languages, use speech sounds that are produced with aggressive that is outward going pulmonic i.e. from the lungs coming air. So aggressive pulmonic air as in pa for example. Now you could use this ingressively that is inward directed in situations when you sob or cry such as pa. So this was an ingressive pulmonic air stream but you will certainly agree that this is a rather exceptional situation so let us put this in brackets and mark it with a minus. The glottalic aggressive air stream which is produced here in the larynx, of course exists in many languages. It can be used aggressively in sounds such as ta or ta and it can be used ingressively as in sounds like ga or ga. So here we have the ingressive glottalic air stream and the aggressive one coming from the glottis. And finally we have the velaric air stream which cannot be used aggressively. It is produced here in the vocal tract itself but in an ingressive form it can be used in sounds such as and here I like this one a. The symbol is nice isn't it for a kiss it's this phonetic symbol. So it can be used. The combination of anatomical properties and the respective air stream allows us to precisely define all speech sounds that are used in natural language where two types can be differentiated vowels and consonants. Now vowels allow an almost free passage of air through the vocal tract. The example that you can see here to my right is e and you see the air stream passes freely through the vocal tract and the lips have to be spread. Consonants by contrast involve some sort of obstruction to the air stream in the vocal tract. Here we have the example of ka as in a ka again a ka and you see during the consonantal posture some sort of closure has been created. Now vowels and consonants are the basic segments of speech just like the notes are basic segments in music. Together vowels and consonants form syllables, they form larger units and eventually utterances. Superimposed on the segments are a number of additional features known as suprasegmental or prosodic features. They do not characterize a single segment but a succession of segments. The most important suprasegmental features are stress, loudness, pitch and length and then we also have aspects such as secondary articulation. Now in music to draw the parallel again suprasegmental features would be something like crescendo or something like diminuendo or forte to name a few. The two remaining branches of phonetics are often treated in an interdisciplinary way by means of a combination with psychology, anatomy, acoustics, physiology to name a few. Let us briefly discuss them. Auditory phonetics investigates the processes underlying human speech perception. The starting point for an 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. Well if you want to find out more about this field consult our e-lecture pre-lexical processing one. Acoustic phonetics and here you see some machines studies 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 me and you and many more. These and other aspects contribute to the overall speech signal and are studied under the heading of acoustic phonetics. This e-lecture is just an overview of the field. In future e-lectures about phonetics we will concentrate on articulatory phonetics and discuss the details of segmental and suprasegmental phonetics. We will look at consonants, at vowels we will discuss aspects of stress, pitch, loudness and will illustrate our findings with numerous examples from the language index of the virtual linguistics campus. By the way in the toolbox here is your toolbox. You have permanent free access to our interactive consonant and vowel charts and many more. So join us. Ok that's it for now. See you again in one of our e-lectures on phonetics and if you like on the virtual linguistics campus.