 After a phonetic plan has been generated it is converted into a string of pronounceable segments. This string is forwarded to the articulation mechanisms that is to the lungs, to the larynx and to the vocal tract and is controlled by the central nervous system. This is our most complex motor skill. It involves numerous parts of our body and is coordinated by a variety of muscles and nerves. This process can be subdivided into two central aspects. Articulation on the one hand, control on the other. Let us focus on articulation in the following. Well we have three central mechanisms that are responsible for the production of speech. First we have our respiratory system or respiration where the lungs produce the necessary energy in form of a stream of air. The second mechanism is referred to as phonation where the larynx serves as a modifier to the airstream and is responsible for all sorts of sound sources. And finally the resonation mechanism is the component where the vocal tract modifies and modulates the airstream by means of several articulators. Let's look at respiration first. Now before any sound can be produced at all there has to be some form of energy. In speech this energy takes the form of a stream of air normally coming from the lungs. Here are the lungs. And this airstream is referred to as pulmonic air. The whole respiratory system is contained within the chest or thorax. There we have the lungs which I've already pointed out. They provide the reservoir for pulmonic airflow in speech. The lungs are connected to the trachea. So this is the trachea or alternatively you can refer to it as winged pipe. And then we have two bronchial tubes which join at the base of the trachea. So here they are the two tubes. Well at the lower end of the thoracic cavity we find the dome-shaped diaphragm and at the upper end we find the larynx. And the larynx is the main organ that is responsible for phonation. Now the primary biological function of the larynx is to act as a valve by closing off air from the lungs or preventing foreign substances from entering the trachea. The larynx consists of a number of cartilages which are interconnected by complex joints and which move about these joints by means of muscular and ligamental force. Let's point out the most important of these in the following. Here are three views of the larynx. So this view looks at the larynx from the front. This is a view from behind this so-called posterior view. And here we're looking at the larynx from above so it's the top view. Well in looking at the larynx we have a number of important elements. For example we have the hyoid bone which can only be seen from the front. Now this horseshoe-shaped hyoid bone serves as the basis for the tongue. It's a very important bone also for considering the evolution of human language. The epiglottis. So this is hyoid. Let's write down hyoid first of all. Now the epiglottis that's this part here. Epiglottis which can only be seen from behind. Now the epiglottis is attached to the anterior part of the thyroid cartilage. Thyroid cartilage which is basically this one. Thyroid. It is attached to the anterior part of the thyroid cartilage and closes off the larynx during swallowing. In speech it is involved in the production of some consonants. Then quite important are the, well let's mark them in black here because this is blue, the arytenoids or arytenoid cartilages. Now they are connected to the vocal folds which you can see here. These are the vocal folds or also referred to as vocal cords. The movement of the arytenoids, this sort of movement, has a direct influence on the tension of the vocal cords. Now the vocal cords themselves constitute the basic sound sorts of speech and the gap between them, this gap here, is referred to as the glottis. In speech production the larynx modifies the airflow from the lungs in such a way as to produce an acoustic signal. The results are various types of phonation. Let's look at them now. Well as I said the most important effect for speech is the production of an audible vibration, a buzzing sound known as voice or vibration. Each pulse of vibration of the glottis of the vocal folds, each opening and closing movement represents a single sound. The number of cycles per second depends on age and sex. Average male voices like mine which is relatively high at the moment because I'm telling you something, vibrate at around 120 to 180 cycles per second. Women's voices average 220 cycles per second. So 220 times the vocal cords come together on average in women's voices. Now depending on the type of laryngeal action different modes of phonation can be distinguished. I will try to illustrate them in the following. Now if there's no voice then the glottis is open and we can breathe relatively steadily like this. Whenever we produce normal voice like I'm doing at the moment the vocal folds vibrate so the arytenoids control the vocal folds. Now here's our next example, whisper. This is an example of whisper. Now whisper requires a far greater constriction than the voiceless setting of the glottis and is generally achieved by adducting the vocal cords while maintaining an opening between the arytenoids. The next example is breathy voice. Well this is an example of breathy voice where normal vocal cord vibration is accompanied by some continuous turbulent airflow on top of it. Here is another variant, creaky voice. So this is an example of creaky voice, very low creaky voice. This is a phonation mode characterized by a low frequency of vibration of vocal cords with a very low opening quotient and often some irregularity in periodicity. Here's a very interesting one. This is an example of falsetto. Well as you could hear falsetto is a phonation mode where the vocal folds and vocal cords are stretched longitudinally so that they become relatively thin in cross section. Well as already said falsetto is primarily heard as phonatory setting in singing. Do you remember the Bee Gees? Saturday Night Fever Night Fever. Okay now let's continue with resonation the final component. Once the air passes through the trachea and the glottis it enters a long tubular structure known as the vocal tract. So this here is then the passage could also involve the nose, the vocal tract. Here the airstream is affected by the action of several mobile organs, the active articulators which are actively involved in the production of speech sounds. So where are the active articulators? Well of course we have the lips which are mobile, the uvula is mobile, then of course the glottis as we've already seen that is mobile and the tongue. Don't tell me that the teeth are active articulators? Well if you did I would say okay in the case of the third teeth the third set of teeth yes but normally they're not mobile they don't move. The active articulators are supported by a set of passive articulators all the other organs or locations in the vocal tract which are passively involved in the production of speech sounds but do not move. Well as a result of articulation audible speech that is a bundle of resonance frequencies is produced and these bundles serve as input to the human perception mechanism. How they can be analyzed will be discussed in the nature of the input signal part one.