The Pendulum swings: From the use of the term ‘Project’ to the use of the term ‘Topic’

Let us now consider the various speech organs and their role during the process of phonation. Before we go on any further, let us quickly remark that ordinarily, there are no such things as speech organs. This is because what you can see in the above diagram is a representation of organs whose primary functions are rather biological in nature: digestive, respiratory, etc. However, now that we

have made that remark, we want you, all the same, to realise that the so-called speech organs are an adoption of biologically based organs of the human anatomy. Now let us consider what these speech organs are and how they are used in the speech sound production process.

3.3.1 THE CATEGORIES OF THE ORGANS

Now let us consider the different categories for describing the speech organs.

Let us begin by saying that the organs can be categorised into three. These categories include:

1. The lungs and the tracheal (sub-glottalic wind – pipe) 2. The larynx and the vocal cords (source of sound energy) 3. Pharynx, oral cavity, nasal cavity (supra-glottalic resonators) We are now going to consider their activities in stages.

3.3.1.1. The Sub-glottal Stage

Now let us consider the role of the lungs and the trachea in the process of phonation. We want you to realise that the lungs produce the air that is very much needed for the production of speech. You should realise that the sounds are produced during the respiratory phase of expiratory. In other words, you should note that it is the egressive pulmonic air stream that is used for the production of speech sounds. Note that this egressive pulmonary air passes through the pulmonary alveoli, through the bronchi, through the tracheal tube up to the larynx.

3.3.1.2. The Glottalic Stage

Now let us consider what happens at the level of the larynx and the vocal cords.

The Larynx, you should know, can be visualised as a slit formed by two muscles covered with mucous membrane, lying side by side, known as the vocal folds (or vocal bands or vocal cords). You should also note that the space between the vocal cords is known as the glottis. You should realise that during normal respiration the glottis is open.

However, you should realise that during phonation the glottis assumes a closed position along its medium line. Please take note that the pressure of the pulmonary air separates the vocal cords, which close again and reopen once again. It is important for you to note that it is the vibrating movement of the cords or vocal folds while in contact with the pulmonary air escaping from the lungs that in turn sets this air vibrating thereby creating voice also known as laryngeal energy. We want you to note, this stage that the egressive pulmonic air stream is now in a transformed form as the energy necessary for the production of the speech sound.

3.3.1.3. The post-glottalic stage

Now let us consider what happens next after the energy has been supplied by the contact of the air stream and the vocal cords in the larynx. The post-glottalic stage, you should realise, is characterised by the entry of the airstream into the region of the articulators. You should note that the entry point is the pharynx, one of the supra-glottalic resonateurs. We want you to realise that it is at this entry point that 2 factors will determine the quality of the speech sound.

The two factors, you should note, are the articulators employed and the degree of narrowing between them.

Let us also emphasise that at the point of entry into the pharynx, the state of the velum will go a long way into determining whether the sound is going to be oral or nasal.

Let us briefly explain further that from the pharynx the pulmonic air stream may enter only the mouth or both the mouth and the nasal cavity. You will do well to realise that either of these options will depend on the state of the velum, this membranous part of the roof of the mouth, known also as the soft palate.

The important thing you should know, at this juncture, is that because of the membranic nature of the velum, it can be lifted and drawn back by muscles.

Note, that if this happens the entrance to the nasal cavity is blocked and in that case, an egressive air stream can only enter the mouth.

This is what is known as the raised state or velic closure.

Now remember we are still talking about the post-glottalic stage in the physical activities of the process of phonation. We now want you to realise that these is yet another possible position for the velum. Now, let us consider that at other times the velum may hang down inertly (i.e. in its lowered state or velic opening). Note that if this happens the egressive air escapes through the nasal cavity as well as the mouth.

From what we have said so far, we want you to realise that if the velum is raised, oral sounds result, in which case air enters only the mouth. Example: [s]

as in the French word si. You should also realise that if the velum is lowered, air enters the nasal cavity as well. We want to say that if air escapes through both the mouth and the nostrils, nasalized sounds are produced. Example: [oe]

as in the French word un, meaning one. More of these details will be treated in our very next unit.