Airstream Mechanism in Speech Production

Airstream Mechanism in Speech Production

Introduction

There are three main constituents of speech production. They include phonation, articulation, and air stream mechanisms. The third component will be discussed. Through the course of this article, an explanation of the concept of air stream mechanisms will be developed. This will be followed by the types of airstream mechanisms in speech production. 

Airstream Mechanism

The airstream mechanism refers to the process by which the vocal tract creates airflow. There is no production of sound in the absence of airstream mechanics.  This is owing to the fact that this mechanism is compulsory for the initiation of sound production – the first part of the process of sound production. 

There are organs that are capable of generating the airstream, and they are referred to as initiators. While there are organs used to initiate sound production in spoken language and they are the diaphragm, the glottis, and the tongue. These organs function by decreasing or increasing the pressure that is used to generate airstreams. This change in pressure corresponds with inward and outward flow of air and is commonly referred to as ingressive and egressive respectively.

Pulmonic Initiation

This refers to the initiation of speech sounds in the lungs.  The majority of the speech sounds in human language fall under pulmonic egressives.  To make a speech sound, it goes without saying that there is a need for airflow. It is the molecules in airflow that vibrate and create sound waves. A good number of speech sounds, not only in the English language but around the world, are made by the contraction of the diaphragm muscles in such a way that air is forced out of the lungs and passed through either the mouth or the nose. All airflow that is initiated in the lungs is referred to as “pulmonic”. Similarly, all airflow out of the lungs is referred to as “egressive pulmonic’ airflow as the term “egressive” refers to “going out.” It is important to note that any stop that is made with a pulmonic airstream that is egressive is referred to as a “plosive.” 

The possibility of airflow being both pulmonic and ingressive must not be ruled out. Ingressive refers to “going in.” Though it is possible, few to no languages make use of this airstream mechanism. This may be due to the fact that airflow that is ingressive fails to permit the vibration of the vocal cords. A good example would be an attempt to pronounce the word “bee” while breathing in. It is difficult to accomplish. On the other hand, egressive airflow is easy to accomplish because a speaker is able to utilize the pressure gotten from their full lungs to command exhalation. 

Glottalic Initiation

This refers to the initiation of airflow to make a speech sound in the upper vocal tract with the use of the glottis or vocal cords.  The glottalic airstream mechanism is the “movement of the pharynx air by the action of the glottis.” Here, an upward movement of the glottis that is closed will subsequently push air out of the mouth. This is as opposed to a downward movement of the glottis that is closed which will ultimately result in the suction of air into the mouth.  

To produce a speech sound initiated in the glottis that is egressive, a sequence must be followed. First, one must lower the glottis and close it (this is commonly referred to as a glottal stop). Then, one must raise it. This builds and constructs an amount of pressure in the upper trachea and oral cavity. “Ejectives” is the name given to egressives that are glottalic by nature. 

To produce a speech sound initiated in the glottis that is ingressive, there is similarly a sequence that must be followed. First, one must raise the glottis and then close it. This is followed by the lowering of the glottis in such a way that there is the creation of suction in the oral cavity and the upper trachea.  “Implosives” is the name given to ingressives that are glottalic by nature. 

Velaric (Lingual) Initiation

This refers to the initiation of airflow to make a speech sound in the oral cavity and does not necessarily require the generation of airflow from the lungs. As an alternative, there is suction to create distinct air pressure. Here, the sound is produced by the closure of two articulation points.  In other words, the velaric airstream mechanism refers to the movement of the air in the mouth by the tongue to produce different speech sounds. 

To produce a speech sound that is a lingual ingressive, one must first close the vocal tract at two points. For example, at the back of the tongue and simultaneously at the front of the tongue or at the lips. This may be referred to as a “coronal “or “bilabial” stop.  This may be either voiced, voiceless or nasalized.

To produce a speech sound that is a lingual egressive, one must make an attempt to reverse the process of producing a lingual ingressive. Thus, one must close off the vocal cavity with the front and back of the tongue, while the middle of the tongue and cheeks inwardly move upward to increase the oral pressure.  The only known use of the lingual egressive as of now is the “bilabial nasal egressive click” in Damien. “Clicks” are made with the velaric airstream, and it refers to a stop that is produced as a result of an airstream that is ingressive in nature.

Airstream Contours

Some clicks in speech production that are complex are considered to have airstream contours. Here, the flow of air changes between the front and the back release. There exist two main attested types of air stream contours. The first is referred to as “Linguo-pulmonic” which occurs where there is a release in the rear which is “uvular obstruent.” The second is referred to as “Linguo-glottalic” which occurs where there is a release in the rear which is an “Ejective.”

Summary

The pulmonic airstream mechanism is an airstream mechanism that is initiated in the lungs (diaphragm) and may be voiced or voiceless. Examples include p, b, t, d, k, and g.

The glottalic airstream mechanism refers to an airstream mechanism that is initiated by the action of the glottis. It may be ingressive, which is usually voiced, or egressive, which is voiceless. 

Lastly, the velaric airstream mechanism refers to an airstream mechanism that is initiated in the oral cavity by the action and/or movement of the tongue. It is ingressive and may be voiced or voiceless.

Conclusion

This paper sought to discuss the airstream mechanisms of sound production. By opening up with an explanation of airstream mechanisms, a foundation for the rest of this article was made. The differentiation of the types of airstream mechanisms by the organ where the air is initiated provided a greater understanding of the concept. It was the aim of this article to discuss the pulmonic, velaric, and glottal airstream mechanisms in such a way that it may easily be understood by anyone reading.

By Soma Wokemba