ANATOMY AND PHYSIOLOGY OF SPEECH
Introduction
The anatomy and physiology of speech and language in simple terms refers to how speech is produced and the various parts involved in its production and the functions of those parts in speech production. In order for a voice to be produced, several ligaments are involved and several muscles are involved in production of sound (Ladefoged and Maddieson 1996). In this case study, we will take a simple word: ‘bumpy’. In analyzing this word we will get to know the various muscles and ligaments and where these muscles are attached to and what role they play in producing each sound in the word ‘bumpy’.
The word ‘bumpy’ has five letters and each letter has a different sound.-/b/, /u/, /m/, /p/, /y/ (Ladefoged and Maddieson 1996). The analysis will be in three steps as follows:
Respiration
This is the simply inhalation and exhalation. in order for sound to be produced, air must be present so that it can be vibrated in order for sound to be made.
Muscles involved in inspiration
The diaphragm is one of the muscles which are involved in inhalation or aspiration. In considering the sound /b/, the diaphragm originates from the tip of the sternum. All fibers insert into a central tendon which is the aponeurosis of the diaphragm, the function of the diaphragm is to draw the central tendon down and forward and this is what enlarges the chest cavity vertically. The diaphragm muscles are the ones which expand the chest cavity. Other muscles include; The external intercostals which run from the lip to the lower borders of the ribs to strengthen the chest wall. The external intercostals are attached to the fibers hence can raise the chest cavity during inhalation. Others are the pectoralis major muscles which attach to the front of the medial half of the clavicle. These pectoralis muscles insert at the greater tubercle of the humerus and their main function is adducting the humerus and also draws the scapula interiorly and inferiorly (Ladeford and Madiesson 1996).
Muscles involved in exhalation of air through the larynx are involved in decreasing the volume of the chest cavity. They include: Internal intercostals which are attached to the front limits of the intercostal spaces. Temporalis muscles originate from the whole temporal fossa. The main role of this muscle is to raise the mandible. Boyle’s law is useful in explaining respiration. The law states that at constant temperature, the volume of a gas will be inversely proportional to the pressure. in the same way, in breathing, the pressure inside the lungs is greater than outside therefore, air is present in the lungs outside through diffusion so as to balance the atmospheric pressure, just like in Boyl’es law (Ladeford and Madiesson 1996).
Voicing
Voicing is caused by vocal cords held close together so that air passes through them and makes them vibrate. The voicing parameters specify if the vocal cords are vibrating or not. Sound is generated in the larynx. This is where adjustments of both pitch and volume are made. The muscles involved in voicing are: Those involved in abducting the vocal cords are the iterarytenoid muscles which bring the posterior ends of the vocal folds together by moving the arytenoid cartilages together (Ladeford and Madiesson 1996). In production of voiceless sounds, the posterior cricoarytenoid muscles separate the arytenoid cartilages so that the vocal folds are abducted.
Muscles which elevate the larynx include Posterior belly of the digastrics, which are attached to the mastoid and function to draw the hyoid bone superiorly and backwards.
Stylohyoid muscles originate from the styloid and insert in the greater cornu of the hyoid bone. Muscles that lower the larynx include; Omohyoid-which originates from the upper border of the scapula and its role, is to lower the larynx, sternohoid-attached to the back surface of the manubrium of the sternum. it helps in pulling the larynx forward by drawing back the hyoid bone. Thyrohoid muscle originates from the thyroid cartilage. It plays a function in rising and lowering the pitch. This is done by elevating the thyroid cartilage after it lowers the hyoid bone (Ladeford and Madiesson 1996).
The opening and closing of the vocal folds can be explained with the following theories: Myoelasticity and the Bernoulli principle in the following way; when the vocal cords come together by being pulled together by the interarytenoid muscles, and pressure is applied to them, they tend to remain closed until a point where the applied pressure is enough to separate or open them allowing air to escape. Hence the pressure is decreased to a level which is low enough for the folds to close again The Bernoulli principle argues that when air is flowing through the glottis and the folds are held closed, a push-pull effect is felt on the vocal fold tissues. The push occurs in glottal closing whereas the pull is experienced during the glottal opening by the posterior cricoarytenoid muscles. This movement of closing and opening and closing of the muscles results in vibrating of the vocal folds resulting in sound being produced (Madiesson 2003).
Articulation
Articulation is well expressed in terms of where articulation occurs and the manner of articulation present. The place of articulation is most evident in consonants because generally, in production of consonant sounds, there is a considerable amount of obstruction. As for the case of vowels, part of the tongue moves closer to the roof of the mouth but there is still enough space and hence it is hard to exactly pinpoint the location of obstruction. Due to this fact, vowels are described by the height of the tongue (Ladeford and Madiesson 1996). In this case word; bumpy, the place of articulation of each sound is: /b/ sound is articulated in the bilabial. Here when producing the sound /b/, both lips come together and separate suddenly producing a kind of explosive sound. The vocal cords come together so that the mouth cavity is completely shut off from the lungs. the larynx is pulled down and the size of the mouth cavity increases(but the amount of air inside doesn’t change) and the pressure inside the mouth is lower as compared to that outside, then the lips come together and separate suddenly making an ingressive sound-in our case /b/ sound. This /b/ sound is a plosive in terms of manner of articulation.
The /u/ sound which is a vowel is a low back unrounded vowel. The lips separate and the tongue are pulled slightly backwards but it is not elevated, it lies in the middle of the mouth (Ladeford and Madiesson 1996).
The /m/ sound is articulated at the bilabial. In terms of manner of articulation, it is a nasal. This is produced in the velum. The muscles involved in raising the velum are the Laveter Veli Palatani which is attached to the apex of the temporal bone and the medial wall of the Eustachian tube and tensor veli muscles attached at the sphenoid bone and the lateral wall of the Eustachian tube.The lips come together with the tongue centrally stationed inside the mouth. The /p/ sound is also articulated at the same place as /b/ sound explained above. The sound /y/ is a voiceless one and it’s produced as a vowel sound /I/.the lips are parted and the tongue is between the teeth (Ladeford and Madiesson 1996)
Conclusion
In conclusion, after the analysis and research provided above, it is evident that although producing sound in simple terms is very easy, the actual activities involved to make the sound are somewhat surprising, but when we talk, we do not notice as this activities are fast and cause no strain or energy use. I have learned the various ligaments and muscles involved in sound production and how sound is produced. During the analysis, it was easy and fun to research as we are humans and all one has to do is speaking and analyzes each voice.
References
Ladefoged, P. &Maddieson, I. (1996). The Sounds of the World’s Languages Oxford: Blackwell
