The Physiology of Speech Production

Speech is produced when air is expelled from the lungs to the bodily systems and structures that create sound waves. The quality of the sounds produced depends on the force and volume of air pushed from the lungs to the vocal cords. The following processes are involved in speech production.


When you inhale, you let in air to your lungs, which will then be expelled out to produce sound waves. The diaphragm, which is a muscle located below the ribcage, expands or relaxes when air is let out. From the lungs, the air travels up the trachea or the windpipe, through the larynx or the voice box, and the vocal cords, producing vibrations and sound waves. Normal respiration produces natural speech. A loud voice is produced when a large volume of air and a great amount of force is used to expel air from the lungs. A soft voice or a whisper, on the other hand, is produced when there is only a small volume of air let out.


Phonation refers to the process of producing sound waves when air is pushed through the vocal cords. When you speak, muscles around the voice box places stress on the vocal cords, which then produces the tone of the voice.


Resonance occurs when the voice is amplified as the sound passes through chambers and structures such as the upper part of the larynx, the throat, the oral and the nasal cavities.


The lips, teeth, tongue, jaw, alveolar ridge, hard and soft palates, nose, and throat all affect the sounds produced. The manner of articulation depends on the positions of these articulators and the shape of the oral cavity. Vowels are produced when the mouth is open without obstructions while consonants are produced when there are obstructions that hinder the air from going out freely. For instance, nasal sounds such as /n/ and /m/ are produced when the mouth is closed and air passes through the nasal cavities. When the point of the tongue touches different points of articulation, such as the hard palate, or the alveolar ridge, the sound produced also differs.