1. Respiration:
* Lungs: The lungs provide the airflow necessary to produce sound.
* Diaphragm: The diaphragm, a large muscle under the lungs, contracts to pull air into the lungs and relaxes to expel air.
2. Phonation:
* Vocal folds (cords): Located in the larynx (voice box), the vocal folds are two small, muscular folds that vibrate as air passes through them.
* Varying vocal fold tension: By adjusting the tension and length of the vocal folds, we can change the pitch of our voice.
* Glottis: The space between the vocal folds. The glottis can be open (for breathing), closed (for phonation), or partially closed (for whispering).
3. Articulation:
* Articulators: These are the structures in the mouth and throat that modify the airflow to produce different speech sounds.
* Lips: Used for sounds like "p," "b," and "m."
* Teeth: Used for sounds like "f," "v," and "th."
* Tongue: The most versatile articulator, used to create a variety of sounds by moving around the mouth, touching the palate, teeth, or lips.
* Palate: The hard palate (roof of the mouth) and soft palate (velum) help shape the airflow for different sounds.
* Mandible (jaw): The jaw moves up and down to open and close the mouth, affecting the positioning of the tongue and other articulators.
4. The Nervous System:
* Brain: The brain controls all aspects of speech production, from planning the message to coordinating the movement of muscles.
* Motor cortex: Responsible for sending signals to the muscles involved in speech.
* Sensory feedback: The brain receives feedback from the muscles, ears, and other senses to refine and adjust speech production.
How the process works:
1. The brain plans the message and sends signals to the motor cortex.
2. The diaphragm and other muscles contract to expel air from the lungs.
3. The air passes through the vocal folds, causing them to vibrate and produce sound.
4. The articulators modify the airflow, creating different speech sounds.
5. The sensory feedback helps the brain adjust and refine the speech production process.
Examples of how different articulations create different sounds:
* Stops: By completely blocking the airflow with the lips (for "p" and "b") or the tongue (for "t," "d," and "k"), we create stop consonants.
* Fricatives: By partially blocking the airflow, we create fricatives like "f," "v," "s," and "z."
* Vowels: Vowels are created by shaping the mouth and tongue in different ways, allowing the air to flow freely.
The coordinated effort of all these systems allows us to produce the complex sounds of human speech.