For speech to occur, air must be forced up out of the lungs, up the trachea, and into the vocal tract. 

The components of speech production are 

• the lungs

• the larynx ("voice box") containing the vocal folds and the glottis

• the vocal tract with the nasal and oral cavities

1. The lungs

Speech requires some sort of air source. We produce a majority of speech sounds by forcing air upwards from the lungs, an action that is used in normal breathing. 

Of course just forcing air out of the lungs does not result in speech sounds. After all, when we want to blow out candles on a birthday cake, we force air out of the lungs, but this is not speech. To produce a speech, sound the outward moving airstream must be modified by manipulation of the larynx and articulators in the oral and nasal cavities. The ways in which the airstream is modified is the focus on this module.

The central organs involved in the production of speech sounds include: the lungs, larynx, and vocal tract (the oral cavity, nasal cavity, and pharynx). While each of these is used for normal physiological processes involved in breathing and eating, they also function in the production of speech. 

2. The larynx ("voice box") containing the vocal folds and the glottis

The larynx, more commonly known as the voice box or the Adam's apple, is crucial in the production and differentiation of speech sounds. The larynx is located at exactly the point where the throat divides between the trachea (the windpipe), which leads to the lungs, and the esophagus (the tube that carries food or drink to the stomach).

Over the larynx is a flap called the epiglottis that closes off the trachea when we swallow. This prevents the passage of food into the lungs. When the epiglottis is folded back out of the way, the parts of the larynx that are involved in speech production can be seen.

The Vocal Folds

There are two thin sheets of tissue that stretch in a V-shaped fashion from the front to the back of the larynx. These are called the vocal folds. (You'll often hear vocal "cords," which is doesn't accurately convey the way the muscle works.) The space between the vocal folds is known as the glottis. The vocal folds can be positioned in different ways to create speech sounds. 

Air passes through the vocal folds. If the vocal folds are open and air passes unobstructed, the vocal folds do not vibrate. Sounds produced this way are called voiceless. But if the vocal folds are held together and tense and air doesn't pass unobstructed, the sounds produced this way are call voiced. 

It's important to understand what voicing is.

Voicing is an important concept because it helps us to describe how consonant sounds are made. Understanding voicing can help you to sound like a native speaker as you learn languages. If you plan to be a language teacher, coach, or therapist, voicing will become one of the tools you'll use to help your students, patients, and clients with their speech.

3. The vocal tract with the nasal and oral cavities

When the air passes up through the vocal folds, it is expelled through the mouth (oral cavity). Here is a cross view of a human head, looking to the left.

The tongue, lips, teeth, and various regions of the mouth constitute points of articulation in the oral cavity. We'll explore more about sound production in the oral and nasal cavities in an upcoming lesson.

In oral sounds most air is expelled via the oral cavity (mouth). Typically the velum is raised at the back of the mouth to block the passage of air into the nasal cavity.

In nasal sounds, on the other hand, the velum is lowered, to allow airflow through the nasal cavity. In English, nasal consonants are accompanied by the blocking of airflow through the oral cavity.

Notice that the movements of your tongue and lips are identical in the (a) and (b) examples of (1-3). The only difference is that the velum is raised in the (a) examples and lowered in the (b) examples.