Continuant

Try to hold out the sound [s] as in sad as long as you can. Then see how long you can hold out the sound [t] as in turtle. You can probably hold out the [s] as long as you want, but you can't sustain the [t] at all. That's because [s] is an example of a continuant, and [t] is a non-continuant.

Continuants don't block air from moving through the mouth, meaning that they can be sustained for an entire breath. The category of continuants is useful in linguistics, especially in the fields of phonetics, phonology, and Computational Linguistics.

The Meaning of Continuant

A continuant is a sound that allows air to flow out of the mouth, meaning that it can be sustained for a long time.

Continuants include:

• Vowels

• Approximants

• Fricatives

• Trills

You can think of continuants as sounds that let air continue to flow out of the mouth.

All sound classes that are not continuants are called occlusive or simply non-continuants.

You might notice a root word similar to the word close in occlusive. The term occlusive comes from the Latin occludere, which means "to close up." Occlusives include:

• Plosives

• Nasals

• Affricates

Continuants in Linguistics

Grouping continuants into a single category can be useful in the field of linguistics. These are some of the uses for the continuant category in linguistics.

• Phonology: Some language patterns apply only to certain sound classes. The continuant category allows phonologists to develop theories about these patterns.

  • In a phonological Alternation called lenition, sounds categorically become "weaker" or less constricted. This can take the form of replacing non-continuants, like Stops, with continuants, like Fricatives.

• Phonetics: The continuant category helps phoneticians theorize about the human articulation and perception of different sound classes.

  • Continuants are often longer in duration than non-continuants. Categorizing sounds as continuants and non-continuants can help phoneticians test hypotheses related to sound duration.

• Computational Linguistics: Computational linguists work in Natural Language Processing and other fields to train AI in recognizing and producing continuant sounds.

Let's now look at continuants in phonetics.

Continuants in Phonetics

Continuants include four sound classes in phonetics: vowels, fricatives, approximants, and trills.

Vowels

Vowels are the most common continuants. They are usually the longest sounds and the building blocks of syllables.

To simplify this definition, vowels are loud speech sounds that you produce while keeping your mouth mostly open. They can also exist as the main part of a syllable. This is important for distinguishing vowels from approximants: more on that later.

The most important point for the discussion of continuants is that you can't close your mouth when producing a vowel. By definition, then, all vowels are continuants.

Fricatives

Unlike vowels, fricatives place obstacles in the way of the airflow through the vocal tract.

Fricatives include sounds like [f], as in fluff, and [s], as in stuff. When you produce a fricative, you constrict the airflow through the mouth, but you never completely close it off. Like a tire with a hole in its wall, your mouth allows air to quickly pass through a small gap. This creates a static-like sound.

Fig. 1 - When producing a fricative, the mouth lets a constant stream of airflow out of a small constriction—kind of like a leaky tire.

By definition, a fricative requires some amount of air to flow through the mouth. This means that all fricatives are continuants.

Approximants

Approximants are similar to vowels but often shorter. They are classified using vocabulary like laterals, rhotics, liquids, and glides (we'll define these shortly).

When you produce an approximant, you bring the articulators in your vocal tract (like your lips, tongue, and teeth) close together to change the airflow, but not so close that you produce a fricative. Now for the categories of approximants:

Trills

Trills involve a vibration between two articulators in the vocal tract.

The [r] in the Spanish word perro ('dog') is an alveolar trill. Just like with any other continuant, you can hold out a trill as long as you want.

Continuants and Non-Continuants

Every sound category is either continuant [+continuant] or non-continuant [-continuant]. The non-continuant sound categories are plosives, nasals, and Affricates.

Plosives

Plosives are also generally called Stops: they briefly stop air from flowing out of the mouth. Plosives include sounds like [p] as in potato and [d] as in duck.

This definition is the exact opposite of the definition of a continuant. Plosives are always non-continuants.

Nasals

One class of sounds that trips people up is the nasal category. Nasals resemble continuants because they involve an uninterrupted stream of air, but they are actually stops.

Nasals include sounds like [m] as in merry, and [n] as in nose. A nasal sounds like a continuant because it can be sustained for an entire breath. However, a nasal still requires blocking air from flowing out of the mouth. This excludes the nasal from the continuant category.

Fig. 2 - Nasal consonants close off airflow through the mouth but not through the nose. This diagram shows a retroflex nasal.

Affricates

Affricates are hybrid consonants that consist of both a stop and a fricative.

Affricates include sounds like [tʃ] as in child. Since affricates begin with a stop, they require a complete obstruction of airflow through the mouth. This means that affricates are not continuants.

Examples of Continuants

Examples of continuants are present in every human language. These are the continuant categories that appear in English. As a reminder, all vowels, fricatives, approximants, and trills are continuants in any language. You won't find any trills in English, but you will find the other three continuant categories easily.

Vowels in English

Of course, the five letters representing vowels in English are a, e, i, o, u, but the English vocabulary includes many more vowel sounds. Linguists use the symbols in the International Phonetic Alphabet (IPA) to distinguish these vowel sounds in writing. Here are the vowel sounds specifically found in English.

Fricatives in English

Fricatives are sounds like [f] as in fall and [s] as in sand. Here's a list of the fricatives in English, including their IPA symbols, articulatory descriptions, and some example words.

Approximants in English

The English approximant category consists of a lateral, a rhotic, and two glides.

These examples summarize all of the [+continuant] sounds in English. Try listening for continuants and non-continuants in your own dialect: speak normally and pay attention to the number of times that you completely close off airflow from your mouth. You'll start thinking like a phonetician, noticing and observing the mechanics of everyday speech.