Chapter 3: Phonetics

3.7 Signed language articulators

The phonetic units of signed languages

As discussed in Section 3.1, articulatory phonetics is concerned with how the body produces a linguistic signal, regardless of modality. We do not normally want to describe the overall articulation of an entire word in spoken language, so we break it down into phones for easier discussion. So what is the comparable unit for signed languages?

In signed languages, the basic independent meaningful unit, the equivalent of a spoken language word, is generally an individual sign. But signs do not seem to have a direct equivalent of phones. Phones can generally be spoken on their own, separate from any other phones. For example, we can take any of the individual phones in the English word [bɛd] ‘bed’, and say each one separately. It may be awkward, especially for plosives like [b] and [d], but it is not impossible. The independence of phones from words and their ability to be recombined in different ways is a key property of spoken languages.

But the corresponding sign BED in ASL cannot quite be broken down in the same way. For example, no matter what we try to do with our hand, it always exists in some shape and some location. We cannot just blank out the fingers or put the hand in some mysterious null dimension. So if we want to shape the hand in some particular way, we must necessarily do so somewhere, and similarly, if we want to put the hand in some location, we must necessarily also configure the fingers somehow.

This is how the articulatory properties of phones work, too. We cannot make an articulation with the tongue tip and alveolar ridge without also deciding how far apart they are, and we cannot articulate a manner of articulation without choosing an active and passive articulator, and thus, without choosing a place of articulation. That is, properties of phones like place and manner are interdependent, in the same way that the shape of the hand and its location are interdependent. But this is not how phones behave, since phones have independent existence and can be articulated separately from other phones.

So, the units of articulation in signed language that we are concerned about are signs (whole independent words) and the individual articulatory properties of a sign (how various articulators are shaped and moved). There seems to be no intermediate signed language unit that corresponds to spoken language phones (however, see Section 3.10 for discussion of syllables as a kind of intermediate organizational unit that both spoken and signed languages seem to have).

Notation of signs: Linguistic units from spoken languages are often given in italics, with the gloss (meaning) in single quotes, while signs from signed languages are often given in all capitals or small capitals. So we would write bed when referring to the English word, lit ‘bed’ when referring to the equivalent French word, and BED or BED when referring to the equivalent sign in ASL.

There is some variation in how to write about signs from languages not connected to the written language used to talk about them. The content of this textbook is presented in written English, so we use English to write signs in ASL, but what should we do for a signed language like langue des signes québécoise (LSQ, Quebec Sign Language), which has no connection to English?

One option is to write the sign in English, so we could write about the ASL sign BED and the LSQ sign BED. Another option is to write the sign using the ambient written language most connected to that signed language, and add a gloss in English. In this case, LSQ has a connection to French, so we could write about the ASL sign BED but the LSQ sign LIT ‘bed’, using the French word lit. Both options have advantages and drawbacks, and you will see both used in the linguistics literature, though the first option is perhaps the most common.

For signed languages, we have two main categories of articulators to analyze the properties of. The manual articulators are the arms, hands, and fingers, which are the primary articulators used for signing (and the source of the articulatory half of the name of the signed language modality, manual-visual). However, most of the rest of the body is also used in signed languages, especially the torso, head, and facial features. All of these other articulators are called the nonmanual articulators or sometimes just nonmanuals.

Manual articulators

The manual articulators move by means of joints, which are points in the body where two or more bones come together to allow for some kind of movement. There are six joint types in the manual articulators: shoulder, elbow, radioulnar joint (or simply radioulnar), wrist, base knuckles, and interphalangeal joints (or simply interphalangeal), arranged as shown in Figure 3.20.

Skelton arms, with the shoulder, eblow, radioulnar, wrist, base knuckles, and interphalangeals labelled.
Figure 3.20. Joints in the manual articulators.

Shoulder articulation

The shoulder rotates inside the shoulder blade, allowing for a wide range of motion for the upper arm, as shown in Figure 3.21. The motion we use for jumping jacks, with the arms making up and down arcs out to the left and right of the torso is called abduction (for the upward/outward direction) and adduction (for the downward/inward direction). The motion for raising and lowering the arm up in front of us is extension (for raising) and flexion (for lowering). Finally, the shoulder can keep the upper arm in a fixed position while changing the position of the forearm through rotation. Movement at the shoulder joint can be any combination of these three kinds of movement.

Figure 3.21. Shoulder movement.

Elbow articulation

The elbow is the joint between the upper arm and forearm, and it has a more restricted range of motion than the shoulder, allowing only flexion (bending to bring the forearm closer to the upper arm) and extension (bending the opposite way), as shown in Figure 3.22. Other kinds of movements at the elbow are heavily restricted or impossible. Note that unlike the shoulder, the elbow cannot typically extend backwards from a hanging position, only from a flexed position.

Figure 3.22. Elbow movement.

Radioulnar articulation

The forearm contains two large bones, the radius (which is on the the thumb side of the arm) and the ulna (on the pinky side). The radius and ulna come together in three different places for three different kinds of movement: at the elbow, at the wrist, and in the middle of the forearm. All three of these points of movement are considered radioulnar joints biologically and have separate names (the superior radioulnar joint at the elbow, the inferior radioulnar joint at the wrist, and the medial radioulnar joint inside the forearm), but in the context of signed language phonetics, we normally only need to talk about one of them, since their movements are connected. By convention, the one we discuss is the medial radioulnar joint. At this radioulnar joint, the radius and ulna pivot around each other, allowing the forearm to rotate, as show in Figure 3.23.

Figure 3.23. Radioulnar movement.

Wrist articulation

The wrist is the joint between the forearm and the hand, and it is almost as mobile as the shoulder, as shown in Figure 3.24, allowing for abduction (sideways towards the thumb), adduction (sideways towards the pinky), extension (bending backwards), and flexion (bending forwards), but no rotation. Note that what we might initially think of as rotation at the wrist is actually due to radioulnar articulation. Like the shoulder, the wrist can typically extend backwards.

Figure 3.24. Wrist movement.

Base knuckle articulation

The base knuckles are the joints where the fingers meet the palm of the hands. Like the wrist, these joints allow for abduction, adduction, extension, and flexion, but no rotation, and like the elbow, the base knuckles cannot typically extend very far from a straightened position. The main movements available for the base knuckles are shown in Figure 3.25. Each base knuckle can generally move independently of the other, those some movements are more difficult than others.

Figure 3.25. Base knuckle movement.

Interphalangeal articulation

The interphalangeal joints are the various joints between the individual bones of the fingers. The thumb has only one interphalangeal joint, while the other four fingers have two interphalangeal joints each. Most humans cannot easily articulate the two interphalangeal joints of the same finger separately, so they are usually analyzed together for the purpose of signed languages. Like the elbow, the interphalangeal joints can only extend and flex, as shown in Figure 3.26, and they typically cannot extend much from a straightened position.

Figure 3.26. Interphalangeal movement.

Describing manual movement

An important aspect of describing manual movement in a sign is being able to identify which joints are moving and what kind of movement they are using to move. This can be quite difficult, because many signed language articulations use multiple joints moving in different ways. In the following discussion, we explore a few example signs from ASL to determine kind of movement is occurring.

First consider the ASL sign SORRY in the following video clip.

First, note that the hand must raise up to the chest before the sign begins. This movement does not really count as part of the sign. It is similar to how phones are articulated. In order to make an alveolar plosive like [t], the tongue tip must make full contact with the alveolar ridge. The movement to the alveolar ridge is not part of [t] itself, but a necessary bit of incidental movement to get ready to articulate [t]. We can tell that this movement is not part of [t] because of the behaviour or words like ant [ænt]. Since the tongue tip is already on the alveolar ridge for [n], we do not need to move it away and the move it back for [t]. The same is true for the positioning movement for the beginning of SORRY, as well as the final movement to return the hands in the lower position. We only care about the core movement that happens during the sign itself, not the transitional movement into or out of the sign. Sometimes, it may be difficult to determine whether a movement is an incidental transitional movement or not, but most of the time, it should be clear what initial and final movements can be ignored.

Now consider the articulation of the hand. It is shaped into a rigid fist, which requires flexing the base knuckles and the interphalangeal joints (except for the thumb, which is extended). However, this is a fixed configuration, not a movement, so we can ignore those joints. The actual movement is the hand tracing a small circle on the chest. There seems to be no significant movement at the wrist or radioulnar joints either, since the entire forearms down through the hand and fingers all act as a single fixed unit. Thus, we can also ignore these two joints as well.

That leaves the elbow and shoulder as our joints of interest for manual movement. Looking carefully at the elbow, we see that it flexes and extends slightly during the circle, causing a change in the angle between the upper arm and forearm. In addition, the elbow itself also changes position in space, moving a bit out to the signer’s right side and back again. This cannot be due to elbow movement, since joint movement cannot change the position of a joint itself, but rather, the position of the other body parts it is connected to. Thus, there must also be some other movement elsewhere, and the only joint we have left is the shoulder. The relevant shoulder movement appears to be a small amount of abduction and adduction, perhaps combined with very slight flexion and extension as well.

So, we would say that SORRY in ASL has elbow and shoulder movement, and if we need to be more precise, we would say that there is repeated flexion and extension of the elbow, and repeated abduction and adduction of the shoulder, and perhaps also some amount of repeated flexion and extension of the shoulder.

Next, consider the ASL sign APPLE in the following video clip.

Again, we must ignore the transitional movements into and out of the sign, and as with SORRY, we see that the hand in APPLE is in a fixed shape, this time with the index finger extended at the base knuckle but flexed at the interphalangeal joints, while all of the other fingers are closed loosely together with flexed base knuckles and interphalangeal joints.

For APPLE, there is movement of the forearm in the form of rotation. We know that the wrist cannot rotate, so this must be due to radioulnar rotation. There is no other movement, so we can ignore the elbow and shoulder joints.

Thus, for APPLE in ASL, we would say that it has radioulnar movement only, and more precisely, that it has repeated radioulnar rotation.

Finally, consider the ASL sign CHOOSE in the following video clip.

For CHOOSE, the initial transitional movement almost looks like it could be part of the sign, with the hand raising, then flicking backward, as all part of one motion. In this particular case, we can ignore this initial raising, but in general, and it can be difficult to know whether to ignore it or not.

The core movements that we are concerned with here are the movements of the fingers and the backward wrist flick. For the finger movement, we see that the index and thumb come together in a pinching motion. This requires flexion of the base knuckles, and perhaps a very small amount of interphalangeal flexion. The backwards wrist flick is articulated by extending the wrist backward. There is no radioulnar twisting and no notable elbow or shoulder movement.

Thus, for CHOOSE in ASL, we would say that it has base and radioulnar movement, and perhaps some minor interphalangeal movement, and more precisely, that it has non-repeated base (and maybe interphalangeal) flexion and wrist extension.

Nonmanual articulators

The rest of the body, the nonmanual articulators, especially the torso and the parts of the face, have complex and varied movement, such as eye gaze direction, eyelid aperture, eyebrow raising or lowering, torso leaning or rotation, head tilting or rotation, cheek puffing, lip rounding or spreading, teeth baring, etc. Nearly any other body part can be a nonmanual articulator, including the feet and buttocks in some signed languages, such as Adamorobe Sign Language in Ghana (Nyst 2007) and Kata Kolok in Indonesia (Marsaja 2008).

If you look back at the ASL sign SORRY, you should notice some of these nonmanual articulations. The signer furrows his brow, pushes his lips together, slightly puffs his cheeks, and gives a slow head shake. All of these nonmanual movements are part of the sign. For any given sign, the nonmanual articulations may not all be necessary to understand the sign, but they are still part of its articulation.

Nonmanual articulation is beyond the scope of an introductory textbook like this, but it plays a crucial role in signed languages and cannot be ignored in a full analysis of signed languages. This is one of the drawbacks for tools like “signed language gloves”, such as those that regularly pop up in popular media (a typical example is presented in Chin 2020). Since these gloves only capture some aspects of manual articulation, but no nonmanual articulation at all, they cannot fully translate signed languages. See Hill 2020 for further discussion of this issue, in particular, the need for creators to involve deaf people when designing signed language technology, to ensure that the technology is actually useful to deaf people.

Check your understanding

Coming soon!


Chin, Matthew. 2020. Wearable-tech glove translates sign language into speech in real time. UCLA Newsroom.

Hill, Joseph. 2020. Do deaf communities actually want sign language gloves? Nature Electronics 3(9): 512–513.

Marsaja, I. Gede. 2008. Desa Kolok — A deaf village and its sign language in Bali, Indonesia. Nijmegen: Ishara Press.

Nyst, Victoria. 2007. A descriptive analysis of Adamorobe Sign Language (Ghana). University of Amsterdam PhD dissertation.


Icon for the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License

Essentials of Linguistics, 2nd edition by Catherine Anderson; Bronwyn Bjorkman; Derek Denis; Julianne Doner; Margaret Grant; Nathan Sanders; and Ai Taniguchi is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

Share This Book