Structure Matters: Looking Beyond What We Hear in Speech

When we evaluate a child’s speech, we spend a lot of time listening. What sounds are correct? What sounds are distorted? Are there substitutions, omissions, or patterns?

But speech isn’t produced by a transcription. Speech is movement—and movement happens within a physical system.

The jaw, lips, tongue, palate, dentition, and surrounding oral structures create the physical environment in which speech occurs. That does not mean every structural difference causes a speech sound disorder. It does mean that structure deserves our attention when we are trying to understand how a child is producing speech.

I like to think of the oral cavity as the workspace for speech. The tongue has to move within the space created by the palate, dentition, alveolar ridge, and mandible. The lips interact with the teeth and jaw. The jaw provides an important biomechanical foundation from which increasingly refined and differentiated movements of the lips and tongue can emerge.

This is why structure and biomechanics cannot be completely separated from movement.

If I observe a high or narrow palate, an occlusal difference, or another structural variation, I don’t want to immediately conclude, “That is causing the speech error.”

Instead, I want to know what happens during speech.

How is the tongue interacting with the available space? Can the child establish and maintain the required tongue shape? Is the jaw stable? Can the lips and tongue move with sufficient independence from the jaw? Are compensatory movements emerging?

Structure should make us curious, not certain.

This is particularly important when we consider speech motor development. Namasivayam et al. (2025) examined speech motor control in children with moderate-to-severe speech sound disorders, including jaw opening and grading, midline jaw control, labial-facial control, jaw-lip integration, and tongue movements independent from the jaw. Their findings demonstrated associations between limitations in speech motor control and several error patterns traditionally characterized through their perceptual or phonological output.

This does not mean that every speech error is motor-based. It means that what we hear may reflect limitations occurring elsewhere within the speech production system.

And sometimes the most valuable information is found in the child’s compensations.

If the jaw shifts during a lingual target, what problem is that movement solving? If the tongue moves with the jaw, is the child using the jaw to create additional stability? If a sound is accurate in isolation but deteriorates as syllable complexity or rate increases, what does that tell us about the stability of the movement?

Instead of immediately trying to eliminate a compensation, I want to understand why the speech system is using it.

This connects directly with our 2025 paper, Reevaluating the Classification of Pediatric Speech Sound Disorders: A Ground Truthing Perspective. Namasivayam and colleagues challenge us to recognize the limitations of relying exclusively on auditory-perceptual classifications. What we hear is incredibly important, but it does not always reveal everything happening at the movement level. Instrumental research has demonstrated subtle motor behaviors—including covert contrasts and undifferentiated tongue gestures—that may not be apparent through listening alone.

So we cannot simply listen to speech and assume the mechanism. And we cannot simply look at structure and assume function.

We have to connect the two.

During your next speech evaluation, don’t stop at “What did I hear?”

Look at the structure available for speech. Observe the jaw, lips, and tongue during the actual speech task. Look for compensations. Change the vowel, rate, syllable structure, or complexity and see what happens.

Most importantly, ask:

Is what I observed structurally actually affecting speech function?

Because structure alone isn’t the diagnosis.

And understanding the relationship between structure, movement, and function can move us toward more individualized and precise speech assessment and intervention.

References

Namasivayam, A. K., Li-Han, L. Y., Moore, J. G., Wong, W., & van Lieshout, P. (2025). The articulatory basis of phonological error patterns in childhood speech sound disorders. Frontiers in Human Neuroscience, 19, 1635096.

Namasivayam, A. K., et al. (2025). Reevaluating the classification of pediatric speech sound disorders: A ground truthing perspective. Frontiers in Human Neuroscience, 19, 1700505.