“Clear speech is characterized by symmetrical jaw movement and dissociated lip and jaw movement.” — Linda D’Onofrio
When we think about speech development and clarity, much of the focus is placed on the tongue — particularly in relation to place, manner, and voicing. While this is an important part of speech production, it can sometimes lead us to overlook something more foundational: the role of the jaw and the importance of coordinated and independent oral movements.
Clear speech doesn’t begin with individual sounds. It begins with jaw stability.
Why Jaw Stability Matters
For speech to develop efficiently, the jaw needs to move in a stable and symmetrical way. This stability provides the foundation for the lips and tongue to perform precise, refined movements.
A helpful way to visualise this is to think of a human pyramid. The base must be strong and steady to support everything above it. In the same way, the jaw provides the base for speech.
When the jaw is stable:
- The lips can move with greater precision
- The tongue can achieve the speed and accuracy needed for clear speech
- Movements are more efficient and less effortful
However, when the jaw moves excessively or unevenly, other structures often compensate. This can lead to:
- Reduced speech clarity
- Distorted sounds
- Increased effort when speaking
- Fatigue in the oral muscles
Understanding Dissociation
Dissociation refers to the ability of the jaw, lips, and tongue to move independently of one another.
In early development, babies use more associatedmovements. During babbling (e.g. “da da”), the jaw drives the movement, and the tongue follows. This is a normal and important stage.
As children develop, they learn to separate these movements. For example, instead of the jaw moving up and down to produce a /d/ sound, the jaw can remain stable while the tongue tip independently elevates to the alveolar ridge. This allows for greater precision and clarity.
When dissociation does not develop effectively, speech can become less efficient and less accurate, as the tongue and jaw continue to move 
together rather than independently.
Building the Foundation: Rest Posture and Chewing
Before we can expect refined, dissociated movements, we need to establish the foundations — particularly jaw stability. Two key elements that support jaw stability are tongue resting posture and chewing.
Centralised Tongue Resting Posture
The optimal resting position is with the tongue gently suctioned against the palate, evenly. In this position:
- The lateral margins of the tongue rest against the inside of the molars
- The jaw is held in a higher, more stable position
When this resting posture is established, it naturally supports jaw stability.
However, some children may not achieve this position. This can occur if they:
- Are mouth breathers
- Have a restricted lingual frenulum
- Have a very narrow palate
In these cases, the tongue may rest on the floor of the mouth. When this happens, the jaw often lowers, the muscles become less active and stability is reduced
Supporting a centralised tongue resting posture is a key step in building the foundation for clear speech.
The Role of Chewing
Chewing is another powerful way to develop jaw stability — particularly bilateral chewing.
If a child consistently chews on one side, the muscles on that side become stronger, leading to imbalance. Over time, this can affect the symmetry and stability of jaw movement.
By teaching children to chew on both sides:
- Muscle strength develops more evenly
- Jaw movement becomes more symmetrical
- A more stable base for speech is created
Looking Beyond Speech Sounds
When we support these foundational elements early, we are not just improving speech clarity in the moment. We are helping children develop efficient motor patterns that form a strong foundation for precise and rapid tongue placement.
Sometimes, the key to clearer speech isn’t asking a child to repeat a sound over and over again. Sometimes, the real work begins with something much more fundamental:
- Where the tongue rests
- How the jaw moves
As outcome-driven clinicians, we should look beyond individual sounds to understand how oral function influences articulation. By strengthening these underlying patterns, we can support more effective, efficient, and sustainable speech development.
