Speech therapy often works by breaking down complex communication goals into smaller, manageable steps to ensure consistent progress. For individuals learning to produce specific speech sounds, the task requires precise coordination of the tongue, jaw, lips, and breath. Since expecting a perfect sound immediately can be overwhelming, therapists use a structured method to guide the client toward the correct motor action. The concept of “approximation” is a fundamental tool in this process, allowing clients to build confidence and muscle memory gradually as they learn.
Defining Approximation in Speech Therapy
An approximation is a sound or movement that is close to the target sound but not yet produced with complete accuracy. It serves as an intermediate step that the speech-language pathologist accepts and reinforces because it represents forward movement toward the ultimate goal. The approximation is generally a sound that is relatively easy to elicit. It is similar to the target sound, perhaps sharing a common place of articulation or manner of production. By reinforcing these partially correct attempts, the therapist maintains motivation and establishes a pattern of successful communication.
The Systematic Approach to Achieving Target Sounds
The methodology that relies on approximations is formally known as “shaping” or “successive approximation.” This systematic approach is rooted in behavioral science and involves a step-by-step process of modifying behavior toward a desired outcome. The process begins with the therapist identifying the client’s current sound repertoire and establishing a clear target sound.
The therapist identifies the first successful approximation, which is the sound or motor movement closest to the target that the client can consistently make. This initial attempt is immediately reinforced. Reinforcement is a powerful mechanism that encourages the client to repeat the desired behavior.
Once the client masters the first approximation, the criteria for reinforcement are gradually increased. The therapist requires the client to make a slight modification, demanding a sound that is progressively closer to the final target sound. This may involve subtle changes in tongue position, airflow, or vocal cord vibration.
The therapist continues to raise the bar in small increments, reinforcing only the attempts that represent an improvement over the last successful approximation. This meticulous process ensures that the client is always working within their zone of proximal development, guaranteeing success at each new, slightly more difficult step. Through this systematic progression, the client is eventually guided to the accurate and complete production of the target sound.
Practical Examples of Approximating Sounds
A common application of shaping is helping a client achieve the correct /s/ sound, especially when they exhibit a lateral lisp. Another frequent example is moving from the /l/ sound to the more complex /r/ sound.
Approximating the /s/ Sound
Since the alveolar place of articulation is similar for both the /t/ and /s/ sounds, the therapist may use the client’s ability to produce a /t/ as a starting point. The client is instructed to produce the /t/ sound, which involves elevating the tongue tip to the alveolar ridge, and then to release the air with a strong burst while slowly retracting the tongue. This controlled modification of the /t/ sound can facilitate the turbulent, continuous airflow required for a correct /s/ sound. Once a sound that is a close approximation of the /s/ is produced, the therapist refines the tongue and jaw placement through auditory and visual cues.
Approximating the /r/ Sound
To approximate the /r/ sound, the therapist might instruct the client to start with the /l/ sound, where the tongue tip touches the alveolar ridge just behind the front teeth. The client is then guided to slowly drag the tongue backward along the roof of the mouth, transitioning from the hard palate to the soft palate. This movement encourages the back of the tongue to bunch up, which is a required motor action for the /r/ sound. The therapist reinforces the client’s ability to produce the initial /l/ sound with a slight retraction, which is a closer approximation to the target sound.