Speech therapy unvoiced th: The unvoiced /θ/ is a fricative stream of air sound. The tongue tip has gentle contact with the upper front teeth which creates a narrow channel and confined space for the air-stream to flow through.
The compression of this narrow space creates a friction as the unvoiced air-stream flows through the slightly restricted area. The jaw is lowered marginally to provide for the correct tongue positioning.
A common sound substitution for the /θ/ is the unvoiced fricative /f/. So thorn becomes forn. The /θ/ sound is a later developing sound. Many children with normal speech and language development don’t produce a correct /θ/ sound until 7-8 years of age and so should not be considered a sound error for children under 5-6 years of age.
Speech Sound Structures - /θ/ Sound
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/θ/ Sound Stimulation
Work through the following procedures with your child.
Many speech sounds can be sculpted using other speech sounds as a starting point. This involves altering or adjusting speech sounds so that they approach the target sound in nature. This works by the clinician modeling a sound that the child is able to produce. The clinician then makes slight, progressive adjustments to the sound until the target sound is generated.
Sound sculpting from the /t/ sound
Instruct your child to initially hold tongue position for the /t/ sound. The child then slowly and progressively moves the tongue forward under the top teeth while maintaining the air-stream.
Sound sculpting from the /f/ sound
Instruct your child to produce the /f/ sound while being conscious where the tongue is positioned during /f/ production (it should be just behind the teeth not touching any structures). The child then slowly and progressively moves the tongue forward to essentially rupture the /f/ sound. The tongue should be poking through the front teeth, which redirects the air-stream and produces a clear /θ/ sound.