Speech Sound Acquisition

As children are learning to speak, it’s perfectly natural for them to make mistakes along the way. One component of a speech-language pathologist’s job is deciding if a child’s errors are developmental or not. Developmental errors are considered to be age appropriate and do not require speech therapy. Non-developmental errors occur when a child continues to make an error past a certain age, or when they make an error that is not appropriate at any age.

Speech-language pathologists (SLPs) make these decisions with the help of speech sound acquisition norms. These norms provide a guideline for when children should start correctly producing each sound. Unfortunately, not all norms are the same. Different bodies of research advocate for different sounds emerging at different ages. A quick Google search will bring up dozens of different charts!

The American-Speech-Language-Hearing Association (ASHA), the governing body for SLPs, supplies this acquisition chart as a resource for parents and speech-language pathologists:

The above chart shows the average age of acquisition for each sound (where the bar starts), as well as the age at which 90% of all children have mastered the sound (where the bar ends). So, the average child masters the “t” sound at age two, and 90% of children produce it correctly by age six. If this seems like a big range to you, you’re not alone. Aside from the confusion of which acquisition norms to follow, parents may still not know if their child’s sound production is appropriate. Should they start therapy if their child is not making the “t” at two? At six? Somewhere in between?

This is where speech-language pathologists come in. They use their training and expertise along with sound acquisition norms to decide if errors are developmental or if therapy is required. Further, SLPs use their clinical judgement to determine if it’s appropriate to teach a sound that does not follow the typical developmental hierarchy. There are certain cases in which in might make sense to do so. For example:

1. If the child is stimulable for a sound. “Stimulability” refers to a person’s ability to imitate a sound in isolation, with or without cues. A child may be stimulable for a later developing sound rather than an earlier developing sound. In this case, teaching the later sound may make more sense, because the child will learn the sound faster and increase their intelligibility sooner.
2. If the child has mastered a similar sound. 90% of children master “f” by age four and “v” by age eight. The “f” and “v” sounds are considered to be “cognate pairs”. This means that they are produced the same way and in the same place in the mouth, and only differ by their voicing (“f” is voiceless and “v” is voiced). If a child has already mastered “f”, it is generally fairly easy to shape their current production into a “v”.
3. If a certain error sound is a high frequency sound. The voiced and voiceless “th” sounds are among the last sounds to develop. However, they are high frequency sounds, or sounds that occur often in our speech. If a child is missing several sounds and is highly unintelligible, it may be a good idea to teach “th” sounds. They are also some of the easiest sounds to teach, due to their visibility on the face (children can see your tongue between your teeth when you model the sound, unlike a sound such as “g” which is produced with the back of the tongue). So, the child will be able to learn these sounds quickly, and increase their intelligibility while working on their remaining sounds in error.

Most importantly, when assessing a child’s speech sound production, it is crucial to take their overall communication ability into account. Can they be understood by their peers, teachers, and extended family members? Are they feeling self-conscious about their errors, or are they experiencing social repercussions? Are the sound errors mirrored in their reading and writing skills and negatively impacting academics?

If you have any concerns regarding your child’s speech sound production, contact The Speech Studio. A licensed and certified speech-language pathologist can recommend the best course of therapy for your child’s individual needs. For more information, visit our website.