The preschool years (approximately ages 3-5) are filled with rapid growth and development. Children are learning how to navigate their social and emotional world through play, while they continue to develop and hone their speech, language, and motor skills. This is an exciting time, and chances are your child wants to share their thoughts, feelings, and experiences with you!
So what happens if you can't understand what your child is trying to tell you? How do you know if the speech sound errors you're hearing are age-appropriate or a red flag?
Let's start by discussing speech intelligibility. Speech intelligibility is SLP jargon for "how well can others understand your child's speech". By the time a child is 3 years old, others should be able to easily understand 75%-100% of their verbal speech output. Parents often understand their children more easily (e.g. Billy's mother states she understands 90% of his speech) than adults who are less familiar with the child's speech sound production (e.g. Billy's new teacher states she understands 75% of his speech). By the time a child is 4, he or she should be 100% intelligible to all conversational partners, including strangers.
With that being said, typical speech sound development research has shown that speech sounds don't all develop at once. Some sounds develop earlier while others are later to the game. For example, sounds such as "r" and "th" may not be mastered until after 5 years old. Click here to see a more detailed consonant acquisition chart.
While children are still developing their speech sounds, they often adopt ways of simplifying words by using "rules" or patterns in order to help them say difficult words more easily. These patterns are known as phonological processes. The use of phonological processes is a typical part of speech sound development. Check out this great chart from Caroline Bowen (2011), that provides examples of commonly occurring phonological processes.
There are several error patterns, however, that are not typical and instead should be seen as red flags:
backing (e.g. "go" for "do", "key" for "tea") This is when a sound that is normally produced toward the front of the mouth is replaced by a velar sound such as /k/ or /g/.
initial consonant deletion ( e.g. "at" for "cat")
glottal stopping/substitution (e.g. "ta-ing" for "talking") This is when a consonant is replaced by a glottal stop sound.
vowel errors ("kay" for "key")
If you notice your child demonstrates any of the phonological processes above, reach out to a speech-language pathologist for a consultation.
Ok, but when should the "normal" error patterns go away? Even in typical speech sound development, phonological processes should eventually be eliminated; often during those preschool years. The following phonological processes should be eliminated by age 3:
pre-vocalic voicing ("bat" for "pat"), where a voiceless sound (e.g. /p/) is changed to a voiced sound.
word-final de-voicing ("dug" for "duck") where the word final "voiced" sound (e.g. /g/) is changed to a voiceless sound (e.g. /k/)
stopping of /s/ and /f/ ("doe" for "so" or "tish" for "fish")
By age 3;6, the following phonological processes should be eliminated:
fronting ("tea" for "key"), where a sound made in the back of the throat (e.g. /k/) is replaced by a sound made in the front of the mouth (e.g. /t/).
stopping of /v/ and /z/ ("ban" for "van" or "dip" for "zip")
By age 4, the following phonological processes should be eliminated:
cluster reduction ("nake" for "snake", "pin" for "spin, or "keen" for "clean")
weak syllable deletion ("nana" for "banana" or "mato" for "tomato"
consonant harmony ("mime" for "mine")
I often get questions from parents regarding the substitution of /w/ or "y" for /l/ (e.g. "wion" for "lion". This phonological process is known as gliding and should be eliminated by around 5 years of age. Additionally, stopping of "th" ("dey" for "they") is also typically gone around 5 years of age.
If you suspect your child's speech sound errors are not typical for their age, contact a speech-language pathologist. Even if you are able to decipher your child's speech, but others are reporting difficulty understanding your child, it may be worth getting an SLP's opinion. Phonology is not only crucial in speech, but also in literacy. If you think something may be wrong, don't let your child fall behind.
Thanks for reading! :)
Bowen, C. (2011). Table 3: Elimination of Phonological Processes. Retrieved from http://www.speech-language-therapy.com/ on [ 07/31/2018].
Bowen, C. (2011). Table1: Intelligibility. Retrieved from http://www.speech-language-therapy.com/ on [07/31/2018].