Speech sound disorders is an umbrella term used to refer to any difficulty, or combination of difficulties, with how speech sounds are perceived, produced or represented in the brain. There are several major types of speech sound delays/disorders that are listed below.
Articulation is the ability to move lips, tongue, palate, and jaw to produce speech sounds called phonemes.
An articulation disorder is characterized by difficulty producing individual speech sounds. If your child has an articulation disorder, they may have problems making sounds and forming particular speech sounds properly. For example, a child may have difficulty with the /l/ sound and may say "wamp" for "lamp."
When children are young, articulation errors are common. Just like the rest of their body, their mouths and brains have to develop and learn how to work together, which is a learning process, just like learning to walk. However, sometimes articulation errors may persist past the time when they are developmentally appropriate; when this happens, the errors are considered to be an articulation disorder.
Typical ages of sound acquisition for English speaking children (keep in mind that all kids are different, and so the development of speech sounds, especially later development sounds, may vary slightly between children):
Age 2-3: /p,b,m,n,t,d,w,h/ & vowels
Age 4: /f,k,g,y/
Age 5: /ch,dg,l,sh,s,ng/
Age 6: /v,z/
Age 7+: /r,th/
Phonology refers to the pattern in which sounds are put together to make words.
Phonological processes are the patterns young kids use to simplify speech. It is typical for many children to use these patterns while their speech and language skills are developing (around the age of 3). As children mature, so does their speech, and they stop using these patterns. However, when the patterns persist past when it is developmentally appropriate, it is called a phonological disorder.
Some common phonological processes that can occur are:
Cluster reduction: when some or all of the sounds of the consonant cluster are omitted (e.g. "top" for "stop").
Syllable Deletion: when an unstressed syllable is omitted from a word (e.g. "nana" for "banana").
Fronting: when a sound that is meant to be produced in the back of the mouth, such as /g/, is replaced with a front sound such as /t/ (e.g. "tat" for "cat")
Stopping: when a fricative (one that requires air to be forced out of the mouth such as /s, z, f/) is changed to a stop sound such as /t, d, b/ (e.g. "tun" for "sun").
Gliding: substituting /w/ for /l/ or /r/ (e.g. "wabbit" for "rabbit").
It can be much more difficult to understand children with phonological disorders than children with pure articulation disorders. Children with phonological disorders often have problems with many different sounds, not just one.
Childhood Apraxia of Speech
Childhood Apraxia of Speech, also known as CAS, is a motor speech disorder that makes it difficult for a child to learn to talk.
Concerns about CAS typically arise when a toddler's first spoken words are not developing as expected. Children with CAS have great difficulty planning and producing precise, highly refined and specific series of movements of the tongue, lips, jaw and palate that are necessary for intelligible speech (this is why CAS is referred to as a motor planning disorder).
Generally, CAS children have a good understanding of language and know what they want to say but have significant difficulty using spoken language. Therapy for CAS is based on the principles of motor learning which is necessary for children with apraxia to make progress. I have additional training through PROMPT and Nuffield (NDP3) that allows me to provide appropriate and beneficial treatment for children with this disorder.
A 'lisp" is a term often used to describe difficulty making clear, easy to understand /s/ and /z/ sounds. This may or may not also include the tongue sticking out of the mouth. A lisp most likely has a phonetic origin, meaning a child has difficulty physically achieving the correct placement of their lips, tongue and/or jaw. This results in errors when saying clear, easy to understand speech sounds. Lisps are a common type of 'functional" speech disorder (FSD), meaning that the cause of the disorder is unknown.
There are four types of lisps:
Interdental Lisp - this is the most common type. It occurs when the child tries to say s/z sounds with the tongue sticking out between the teeth, resulting in the 'th' sound.
Lateral Lisp - occurs when the air is directed over the sides of the tongue instead of down the middle. For this reason, air flows over the tip of the tongue on the s/z sounds, resulting in the sounds sounding "slushy." A lateral lisp is not an expected error in typically developing speech, so it requires therapy.
Palatal Lisp - this is a less common lip and occurs when a child tries to say s/z sounds with the tongue touching the soft palate (the roof of the mouth).
Dentalised Lisp - when the child pushes the tip of their tongue up against their front teeth, resulting in a "muffled" s/z sound.
Interdental and dentalised lisps are considered part of typical child speech development; however, if the child has lateral or palatal lisp & they are 4 years of age or older, it is recommended that they receive speech therapy.