Dr. McLeod ve Dr. Crowe from Charles Sturt University in Australia published a cross linguistic review on acquisition of consonants in 2018 at American Journal of Speech-Language Pathology. The researchers reviewed in detail 60 articles that was published in between 1931 and 2016 on the acquisition of consonants in 27 languages, including Turkish.
The Importance of the Acquisition of Consonants
Children's ability to master at speech depends on their understanding and use of consonants, consonant clusters, vowels, prosodic features (intonation, stress) and phonological rules. Therefore, mastery at consonants is the most common measure to monitor both typical phonological development and phonological disorders.
As a result, it is very important to know how and in which order children acquire consonants in order to diagnose articulation disorders at early ages, since early diagnosis may lead to early intervention. In this way, children who got supported at earlier ages can catch up with their peers in terms of typical speech and language development in a shorter period of time.
Hypotheses on Acquisition of Consonants
In the literature, some researchers claims that acquisition of phonological structures such as consonants and vowels follows a universal order in all languages, while other researchers claim that individual differences determine the phonological development and have a tendency to oppose the idea of universal acquisition.
In recent years, some researchers indicated that it is important to pay attention to both universal acquisition principles and individual differences especially while working with bilingual/multilingual children.
In this study, the researchers reviewed 60 articles published on consonant acquisition in 27 languages, including Afrikaans, Arabic, Cantonese, Danish, Dutch, English, French, German, Greek, Haitian Creole, Hebrew, Hungarian, Icelandic, Italian, Jamaican Creole, Japanese, Korean, Malay, Maltese, Mandarin (Putonghua), Portuguese, Setswana (Tswana), Slovenian, Spanish, Swahili, Turkish, and Xhosa to investigate the age of acquisition of consonants, place (e.g., labial, alveolar) and manner (e.g., trill, fricative) of consonant production, and correct production rate of consonants by age cross-linguistically. Besides, the researchers indicated that they performed an inter-rater reliability check.
The main findings of this study showed that in all languages the children acquired 93% of the consonants by the age 5 and supported the principle of universal phonological development. The researchers indicated that in terms of the manner of consonant production, the children acquired plosives, nasals, and nonpulmonic consonants (e.g., clicks) earlier than trills, flaps, fricatives, and affricatives. In addition to that, liquids were not always precede fricatives. In terms of the place of consonant production, the children acquired labial, pharyngeal, and posterior lingual (palatal, velar, and uvular) consonants earlier than those using an anterior lingual placement (dental, alveolar, postalveolar, and retroflex). However, the consonants that the children failed to produce by age 5 differed among languages. Therefore, the researchers emphasized the impact of language specific features and individual differences.
In summary, the researchers stressed out that in all languages the children complete consonant acquisition by age 5, and warned speech and language pathologist to pay attention to the individual differences in the process of consonant acquisition.
The Contribution to Our Knowledge
Based on this study, we can refine our knowledge about the age and order of acquisition of phonemes which may help us to set realistic expectations for children. This is not only important for speech and language pathologists, but also important for parents as well.
If your child is younger than 5 years old and he is not able to produce certain phonemes, then you may prefer to focus on things that he can do and spend fun time with your child, rather than getting stressed just because he is not having the anatomical abilities to produce these phonemes yet.
Similarly, if your child is older than 5 years of age and he is not able to produce certain phonemes, you may consider getting an opinion of a speech and language pathologist instead of thinking that "He will catch up eventually".
In line with the findings of this study, we can prepare intervention and therapy programs for children with articulation problems which are sensitive to both universal principles and individual differences in acquisition of consonants at the same time.