Why are English words with several consonants in a row difficult for some language learners to pronounce?

English words containing several consonants in a row, known as consonant clusters, can be challenging for language learners because they require precise, rapid adjustments in the vocal tract. In the formation of consonants, the airstream is obstructed at specific places of articulation, such as the lips, teeth, or various parts of the tongue and palate.1

When multiple consonants appear together, a speaker must navigate these obstructions in quick succession. Language change often trends toward "ease of pronunciation," where speakers naturally favor patterns that require the least physical effort. Because learners are accustomed to the phonological rules and syllable structures of their native languages—which may not permit such complex clusters—they may find it difficult to execute the necessary motor movements for English sequences. While some languages, such as certain Indigenous North American languages, utilize even more complex clusters, learners of English often struggle because these sequences do not align with the rhythmic or structural habits of their first language.234