<P> There has been a trend to reduce and simplify consonant clusters in East Asian languages, such as Chinese and Vietnamese . Old Chinese was known to contain additional medials such as / r / and / or / l /, which yielded retroflexion in Middle Chinese and today's Mandarin Chinese . The word 江, read as jiang in Mandarin and kong in Cantonese, was most likely klong or krung . Additionally, initial clusters such as "tk" and "sn" were analysed in recent reconstructions of Old Chinese, and some were developed as palatalised sibilants . Another element of consonant clusters in Old Chinese were analysed in coda and post-coda position . Some "departing tone" syllables have cognates in the "entering tone" syllables, which feature a - p, - t, - k in Middle Chinese and Southern Chinese varieties . The departing tone was analysed to feature a post-coda sibilant, "s". Clusters of - ps, - ts, - ks, were then formed at the end of syllables . These clusters eventually collapsed into "- ts" or "- s", before disappearing altogether, leaving elements of diphthongisation in more modern varieties . Old Vietnamese also had a rich inventory of initial clusters, but these were slowly merged with plain initials during Middle Vietnamese, and some have developed into the palatal nasal . </P> <P> Consonant clusters occurring in loanwords do not necessarily follow the cluster limits set by the borrowing language's phonotactics . These limits are called restraints or constraints (see also optimality theory). A loanword from Adyghe in the extinct Ubykh language, psta (' to well up'), violates Ubykh's limit of two initial consonants . Also, the English words sphere / ˈsfɪər / and sphinx / ˈsfɪŋks /, Greek loanwords, violate the rule that two fricatives may not appear adjacently word - initially . </P> <P> In English, the longest possible initial cluster is three consonants, as in split / ˈsplɪt /, strudel / ˈʃtruːdəl /, and "squirrel" / ˈskwɪrəl /, all beginning with / s / or / ʃ / and ending with / l /, / r /, or / w /; the longest possible final cluster is five consonants, as in angsts in some dialects / ˈæŋksts /, though that is rare (perhaps owing to the fact that it is a derivative of a recent German loanword), while final clusters of four consonants, as in sixths / ˈsɪksθs /, twelfths / ˈtwɛlfθs /, bursts / ˈbɜːrsts / (in rhotic accents) and glimpsed / ˈɡlɪmpst /, are more common . Within compound words, clusters of five consonants or more are possible (if cross-syllabic clusters are accepted), as in handspring / ˈhændspriŋ / and in the Yorkshire place - name of Hampsthwaite / hæmpsθweɪt / . </P> <P> It is important to distinguish clusters and digraphs . Clusters are made of two or more consonant sounds, while a digraph is a group of two consonant letters standing for a single sound . For example, in the word ship, the two letters of the digraph ⟨ sh ⟩ together represent the single consonant (ʃ). Conversely, the letter ⟨ x ⟩ can produce the consonant clusters / ks / (annex), / gz / (exist), / kʃ / (sexual), or / gʒ / (some pronunciations of "luxury"). It is worth noting that ⟨ x ⟩ often produces sounds in two different syllables (following the general principle of saturating the subsequent syllable before assigning sounds to the preceding syllable). Also note a combination digraph and cluster as seen in length with two digraphs ⟨ ng ⟩, ⟨ th ⟩ representing a cluster of two consonants: / ŋθ / (although it may be pronounced / ŋkθ / instead, as ⟨ ng ⟩ followed by a voiceless consonant in the same syllable often does); lights with a silent digraph ⟨ gh ⟩ followed by a cluster ⟨ t ⟩, ⟨ s ⟩: / ts /; and compound words such as sightscreen / ˈsaɪtskriːn / or catchphrase / ˈkætʃfreɪz / . </P>

Using phonetic transcription identify only the consonant cluster in the word polytechnic