except a semivowel or a laryngeal consonant, as a low central vowel (for which IPA lacks a symbol) at the end of an open syllable or when followed by a laryngeal consonant, and as before a semivowel. In general, the long vowels do not feature this kind of variation but are simply lengthened versions of the phonemes that are represented in the chart. Caddo also has four diphthongs, which can be written a number of different ways; the transcription below shows the typical Caddo Nation orthography (a vowel paired with a glide) and the IPA version, represented with vowels and offglides. ay – English eye aw – English out iw – English ew uy – English boy Tone Caddo has three lexical tones: a low tone (e.g. /ù/), unmarked in the orthography ⟨u⟩; a high tone (e.g. /ú/), marked by an acute accent over the vowel ⟨ú⟩; and falling tone, which always occurs on long vowels (e.g. /ûː/) and is marked by a grave accent over the vowel ⟨ù꞉⟩. Tone occurs both lexically (as a property of the word), non-lexically (as a result of tonological processes), and also as a marker of certain morphological features. For instance, the past tense marker is associated with high tone. Tonological processes There are three processes that can create non-lexical high tone within a syllable nucleus. See the section below for an explanation of other phonological changes which may occur in the following examples. H-deletion VhCC → VHighCC An /h/ before two consonants is deleted and the preceding vowel gains high tone: /kiʃwɑhn-t-ʔuh/ → [kiʃwɑ́nːt'uh] "parched corn" Low tone-deletion VRVLowC → VHighRC A low tone vowel following a resonant (sonorant consonant) is deleted, and the preceding vowel gains a high tone. /sa-baka-nah-hah/ → [sawkɑ́nːhah] "does he mean it?" Backwards assimilation VRVHigh → VHighRVHigh A vowel preceding a resonant and a high tone vowel gains high tone. /nanɑ́/ → [nɑ́nɑ́ː] "that, that one"Phonological processes Vowel syncope There are two vowel syncope processes in Caddo, which both involve the loss of a low-tone vowel in certain environments. The first syncope process was described above as low tone-deletion. The second syncope process is described below:Interconsonantal syncopeVCVLowCV → VCCVA low-tone vowel in between a vowel-consonant sequence and a consonant-vowel sequence is deleted.(Shown with intermediary form): /kak#(ʔi)t'us-jaʔah/ → kahʔit'uʃaʔah → [kahʔit'uʃʔah] "foam, suds"Consonant cluster simplification As a result of the syncope processes described above, several consonant clusters emerge that