Mayan phonology

Proto-Mayan sound system
Proto-Mayan (the common ancestor of the Mayan languages as reconstructed using the comparative method) has a predominant CVC syllable structure, only allowing consonant clusters across syllable boundaries. Most Proto-Mayan roots were monosyllabic except for a few disyllabic nominal roots. Due to subsequent vowel loss many Mayan languages now show complex consonant clusters at both ends of syllables. Following the reconstruction of Lyle Campbell and Terrence Kaufman, the Proto-Mayan language had the following sounds; the sounds present in the modern languages are largely similar to this root set.

Phonological evolution of Proto-Mayan
The classification of Mayan languages is based on changes shared between groups of languages. For example, languages of the western group (such as Huastecan, Yucatecan and Ch'olan) all changed the Proto-Mayan phoneme into, some languages of the eastern branch retained  (K'ichean), and others changed it into  or, word-finally,  (Mamean). The shared innovations between Huastecan, Yucatecan and Ch'olan show that they separated from the other Mayan languages before the changes found in other branches had taken place.

The palatalized plosives and  are not found in any of the modern families. Instead they are reflected differently in different branches, allowing a reconstruction of these phonemes as palatalized plosives. In the eastern branch (Chujean-Q'anjobalan and Ch'olan) they are reflected as and. In Mamean they are reflected as and  and in Quichean as  and. Yucatec stands out from other western languages in that its palatalized plosives are sometimes changed into and sometimes.

The Proto-Mayan velar nasal is reflected as  in the eastern branches (Quichean–Mamean),  in Q'anjobalan, Ch'olan and Yucatecan, [h] in Huastecan, and only conserved as  in Chuj and Jakaltek.

Other innovations
The subgrouping of the Mayan family is based on shared linguistic innovations. Some phonological developments that have been used to establish the current classification are described here.

The divergent status of Huastecan is revealed by a number of innovations not shared by other groups. Huastecan is the only branch to have changed Proto-Mayan into. Wastek (but not Chicomuceltec) is also the only Mayan language to have a phonemic labialized velar phoneme. However, this is known to be a postcolonial development: comparing colonial documents in Wastek to modern Wastek, it can be seen that instances of modern were originally sequences of  followed by a rounded vowel and a glide. For example, the word for "vulture", which in modern Wastek is pronounced, was written $⟨cuyx⟩$ in colonial Wastek, and pronounced.

The grouping together of the Ch'olan and Yucatecan branches is partly based on the innovative change of short to. All Cholan languages have changed the Proto-Mayan long vowels and  to  and  respectively. The independent status of Yucatecan is evident in that all Yucatecan languages shifted proto-Mayan to  in word-final position.

Quichean–Mamean, and some Q'anjobalan languages, have retained Proto-Mayan uvular stops ( and ); in all other branches these sounds merged with and, respectively. Thus the Quichean–Mamean grouping can be said to rest mostly on shared retentions rather than innovations.

Mamean is largely differentiated from K'ichean by a chain shift which changed into,  into ,  into  and  into. These retroflex affricates and fricatives later spread to Q'anjob'alan through language contact.

Within the Quichean branch, Kaqchikel and Tz'utujil differ from Quichean proper in having changed a final Proto-Mayan and  into  and  respectively in polysyllabic words.

Some other changes are general throughout the Mayan family. For example, the Proto-Mayan glottal fricative, which no language has retained as such, has numerous reflexes in the various daughter languages depending on its position within a word. In some cases it lengthened a preceding vowel in languages which retained vowel length. In other languages it became, , , , or disappeared.

Other sporadic innovations have occurred independently in several branches. For example, distinctive vowel length has been lost in Q'anjobalan–Chujean (except for Mocho' and Akateko), Kaqchikel and Ch'olan. Other languages have transformed the length distinction into one of tense versus lax vowels, later losing the distinction in a majority of cases. However, Kaqchikel has preserved a centralized lax, schwa-like vowel as a reflex of Proto-Mayan. Two languages, Yucatec and Uspantek, as well as one dialect of Tzotzil, have introduced a tonal distinction in vowels, with high and low tones corresponding to former vowel length as well as reflecting and.