also be heard as a fricative []. Sounds [, ] are from Spanish loanwords. Grammar Verb morphology In Chiquihutlán Mazatec, verb stems are of the shape CV (consonant+vowel) and are always inflected with a stem-forming prefix marking person and number of the subject and aspect. In addition, verbs always carry a suffix that marks the person and number of the subject. The vowel of the suffix fuses with the vowel of the verb stem. There are 18 verb classes distinguished by the shape of their stem-forming prefixes. Classes 1, 2, 7, 10 and 15 cover intransitive verbs, and the rest of the classes involve transitive verbs. Transitive verbs have two prefix forms, one used for third person and first person singular and another used for the other persons (2nd person plural and singular and first person plural inclusive and exclusive). Clusivity distinctions as well as the distinction between second and first person is marked by the tonal pattern across the word (morphemes and stem do not have inherent lexical tone). Person Chiquihuitlán Mazatec distinguishes between three person categories (first, second, and third) and two numbers (singular, plural), and for the first person plural, it distinguishes between inclusive and exclusive categories. In the third person, number is not specified but only definiteness (definite or indefinite). Number is not expressed by free pronouns or noun phrases if it is directly retrievable from context. Tense and aspect Chiquihuitlán Mazatec inflects for four aspects: completive, continuative, incompletive, as well as a neutral or unmarked aspect. Completive aspect is formed by prefixing /ka-/ to the neutral verb form, continuative is formed by prefixing /ti-/. The incompletive aspect has a distinct set of stem forming prefixes as well as distinct tone patterns. In incompletive transitive verbs, only the first-person singular and the third-person prefixes vary from the corresponding neutral forms; the first-person plural and the second-person forms are identical to the corresponding neutral forms. Whistle speech Most Mazatec communities employ forms of whistle speech in which linguistic utterances are produced by whistling the tonal contours of words and phrases. Mazatec languages lend themselves very well to becoming whistling languages because of the high functional load of tone in Mazatec grammar and semantics. Whistling is extremely common for young men, who often have complex conversations entirely through whistling. Women, on the other hand, do not generally use whistle speech, just as older males use it more rarely