A simplified form of Motu developed as a trade language in the Papuan region, in the southeast of the main island of New Guinea, originally known as Police Motu, and today known as Hiri Motu. After Tok Pisin and English, Hiri Motu was at the time of independence the third most commonly spoken of the more than 800 languages of Papua New Guinea, although its use has been declining for some years, mainly in favour of Tok Pisin.
Motu is a typical Austronesian language in that it is heavily vowel-based. Every Motu syllable ends in a vowel sound — this may be preceded by a single consonant (there are no "consonant clusters"). Vowel sounds may be either monophthongs (consisting of a single basic sound) or diphthongs (consisting of more than one basic sound).
There are only five vowel sounds /a,e,i,o,u/;[2] Motu diphthongs are written and pronounced as combinations of two vowels. The sounds oi and oe, ai and ae, au and ao (approximately like English boy, high, cow), and r and l are distinguished in Motu but not in Hiri Motu.[3] There is no letter f; when it occurs in loan words, it is usually represented as p.
^Unesco reports the language as simply "Motu", but Ethnologue 17 only notes braille usage for Hiri Motu. However, Hiri Motu does not have the letter ḡ.