a. Metatheis applies when labial sonorants would otherwise occur before /r/ as the result of concatenation of an /r/ initial suffix and vowel deletion.

b. Metathesis fails to apply when a stem ends in a velar nasal and a /r/ initial suffix is attached.

Articulatory timing: Consonant clusters in the language are ordered in terms of their place of articulation. The place of the first consonant is consistently posterior to the following consonant (Hume 1997).

Aerodynamic Considerations (Hume 1997): The articulation of the consonant [m] and [w] is posterior to that of the consonant [r]. By metathesis, the posterior consonant comes before the anterior consonant. This pattern may have an explanation in the aerodynamics of egressive airflow. For sequences involving stop consonants at least, ordering the articulations in a manner consistent with the direction of airflow may provide greater air pressure for the production of the release bursts. The motivation is less apparent in the case of fricatives and sonorant consonants, sounds for which a release burst is of lesser importance or entirely lacking. Pattern congruity may be of relevance in this respect, however (see e.g. Maddieson 1984). If a language makes use of a posterior-anterior ordering for a subset of consonants, it is reasonable to assume that the more economical language would be one in which this ordering is used for other sequences as well, even if they do not have similar aerodynamic requirements. In this regard, it is of significance that the articulations of all complex segments in DEg are also produced in the order posterior-anterior. In the case of labiovelar stops [k°p, g°b], Connell (1994), Ladefoged & Maddieson (1996) and Maddieson (1993) have shown, as noted above, that the dorsal closure generally precedes the labial closure. Similarly, in the case of labialized consonants such as [sw, lw, kw], while the articulations in such segments are assumed to be simultaneous phonologically, in terms of their phonetic realization, a secondary labial articulation is realized during the consonant’s release phase, hence, following the primary consonantal articulation. Consequently, for labialized coronals and dorsals, the articulatory timing of posterior-anterior is once again observed. Thus, given the potential aerodynamic benefits of the order posterior-anterior for stop consonants, in addition to the observation that the language also contains multiply-articulated segments for which similar timing considerations hold, generalizing the posterior-anterior ordering requirement to all sequences of consonants in the language may result in a simpler and potentially more learnable language.