This may also have entailed that much of the material recorded was originally uttered in a declamatory, rhetorical, or performance style.
As analyzed by Sapir,[8] Jabo was represented as possessing four phonemically distinct pitch levels (or registers),[10] independent of phonation type or supraglottal articulation.
This meant that there could possibly be sixteen distinct, segmentally-identical short monosyllables with significative pitch contours—more if long syllables were admitted.
The not-uncommon word types CVː (CVV) and CVCV could potentially have 256 possible prosodic contours, each with a different dictionary meaning for the same three or four segments.
This last possibility may make it simpler to rationalize the apparent markedness of the extreme vowels [u] and [i], which are said always to be "turbid".
Since the articulations involved are probably to a degree mutually exclusive (velic and pharyngeal), and since they seem to contribute similar auditory components (nasalization and "turbidity"), they are more likely to be allophones resulting from assimilation.
However, the possibility exists that Sapir's analysis is overdifferentiated (i.e., the transcription is too "narrow" to claim tonemic status).
This tonal system implies an extremely high level of significative functional load to borne by pitch in the language.
Glebo (Seaside Grebo) had possibly the earliest literary history of any speech variety in the Cape Palmas area, dating to the time of the missionary efforts associated with Maryland in Africa.
This choice may be due to Jabo's preserving a number of "archaic" features from the proto-language, if it is indeed the case that its highly differentiated phonology reflects a common stage of development.
The pedagogic principle would be that it is easier to teach across heterogeneous groups from a differentiated writing system (to a variety in which the contrast has been merged), than the reverse.
Students speaking the less differentiated variety need only learn to ignore the "superfluous" distinctions as heterographic homonyms, rather than memorizing numerous, seemingly random heterophonic homographs.