Datapoint Lingala/Geographic variation: phonology
Northwestern Lingala has 7 vowel phonemes, making the additional distinction between the mid-close and the mid-open front vowel and the mid-close and mid-open back vowel.
Northwestern Lingala has less tendency to shift the rounded mid-close back vowel upwards than is the case in Southwestern Lingala (spoken in and around Kinshasa and covered in this Atlas).
Values 
Limited
- Confidence:
- Certain