The regions have the dialects that have not far from the Indonesian language. Not sure which one is the source of the language; the national language of Indonesian, or the local dialects.
When I visited Palembang, the capital city of South Sumatera, I heard the word of apo / a-po / that means what. Meanwhile in the Indonesian language the word apa / a-pa /, is the same meaning of what.
At the other side, a local dialect of Betawi, Jakarta, there is a word of Ape /a-pé /, in the same meaning of what. This word Ape / a-pé / has also found in local dialect in Bangka Belitung, the island of eastern Sumatera, across Palembang, near the South Chinese Ocean. The island as I have grown up and had research on it, still have the same word with lower vowel e (ə); ape /a-pe/, the meaning still the same, what. We can find the word ape at the western region of Bangka Island.
In associating these rich vowels with our auditory learning system of vowels according to G.C. Simpson with his phonetically in the technique of our speaking organs.
Apa / a-pa / a, the air suppressed through the vocal folds, mouth open wide, the tip tongue upper than the upper teeth
Apo / a-po / o, circled upper and lower lips
Ape / A-pé / the é, the sound will emerge almost the same way as others, but the upper and down lips are stretching to the sides, our tip tongue is upper the lower teeth and our mouth is open.
Ape /a-pə/ this lower e source of sound will be the same way as other, having the same lips position as the sound é, but the mouth is open smaller, and our upper and lower teeth are going down when we pronounce it.
Written by, Mirna Marini D. Arifin
Linguistic and Visual Anthropology
Based on linguistic research