Akan Twi has 10 vowels. All the 10 vowels are represented in Adinkra Alphabet as shown below. Akan Twi has two different A/a (not ah) sound. One is pharyngeal and the result of advance tongue root (ATR) and the other is glottic. Glottic A/a sound is represented in Latin as E/e.
There are two subset of vowels in Akan known as +ATR and -ATR. Each subset of vowels contain 5 vowels in Adinkra Alphabet. The phenomenon in which vowels in each subset of 5 occurs together or changes the preceding vowel to a vowel within each subset is known as vowel harmony.