3.3.1 With reference to the pronunciation test, they were divided into three main parts with a total of 30 items: part 1 for a pronunciation test of the // initial sound with 10 items, part 2 for a pronunciation test of the // medial sound with 10 items, and part 3 for a pronunciation test of the // final sound with 10 items,. After being examined and approved by three experts, ten items were selected for each part of the pronunciation test with a total of 30 items used for testing the 25 students’ problems in pronouncing // sound in three positions.
3.3.2 For the in-depth interview, they were divided into one question of “what the guidelines on correction in pronouncing // sound”, consisting of three positions: initial, medial, and final. The in-depth interview had its face validity examined and approved by three experts, and it was used with three native speaking instructors and two Thai instructors.