Acoustic Analysis of the Effect of Educator’s Face Direction on Students’ Phonetic Recognition

For a lecture in a classroom, it is empirically known that the students are more engaged in the lecture and exhibit a better understanding of the content of that lecture. We hypothesize that the effect is due to the quality of sound produced by the teacher and received by the students. Specifically, the voice spoken by a teacher facing toward students will have a better acoustic characteristic than the voice spoken opposite to the students, which contributes to the comprehension of the words spoken by the teachers. To this end, we first conducted experiments to examine the difference in sounds reaching directly to the students and after bouncing on a wall in some typical classroom environments. Second, we conducted experiments to examine the difference in the number of remembered words from spoken ones. The experiments compared the cases between the word-speaking teacher's orientations either to the students or opposite to the students. The results from these experiments showed that the sound heard from a teacher facing toward students in a classroom has a higher acoustic pressure level at around 800-900Hz, which is close to the first formant. Also, the memorizing test showed that the teacher's voice contributes to improving the number of remembered words from the words spoken by the teacher. Our results show the importance of looking at students during lectures in a classroom. Also, it suggests an automatic tool to count the frequency of a teacher to look at students, which will help the teacher to self-evaluate his/her lecture.