Influence of indoor and outdoor noises on the speech intelligibility in classrooms

Abstract

There are many noise sources inside the classrooms such as heating, ventilating, and air-conditioning(HVAC) noises. Also, there are outdoor noises near classrooms such as road traffic noises. Under these situations, teachers are using loudspeaker system in order to enhance the speech transmission. The present study aims to investigate the students’ subjective responses to teacher’s speech under many different noise situations. in order to this, questionnaire survey was undertaken to 60 students in two different classrooms. They were asked to mark their subjective listening comprehension and speech intelligibility in 5-points scale at every cases when three conditions were changed including opening status of doors and windows, operating HVAC system, and usage of loudspeaker system. Also, sound levels were measured in each case. As a result, it was found that only 17% of subjects responded that they were prevented from noises from outdoor and HVAC system. Also, it was responded that using loudspeaker system can enhance the listening conditions 2.7 times more than normal condition. Nevertheless, there are 33% of negative responses to loudspeaker system due to the artificial tone of speech. Thus, it can be concluded that indoor and outdoor noises cause by opening windows and operating HVAC system do not affect student’s speech intelligibility much in general cases, Also, using loudspeaker system in small classroom should be used cautiously considering students’ preferences.