Automation of Subjective Measurements of Logatom Intelligibility in Classrooms

A great number of rooms are dedicated to a voice communication between a singular speaker and a group of listeners. Those rooms could be as small as meeting room and classrooms or larger like auditoriums and theatres. There is a major demand for them to assure the highest possible speech intelligibility for all listeners in the room. Classrooms are an example of rooms where a very good speech intelligibility is required (a teacher talks to a group of students who want to understand the teacher’s utterance). To determine the intelligibility degree (its maps) of rooms, it is necessary to take measurements in many points of those rooms. The number of measurement points depends on room’s size and precision of created intelligibility room’s maps. Despite of the crucial progress in the instrumental measurement techniques, the only reliable method subjective speech intelligibility measurement is still very time consuming, expensive, demanding high skills and specially trained group of listeners. The first part of this chapter presents the idea of speech intelligibility subjective measurements. The measurements with properly trained team are taken in described standards, conditions have to be controlled and repeated. The subsequent sections of the chapter are focusing on one of the classic subjective speech intelligibility measurement method in rooms (classrooms) and its automated version which is named as the modified intelligibility test with forced choice (MIT-FC). Finally, in the last section of the chapter, there compared results of subjective speech intelligibility measurements in rooms taken with classic and automated methods are and the relation between intelligibility taken with the forced choice method is given as well. The presented relation let us compare results taken with both methods and use relations known from earlier research carried in domain of speech intelligibility. However, the biggest advantage of the speech intelligibility measurement automation is the shortening of measurement time and the possibility of taking simultaneous measurements in several points of the room. The result of speech intelligibility is obtained just after the end of measurements, it is then possible to obtain the intelligibility map in few minutes. Of course the precision is growing with number of listeners in particular points.