Picture this: a college student, sitting somewhere in the middle of a classroom, taking down the notes from the slide as she sees it but at the same time adding what the teacher is saying (and she's expounding on something not written in the slide so it's doubly hard). She also hasn't read the book yet and sometimes the words the teacher is saying sounds like a foreign language.
Hianin? Hiadin? Hyaline? Ansaveeeh?
According to Nixon (2002), it is believed that as many as one third of all students are missing 33% of verbal communications in classroom discussions. Not because they can't hear the teacher-- but they can't distinguish what the teacher is saying. As any student will know, this can be incredibly detrimental to the learning experience and to the understanding of the lesson.
So what can be done about this situation?
When the student is able to, it is best to sit closer to the teacher and further away from other sources of noise ("Classroom positioning," n.d.). This would ensure that they are able to hear most of the direct sound coming from the teacher.
Figure 1. Path of Direct Sound in the Classroom
But the Direct Sound Path is not the only path sound takes within the classroom. There is also the Reflective Sound Paths. Sound radiates in the form of waves into all directions from the teacher until it encounters an obstacle such as the ceiling, the floor, a chair, or the walls (Seep, Glosemeyer, Hulce, Linn, & Aytar, 2000).
Figure 2. Path of Reflective Sound in the Classroom
The sounds that follow the Reflective Sound Paths have different ways of dying down. These include transmission, which is when the sound passes through the surface and into the space after it, absorption, when the surface absorbs the sound much like how a sponge would absorb water, reflection, when the sound strikes the surface and bounces away like a ball, and diffusion, when the sound strikes the surface and scatters into multiple directions (Seep, Glosemeyer, Hulce, Linn, & Aytar, 2000).
The problem with the Reflective Sounds is that it tends to produce an echo which would interfere with the next word if it's reverberation time is long. The reverberation time is used to determine how quickly a sound decays in the room. Ideally it would be around 0.4-0.6 seconds but in most classrooms, it takes around a second for the sound to die off (Seep, Glosemeyer, Hulce, Linn, & Aytar, 2000).
But other than the slight echoes in the classroom, noises not coming from the teacher also interferes with the direct sound of the teachers voice and can thus hinder the learning experience of the student. These noises can come from construction being done outside the room, extremely heavy rain outside, the noise of the electric fan or the airconditioner, or maybe even a seatmate chatting with their friend.
Figure 3. Ambient or Background Noise
Given all of these factors, what the student hears is dependent on the Signal-to-Noise Ratio of their seat in the classroom. This generally refers to the difference between the sound from the teacher that enters the student's ear and the background noise that also enters their ears. The optimum is to have an S/NR that is around +15 and the lower the number gets, the harder it is for the student to understand the teacher (Seep, Glosemeyer, Hulce, Linn, & Aytar, 2000). But as seen from the diagram below, the optimum is a little before six feet away from the teacher and that would not cover even half of an auditorium full of students.
Figure 4. Signal-to-Noise Ratio
So what does this mean for us?
It means that, as students, there will be times when we cannot hear much of what the teacher is saying, be it because of the echoes that bounce off the walls or the noises in the background. Sometimes, our knowledge on the subject would fill the gaps that our auditory senses miss out-- they'll replace unintelligible words with a word they know that might fit the context of the sentence. And, of course, we can always improve the classroom-- make the walls such that the noise from outside will not enter and more Reflective Sound is absorbed instead of reflected or diffused.
But that is not always an option. In certain schools in the Philippines where the walls are blackboards and there is the teacher is talking to students more than six feet away, the S/N ratio will be extremely low no matter what "improvements" will be made (unless, one builds a brand new classroom). There will be a lot of background noise that would interfere with their studies. Also, being at that age, the children might not have enough knowledge to find an appropriate word to fit into the context should they miss it because of the acoustics.
This is a loss in our learning experience and, in the long run, a loss of knowledge.
To raise the S/N ratio in the cheapest way possible, perhaps it is time to re-figure the traditional classroom setting where the teacher is in front of the class and only those in the front seat could hear her. Why not move the chairs so that there is an equal distance between the teacher and each student? Perhaps, the classroom can have small circles where tables would connect with each other and these small groups of students can learn on their own in certain discussions with the guidance of the teacher who roams around-- thus, they will all be able to hear each other and this may raise the S/N ratio.
Maybe. Perhaps. All these suggestions still have their problems, but there may come a time when we will figure out how to make the perfect classroom as an environment best suited for learning. Until then, we are left to turn to our seatmates when an indistinguishable word is uttered and whisper, "Ansaveh?"
Mike Nixion (2002). Acoustical Standards Begin to Reverberate. Acoustical Surfaces Inc. Retrieved from http://www.acousticalsurfaces.com/soundproofing_tips/html/control.htm
Seep, B., Glosemeyer, R., Hulce, E., Linn, M., & Aytar, P. (2000). Classroom Acoustics: a cesource for creating learning environments with desirable listening conditions. Technical Committee on Architectural Acoustics of the Acoustical Society of America. Retrieved from http://asa.aip.org/classroom/booklet.html
"Classroom Positioning" (n.d.) Cochlear. Retrieved from http://www.cochlear.com/wps/wcm/connect/sea/home/support/excel-at-school/classroom-positioning
[Untitled Diagram of Direct Sound] Retrieved from http://www.cochlear.com/wps/wcm/connect/ac5743d9-7535-494a-918b-2dc90128f3b1/classroom-positioning-1.jpg?MOD=AJPERES&CACHEID=ac5743d9-7535-494a-918b-2dc90128f3b1
[Untitled Diagram of Reverberation] Retrieved from http://www.trane.com/commercial/library/vol32_1/en32-1_fig3.jpg
[Untitled Diagram on Ambient Sounds] Retrieved from http://www.acousticalsurfaces.com/soundproofing_tips/images/trans_3.gif
[Untitled Photograph on a Public School in the Philippines] Retrieved from http://business.inquirer.net/files/2012/02/classroom.jpg
