We think of every detail in preparing our children for the future. It is our dream to give them the best education possible. The architects spend months designing the most beautiful and functional building. We give them what we feel is the greatest atmosphere in which to learn. We hire the most qualified people. We equip the schools with the most up to date technology available. We open the doors, the class begins, and then you hear “Can you repeat that? I couldn’t hear you.”
We make sure in the performing arts areas of the schools that there are outstanding acoustics. After all, in this facility the students are graded on their performances and communication abilities. But what about having the best acoustics in our classrooms where their learning performance is being evaluated? Classroom learning typically involves intensive speech communication between teachers and students or students and their peers. The effectiveness of this communication, and hence, the effectiveness of the learning environment is influenced by acoustical conditions in the classroom. Good classroom acoustics greatly facilitates learning. Test scores are affected by what is learned.
Can You Hear Me Now?
Many students today are dealing with learning disorders, learning English as a second language and hearing impairments. More importantly are the younger students who have limited vocabularies. They are less able to fill in the missing words or phrases when they do not hear clearly. To achieve speech intelligibility in learning spaces means increasing understandability, not just audibility. Debbie Pye, the Armstrong Architectural Representative for Architectural Interior Products says, “In communications, it is more than hearing, it is being able to understand what is being said. When students cannot understand the concept, they may not learn.”
Improving speech understanding involves controlling the classroom’s background noise and reverberation time. Background noise is made up of all the unwanted noises in a classroom such as noises from the air handling system, the squeaky chairs and desks, traffic outside, and kids passing in the hallway, to name a few. When this background noise in the classroom is louder than the teacher’s voice, the students will have difficulty understanding what they are being taught. The reverberation time is the time it takes reflected sound to become inaudible. When the reverberation time is long, the first word spoken is still audible when the next word in a sentence is spoken. This overlap of words and syllables makes it difficult to understand what is being said. Both the background noise level and the reverberation time in a classroom can be reduced, and intelligibility improved, by adding sound absorptive materials to the room.
A New Standard
To help with the acoustical designing of classrooms, a standard was developed by educators, acousticians, manufacturers and others to act as a guideline for preferred background noise and reverberation levels in a classroom. This standard is ANSI S12.60 Acoustical Performance Criteria, Design Requirements and Guidelines for Schools. ANSI Standard S12.60 for Classroom Acoustics addresses the issues of both reverberation time and background noise and their effect on speech intelligibility by placing maximum permissible levels on each. Under the new standard, the maximum reverberation time in an unoccupied, furnished classroom with a volume under 10,000 a cubic feet is 0.6 seconds, and 0.7 seconds for a classroom between 10,000 and 20,000 cubic feet. The maximum level of background noise (one-hour-average A-weighted steady background noise level) allowed in the same classroom is 35 decibels (dBA). Some classrooms today have reverberation times as high as 2.8 seconds and background noise levels as high as 66 decibels. However, by following ANSI S12.60 guidelines, acoustical problems can be avoided and classrooms with a high degree of speech intelligibility can be built.
Designing classrooms to meet the acoustical requirements of ANSI 12.60 is neither difficult nor costly. The key is including acoustic concerns early in the planning and designing stages. Armstrong Ceilings makes this an effortless task. With their interactive reverberation tool on their Web site, you can calculate reverberation time and hear the difference in five steps. You describe the space, see the recommended guidelines, select the surface materials and the program will calculate the current reverberation time. You select treatment materials for your space to meet the reverberation recommendation and hear the difference, before and after!
Sounding Off
West Virginians do want the best educations and facilities for their children in which they can learn. Billions of dollars are invested in West Virginia school facilities. Since 1989, our state has built 127 schools funded with SBA financial support. The state of West Virginia has contributed $1.06 billion and the counties have contributed $948 million to building new schools. There will be three new schools opening this fall. With this being said, the cost of having proper acoustical levels in the classrooms so that children can hear and understand what is being taught, seems like a small investment that each education system should value.