Classroom Acoustics
Inferior acoustics is an invisible problem that has far-reaching implications for learning, but is easily solved. Excessive noise and reverberation interfere with speech intelligibility, resulting in reduced understanding and therefore reduced learning. Many educators feel it is important to improve acoustics in classrooms used by children with hearing problems, but unnecessary to do so in those used by students with normal hearing. Yet many populations of students with "normal hearing" also benefit from better classroom acoustics. These include students with learning disabilities, those with auditory processing problems, and those for whom English is a second language.
Read a short non-technical article about Myths & Facts of Classroom Acoustics.
Click this link to read a generalized description of classroom acoustics
Another group for whom learning is especially dependent on good acoustics is young children, who are unable to "predict from context." With their limited vocabulary and experience, if they miss a few words from a teacher’s lecture, they are less able than older students to "fill in" the missing thoughts. Given these considerations, it is clear that a wide range of students benefit from improved classroom acoustics. The best way to solve acoustics problems is to prevent them beforehand, not correct them after the fact. During the design process, acoustics problems can usually be avoided with a bit of forethought and a different arrangement of the same building materials. Renovation of poorly designed classrooms is much more expensive. Even then, the cost of renovation is small compared to the social costs of poor classroom acoustics that impair the learning of millions of children.
What are your classroom acoustics? Take the time to listen to the sounds of your classrooms.
N~O~I~S~E
The term “noise” (or variations—background noise, classroom noise, etc.) refers to any auditory disturbance that interferes with what a listener wants to hear (Finitzo-Hieber, 1988). The source(s) of the noise may or may not be within the classroom itself. Most classroom noise sources
arise from outside the building and intrude through exterior walls and windows,
are generated by heating/ventilating and air-conditioning (HVAC) systems,
intrude from hallways and adjacent rooms, and
are generated from within the classroom by computers and appliances as well as by the children themselves.
American National Standards Institute Standard S12.60 Classroom Acoustics New construction and renovation
Reverberation (echo) minimum of 0.4 seconds and maximim of 0.6 seconds for classroom size under 10,000 cubic feet and 0.7 seconds for classroom size between 10,000 and 20,000 cubic feet.
Ambient (background) noise less than 35 dBA (weighted scale)
Understanding Sound To better understand how sound, found in the classroom, affects a student’s ability to hear and learn, first become familiar with the attributes of sound. Direct Sound The sound of a teacher’s voice traveling directly from the teacher to the student is direct sound. It is always beneficial in terms of speech intelligibility because it is not affected by anything in the room, making it clear and distinct. Reflected Sound Reflected sound takes longer to reach the listener than direct sound because its path to the listener is longer. Reflected sound can be good or bad depending on the time delay. Reverberation Time The overall effect of reflected sound is called reverberation, and the time required for reflected sound to become inaudible is called reverberation time. Short reverberation times are good for speech intelligibility. Background Noise Any sound that is generated outside the building, such as playground activity, traffic and planes can be considered background noise. It generally intrudes in the classroom by way of the windows. Within the building, an HVAC system and corridor noise can contribute to background noise. Descriptions above provided by Armstrong Commercial & Industrial Ceilings Corp. To further understand the classroom acoustic attributes, watch the video clip entitled "Straight Talk." Click here to access the Armstrong.com web site and then click on the Straight Talk video clip. This is not an endorcement of Armstrong or it's products.
Steps to Producing a Good Listening Environment
Did you know . . .
that speech intelligibility in many classrooms is 75%, i.e. listeners with normal hearing are missing one of every four words?
that up to 30% of primary students have some hearing loss, particularly during cold/flu season?
that there is an American National Standard for acoustic criteria and design requirements of classrooms?
that classroom noise impacts the academic success of ALL students?
that young students, English language learners, and students and teachers with hearing, language, or learning problems are at a greater disadvantage from poor acoustics?
that classroom noise impacts teacher absences?
that children need the teacher’s voice to be at least 15 decibels (dB) louder than interfering sounds?
that classroom sound-field amplification systems facilitate inclusion and response-to-intervention (RTI)?
that classroom sound-field systems reduce vocal strain of teachers and reduces absentee rate by as much as 36%?
How do you provide a good listening environment?
1. Provide sound barriers around classroom with partition walls extending all the way to the structural deck (floor above or roof).
2. Use dropped acoustic panel ceiling to reduce sound reverberation (echo).
3. Provide a barrier to exterior noise with double-paned, well sealed windows and solid doors with tight-fitting, sealed frames
4. Provide a “quiet” space, less than 35 dBA of noise from internal sound sources such as ventilating systems, computers, video projectors.
5. Use classroom management strategies to control noise from occupants of the room.
6. Arrange classroom learning centers to provide sound defusion and reduce distraction.
7. Amplify the teacher’s voice to raise the signal-to-noise ratio, which improves speech intelligibility and reduces vocal strain.
Why should you use your classroom amplification system? See the answers!
