Noise Pollution and
Classroom Acoustics
Marc Hodapp
Rory Moulton
Kari Ricker
Goals

Original goal
– Determine noise levels in local classrooms

Final goals
– Improve local classroom acoustics
– Develop noise reducing materials using
recyclable resources
Objectives

Objectives
– Determine existing local classroom
acoustical conditions
– Make recommendations to improve local
classrooms
– Develop innovative acoustical treatments
from recycled material that would also
apply to other similar buildings
Negative Effects of Poor
Classroom Acoustics

25% to 30% of teacher’s verbal
communication is not heard

Lowered reading comprehension scores

Achievement scores below grade levels
Reading Comprehension
UK, Spain, & Netherlands, 2003
Reading Comprehension Scores
100
0
Aircraft Noise, dB(A)
Modified from http://aje.oxfordjournals.org/cgi/content/full/163/1/27
n = 2000 students
Standardized Grade
Equivalent Test
Los Angeles, CA, 2001
Modified From http://www.quietclassrooms.org/library/ICA2001.htm
n = 1406 students
Population Distribution
Population Distribution in Puerto Rico
Living in
Metropolitan Areas
(95%)
Not Living in
Metropolitan Areas
(5%)
Population Distribution in the United States
Living in
Metropolitan Areas
(80%)
Not Living in
Metropolitan Areas
(20%)
Methodology Part One:
Researching

Archival research
– Researched effects of excessive noise
– Researched current acoustical solutions
– Investigated recycled materials on island

Interviews
– Acoustical Engineer
– Waste Management Specialist
– Industrial Engineer
– Mechanical Engineer
Methodology Part Two:
Selecting Classrooms


Obtained permission from the Puerto
Rico Department of Education
Visited four local junior high schools
– Located two classrooms in each school
One classroom in noisiest section of school
 One classroom in quietest section of school

Methodology Part Three:
Noise Measurements

Following ANSI standards
– Used A-weighted time averaging sound level
meter

A-weighted: Noise as perceived by humans
– Recorded six separate readings of noise levels
Every three seconds for thirty seconds
 Noted background noises during noise level spikes

Methodology Part Three:
Noise Measurements

In all visited schools
– Recorded two unoccupied classrooms
One reading with unoccupied adjacent rooms
 One reading with occupied adjacent rooms


In one visited school
– Measured an additional room
With air conditioner on
 With air conditioner off

Methodology Part Four:
Classroom Profiling

Outdoors
– Photographed school grounds
– Measured distances to noise sources

Indoors
– Calculated reverberation time
Measured classroom dimensions
 Noted classroom objects’ material

– Distributed teacher surveys
Understanding the Results

Noise
– Originates from inside or outside
– Travels as a sound wave
– Measured in decibels (dB)
– Classroom levels should be less than 35
dB on average
Understanding the Results

Reverberation time (echo)
– Can be estimated
Assuming Sabine room
 Using absorption coefficients

– Can be measured

Using a sound level meter
– Units are in seconds
– Classroom time should be less than .6
seconds
Reverberation Example
www.reverberationtime.com
Rafael Martinez Nadal
(RMN)


Located in Guaynabo
Surrounding the school:
– Bus station
– High traffic road (most noise)
– Farm
– Courtyard
Dr. Cesareo Rosa Nieves
(CRN)


Located in the San Juan area
Surrounding the school:
– Construction site on two sides (most
noise)
– Elementary school
– Housing
Sabana Llana (SL)


Located in the San Juan area
Surrounding the school:
– High traffic street (most noise)
– Courtyard with a basketball
court (most noise)
– Housing
– Parking lot
Republica Del Peru (RDP)


Located in the San Juan area
Surrounding the school:
– High traffic road (most noise)
– Housing on two sides
– Basketball court
and playing fields
Results
Rafael Martinez Nadal Room 1
(Adjacent Room Occupied)
Sound Level (dB)
75
70
Reading 1
Reading 2
65
Reading 3
Reading 4
60
Reading 5
Reading 6
55
50
1
2
3
4
5
6
Reading Number
7
8
9
10
Results
Rafael Martinez Nadal Room 1
Adjacent Room Occupied
Comparison of Average Noise Levels
70
Sound Level (dB)
60
Reading 1
50
Reading 2
Reading 3
40
Reading 4
30
Reading 5
Reading 6
20
ANSI Suggestion
10
0
1
Results
Rafael Martinez Nadal Classroom Comparison
Chart
Rafael Martinez Nadal Classroom Comparison Chart
62
Room 1 (loud),
occupied
adjacent
Sound Level (dBA)
61
60
Room 1 (loud),
unoccupied
adjacent
59
58
Room 2 (quiet),
occupied
adjacent
57
56
Room 2 (quiet),
unoccupied
adjacent
55
54
1
2
3
Average Reading Number
4
Results
Occupied Adjacent Classroom Average Noise Level
CRN 1
CRN 2
70
Sound Level (dB)
60
RMN 1
RMN 2
RDP 1
RDP 2
SL 1
SL 2
ANSI
50
40
30
20
10
0
1
Results
Unoccupied Adjacent Classroom Average Noise Level
CRN 1
CRN 2
RMN 1
RMN 2
Sound Level (dB)
70
60
50
40
RDP 1
RDP 2
SL 1
SL 2
ANSI
30
20
10
0
1
Results
Average Reverberation Time (Open Windows)
1.6
RT (seconds)
1.4
CHART KEY
1.2
RMN: Rafael Martinez Nadal
CRN: Dr. Cesareo Rosa Nieves
SL: Sabana Llana
RDP: Republica Del Peru
1
0.8
0.6
0.4
0.2
0
RDP 2 CRN 1 RMN 2
SL 2
RDP 2 RMN 1 CRN 2
School Name and Classroom #
SL 1
ANSI
Med On a scale of 1 to 10, what is the noise level in your
classroom?
Teacher Results
10
8
6
10
4
7
CRN
7
6
2
0
RDP
RMN
School Number
SL
Teacher Results




98 percent reported that there was
outdoor noise during class hours
89 percent reported that they have to
speak over the outdoor noises
76 percent recorded that they hear
noise from other classrooms
73 percent recorded that they have to
speak over interior noises
Teacher Results
Conclusions:
Classroom Acoustics





Sound levels exceed ANSI, 2005
recommendations
Reverberation times exceed ANSI,
2005 recommendations
People cause the most frequent
increases in noise levels
Noise levels vary within schools
Teachers in all schools agree that
noise levels are high
Results
Sound Absorbing Material

Polyester as a sound absorber
http://kr.gobizkorea.com/att/english/offer/PSF-HC1.jpg
Results
Sound Absorbing Material
Results
Sound Absorbing Material
Results
Sound Absorbing Material
Conclusions:
Acoustical Tiles





Inexpensive fibers
Low initial investment
Pioneering production
Potential for profit
Potentially large market
Recommendations for The
Department of Education

Phase Number One: Understanding
Noise
– Purchase low-cost sound level meters
– Initiate an island wide sound study
– Collect data in a standardized manner
– Identify the schools and areas with the
most noise problems
Recommendations for The
Department of Education

Phase Number Two: Developing
Standards
– Consult an Acoustical Engineer
– Develop and adopt acoustical standards
Follow ANSI
 Develop standards for Puerto Rico

Recommendations for The
Department of Education

Phase Number Three: Beginning the
Process of Change
– Urge schools to consider our low-cost
solutions
– Consider allocating funds to acoustically
treat classrooms
– Work with the Environmental Quality
Board to reduce noise outside of schools
Recommendations for All
Puerto Rican Public Schools

Step Number One: Know Your Noise
– Take sound level measurements
Interactive learning experience
 Involve students and teachers

– Locate the loudest and quietest sections
– Identify the major sources of noise
Recommendations for All
Puerto Rican Public Schools

Step Number Two: Involving Students
– Educate students about noise
– Demonstrate different sound levels in
class
– Inform students when their voices are
loud
Recommendations for All
Puerto Rican Public Schools

Step Number Three: Designate Quiet
Zones
– Determine which areas are quiet zones
Hallways
 Classrooms
 Libraries

– Designate one or two break rooms

Located in loudest section
– Designate a gathering area outdoors

Located as far away from classes as possible
Recommendations for All
Puerto Rican Public Schools

Step Number Four: Sound Solutions
– Low Cost
Open windows
 Close doors
 Limit use of mechanical devices

– Commercial Solutions
Install acoustical tiles
 Seal windows
 Install central air conditioning

Summary of
Recommendations






Locate noise sources
Rearrange classrooms
Educate students about noise
Seperate break areas from classes
Open windows to reduce reverberation
Limit the use of mechanical devices
Thank you







Department of Education
University of Puerto Rico
Selected schools
Interviewees
ADS
PRIDCO
REMA