# Classroom Amplification Makes an Academic Difference by 7g35w6

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```									Classroom Amplification Makes
James C. Blair, Ph.D.
Utah State University
 Ray, Sarff, and Glassford, 1984
 Amplifying a classroom helped children score
 Gertel, McCarthy, and Schoff, 2004
 Amplifying a district helped children improve
their academic achievement test scores by as
much as one grade in one year
 Especially helped the Title I students and ESL
students
How Important is
Listening?
 Two-thirds of a student’s day
consists of listening to and
participating in spoken
communication
 Listening environments need to be
free of acoustic and non-acoustic
barriers
Other Findings
 Teacher absences due to loss of voice or
fatigue is reduced
 Student’s interest in and attention to
teacher improved
 Behavior problems are reduced
 Fewer questions asked that are for
clarification purposes
 Increased student participation in class
when a pass-around microphone is used
The Problem
 As talker moves away from the listener the
signal decreases 6dB every time the distance is
doubled (distance is a problem)
 Start at 65dB HL, 6” from mouth, at 1 foot the
intensity is 59dB, at 2 feet the intensity is 53dB, at 4
feet 47dB, at 8 feet 42 dB, and at 16 feet it is 36dB
 Noise is a problem
 A normal listener at the back of the room, if it was
very quiet, would have a signal-to-noise ratio of +1, if
no children were in the class.
 With children the background noise is going to be at
A second problem is
reverberation
 Reverberation occurs when sound
encounters a hard wall
 Sound bounces around a room
 The effect of reverberation is slurring of
speech as you move away from the talker
 Normal listeners do best when reverberation
times are below .6 seconds
The Overall Problem
 When noise, distance, and reverberation are
combined the result is speech is difficult to
understand
 For normal listeners a +6dB signal-to-noise ratio leads
to a 9% decrement in speech recognition
 When a reverberation time of .7seconds is combined
with a signal-to-noise ratio of +6dB word recognition
scores decrease by as much as 20%
 A student at the back of the room has a huge
So Why Don’t We Complain
 It’s always been this way
 We figure out strategies
   We   get notes from the teacher/presenter
   We   read the text or the references
   We   talk to our friends about what was discussed
   We   sit close to the front of the room
 We would never allow children to be taught
in a dark room, but we will allow them to
be taught in a room in which they can not
hear well
Study
 Five different classrooms used in the study.
 All were similar in size
 30 to 35 feet deep
 32 to 40 feet wide
 All met ANSI standard for noise and reverberation
 RT 60 .32
 Noise Criteria 32 dB
 Four teachers used classroom amplification, one did
not
 A pass-around microphone was used in one classroom
regularly, but either sporadically or not at all in the
other three classrooms
Procedures
 A measuring microphone was placed on a
tripod, positioned at the level of the child’s ear
(placed near a child’s ear)
 Measurements were made at 9 different
locations in each room (back center, left back,
right back, left center, middle center, right
center, front right, front left, front center)
 Measurements were made in 10 minute
increments
 The Time, Energy, Frequency (TEF) system was
used to obtain measurements
Signal-to-noise ratios with
infrared classroom amplification
 Obtained signal-to-noise ratios were on
average between +13 to +20 dBA at
every position measured in the rooms
 One classroom was not fit with a
classroom system and all other teachers
were asked to turn off their systems for 5
minutes during the data collection.
 The average signal-to-noise ratios were
between +2 and +6 dBA without
amplification
Actual Conditions
(unamplified)
random order around the classroom.
 Average sound level at the microphone based
on distance away from the microphone.
   2 feet - 59dB
   3 feet - 56 dB
   6 feet - 55 dB
   12 feet - 46 dB
 There are times when the sound level is 13
dB less intense than at other times.
Results: Unamplified
Classroom
 Teacher’s measured vocal intensity;
 Front of the room at nearest student’s desk
was 58 dBA, with a range of 50 to 65 dB
 Middle of the room at child’s desk, the level
was 52 dB, again with a range of 40 to 60 dB
 At the most distant point, this is measured as
being 18 feet from the most common place
from which the teacher presents information,
was 48 dB with a range of 40 to 52 dB
Implications
 The results indicate that at the front of
the room the average signal-to-noise
ratio was +15 with a range between +8
and +20
 In the middle of the room the S/N ratio
was 8 dB with a range between +1 and
+10
 At the back of the room the S/N ratio
was 0 dB with a range of -15 to +6 dB
Implications (continued)
 Depending on where the child is seated at any
given time changes the amount and quality of
input available
 There are times when everything is audible and other
times when information is not audible at all
 At best the input to children is variable
 The child who has any kind of hearing problem
is getting at best variable auditory input (about
10% of the students)
 Remember this room meets ANSI standards
Amplified Classrooms
 In these classrooms all speakers were in the
ceiling, providing direct sound to most of the
children.
 No matter where the child was seated in the
room they were getting no less than a +10
 When the hand-held microphone was used the
same advantage was present for the children as
for the teacher, when not used it was like the
results in an unamplified room.
Results (continued)
 Observations:
 In the classroom with no amplification
 Many students did not listen well when the
teacher was talking
 After the teacher explained an assignment on a
poem and the children started to work, the
teacher noticed one child looking around as if
trying to discover what to do. When the teacher
student said, “Oh, I thought you were talking
about some kind of foam and I didn’t know what
you wanted us to do.”
 Little differences can make for a great deal of
confusion
Logan City School District
 Few classrooms have used systems for many
years
 Middle School was convinced that a system for
their school was important
 Opted not to repave a parking lot and used the money
to purchase audio enhancement for all instructional
classrooms
 Legislature provided money for technology
 Superintendent and Board decided to use the bulk of
the money to put audio enhancement in every
classroom in the district
Current Findings in Logan
City Schools
 Three-hundred five teachers (K-12) were
surveyed
 One-hundred sixty-five responded (54%)
 Do you have classroom amplification in your room?
 93.9% yes; 6.1% no
 Do you personally use the equipment?
 89.6% yes; 10.4% no
 How often do you use the equipment?
   All day, every day: 48.2%
   When presenting information: 28.4%
   Occasionally, for special presentations: 10.6%
   When I think about it: 5.7%
   Other: 7.1% (don’t use it when there are groups in the
class)
Findings (continued)
 Do students use the microphone?
 Yes, 59.1%
 No, 40.9%
 How often and under what conditions?
 Pass the microphone around during class discussions:
3.3%
 Use the microphone when presenting in front of the class:
68.5%
 They use the microphone whenever they are talking to
the whole class: 17.4%
 Do guests in the classroom use the system?
 Yes: 62.3%; No: 37.7%
 How often and under what conditions?
 When reading a story to the children: 29.5%
 When presenting information to children formally: 61.1%
 Whenever a guest talks they use the system: 61.1%
Findings (continued)
 What is your impression of the system?
 I believe students are more attentive: 80.1%
 I can control classroom behavior more effectively: 65.2%
 It helps children in my class perform better: 53.9%
 The children like it when I use the system: 65.2%
 Because I don’t need to talk loud, or yell, I am less tired
at the end of the day: 66.0%
 I don’t think that the system helps at all: 5.7%
 How important do you think an amplification
system is in a classroom?
   Detrimental: 0%
   Not too useful: 8.6%
   Useful: 13.2%
   Quite useful: 11.8%
   Very useful: 35.5%
   Essential: 30.9%
How to make it better
   Put it in the gym: 2
   Need hand-held mic: 19
   Cuts out all the time: 2
   Mic too heavy: 18
   Need smaller mic: 15
   Needs to connect to all systems: 13
   Mic Reverberates/Feedback: 6
   Too soft: 2
   Dead places in the room: 1
   Too loud: 1
   I have a loud voice, don’t need it: 2
   I wear it for hard of hearing child: 2
   We need complete technology classrooms: 2
How can we make it better?
(continued)
 We need someone to maintain it and
 I love it: 6
 It is wonderful: 3
 Amazing: 1
 Nothing: 2
Some Considerations
 Installation of classroom amplification follows no
systematic procedure.
 In most states they are installed by the companies
 They are fit subjectively
 We are finding considerable variability across
classrooms and we have had to retrofit a number
 Many teachers will not wear the systems
   Too loud
   Does not work well
   Unwieldy
   I rarely teach the whole class at one time
   What to do when it does not work well
   I forget to put it on
   Microphone is too heavy and gives me a headache
Unresolved issues
 We know that anything is better than
nothing (unless it is not loud enough to
make a difference)
 We don’t know what is truly feasible in a
classroom (research says +15)
 Comfort
 Feedback
 Overflow
 We are not sure what is usual (study in
process says we are at about +8)
Student’s Opinions (N=258)
 It is easier to hear the teacher
 It is easier to listen when the teacher is talking
 “I like it when the teacher uses the system”
 “I feel that what I have to say is important”
 “I feel listened to when I can use the
microphone.”
 Where it is used, all student respondents had
of sound enhancement
Teachers’ Opinions (4 large
school districts)
 Students are more attentive
 Teachers can project their voices more easily
 Teachers feel less fatigued at the end of the day
(no need to talk loud or yell)
 Teachers experience less vocal strain
 Teachers report that students like it when they
use the system
 Teachers believe that students achieve at a higher
level
 Of all the equipment in the schools audio
enhancement is ranked as first or second as ”the
piece of equipment that has the greatest direct
influence on learning”
Does it matter where the
speakers are located?
 Choices:
   Speaker in the front of the room
   Speakers on the walls
   Speakers in a cluster
   Speakers in the ceiling
 Any speaker is better than none
 Provided they are turned up loud enough to improve the
signal-to-noise ratio
 The best placement is in the ceiling so as to be over the
 This arrangement provides the most consistent sound to
every child in the room.
 Other arrangements provide variable intensity as the child
is moved away from the speaker
Classroom Amplification Makes