A sound enhancement system (SES) consists
of a wireless microphone that amplifies the teacher’s
voice 8-10 decibels, and evenly distributes that voice through
speakers strategically placed around the classroom (ideally
located in the ceiling). These systems usually come with a
hand-held microphone for the students to share when speaking
aloud, so that student’s can also benefit from hearing
This even distribution of the speaker’s
voice creates a positive Signal-to-Noise ratio (SNR) of approximately
+15 dB in ALL listening areas of the classroom. Essentially,
every child in the classroom gets a “front row seat.”
Please note: the term
Sound Enhancement Technology or Sound
Enhancement System (SES) is often referred to as
sound amplification, sound distribution, and sound field technology.
The terms can be used interchangeably; however, we prefer
the term "enhancement" because it is a more accurate description
of the overall benefits. This technology enhances the quality
of the teacher's voice, enhances the student's acoustic accessibility
to their teacher and peers, and therefore enhances the learning
experience and subsequent academic potential.
Research has found that a student’s ability
to learn and academic performance are negatively affected when the
teacher’s ability to verbally communicate is blocked or muddled
by overwhelming background noises. It is crucial for students to
hear what the instructor is saying in order for effective learning
to take place. Therefore, since we cannot do anything to speed-up
the development of children’s auditory abilities, nor reduce
the number of “at-risk” students, it is abundantly clear
that we must do something to either improve or compensate for the
It would seem logical that the best solution for overcoming the
adverse effects of noise would be to attenuate it at its source.
Noise is controlled in one of two basic ways. It is either insulated
from the learning environment by some type of barrier, or it is
eliminated. This is what the Acoustical Society of America has attempted
to do in developing the acoustical design standards under the American
National Standards Institute. However, there are two problems with
trying to control the background noise alone.
First, it is not always fiscally feasible to retrofit/remodel every
classroom with solutions designed to engineer out troubling noise.
This is one reason why in 2002, the International Code Council (ICC)
did not adopt the ANSI standards for inclusion in the 2003 International
Building Code. It was also not adopted due to concerns over realistic
attainment of those specifications. The LAUSD study validated those
concerns by reporting background noise levels never dropping below
43 dBA in the occupied classroom, except during silent reading periods.
Therefore, spending money to reduce the building-generated noise
is nonproductive once that noise falls below the sound levels created
by the students.
Second, it is impossible to eliminate background
noise created by its occupants and instructional equipment, in order
to reduce the background noise enough to ensure that ALL children
throughout the room are achieving a Signal to Noise Ratio of +15
decibels. This was proven in the LAUSD study previously discussed.
For example, the typical conversational level of a teacher’s
voice is 65 dBA, which means that the background noise can theoretically
be no more than 50 dBA to achieve a SNR of +15
dBA. However, this assumes that all students are
within a normal conversational distance to the teacher, so that
sound is not decreasing over distance. (Remember that sound decreases
6 dBA for every doubling of distance.) We know that a classroom
set-up allowing all students to be within 2-3 feet of the teacher
is impossible. Children are seated throughout the classroom, staggered
over the distance of the room, more than conversational distance
from the teacher. Beyond 8 feet from the teacher, the teacher’s
voice will be heard at less than 47 decibels, which produces an
SNR of negative 3 dBA (47dBA minus 50dBA), not enough for students
to hear and fully understand what is being spoken.
Therefore, the only feasible way to overcome this
barrier is to bring the teacher’s voice at 65 decibels, closer
to each student, including those in the back row. This is the rationale
behind the classroom sound enhancement system, which creates a front-row
seat for every child in the classroom. The classroom sound
enhancement system works by picking up and amplifying the teacher’s
voice (8-10 decibels) from a wireless microphone and distributing
it through four to six ceiling speakers strategically placed throughout
the classroom. With students sitting no more than 10 feet
from one of the ceiling speakers, this allows every student the
acoustical advantage of sitting in the front row and ensures that
ALL students achieve a signal to noise ratio of +15 decibels, at
a minimal cost of $1000 per classroom.
The initial generation of sound enhancement systems employed a
FM radio signal for the wireless microphone. This is still widely
utilized and, for some types of situations, this is the system of
choice. However, the dependency on limit FM frequencies greatly
restricted widespread use of this technology in more urban environments.
Beginning in the 1990’s, Infra-Red (IR) classroom enhancement
systems were introduced. IR has the advantage of precluding interference
between classrooms, eliminating static, and no longer restricting
the number of classrooms due to restrictions in the number of frequencies.
When people hear that a sound enhancement system
raises the teacher’s voice 8 to 10 decibels, people fear the
“blasting” of the teacher’s voice. The common
misperception is that sound enhancement systems are small public
address systems which will produce an excessively loud teacher’s
voice causing sound bleed-over into the adjacent classrooms. Those
who believe this, either do not understand how a quality
sound systems works or they have had the misfortune of using an
inferior audio product that was either not installed correctly or
not used correctly.
If a quality system is correctly installed, the
primary benefit is in the even distribution of the teacher’s
voice, not the amplification of the teacher’s voice.
In fact, sound enhancement systems allow the teacher to use a conversational
tone, because he/she doesn’t have to be concerned with projecting
their voice to the back of the room. A teacher can actually speak
in a softer more nurturing voice, which is more conducive to learning.
Therefore, the 8-10 decibel increase is insignificant and does not
cause any sound bleed-over. Instead, the voice is more clear, crisp
and understandable regardless of the physical position of teacher
and the student.
Classroom sound enhancement systems should not be identified with
the personal worn FM hearing systems. Personal worn FM systems are
assistive hearing devices used by hearing impaired children. They
benefit only the single child using the personal device, by picking
up the teacher’s voice and directing it into the ear of the
hearing impaired child. They filter out the background noise. This
is helpful and a necessary learning aid for the hearing impaired
child, but it does not benefit the other children in the class.
It also only amplifies the teacher’s voice, not the voices
of the other students in the room. So, unlike the classroom sound
enhancement system that offers a hand-held microphone for the children
to use, the hearing impaired child cannot hear or learn from the
other students talking in the room. Sound enhancement systems used
in addition to personal FM assistive technology allows the hearing
impaired child to hear other the students and the teacher, including
the hearing impaired child as part of the class discussion.