Frequently Asked Questions
How can a school district justify paying for this technology when some schools are in need of plumbing, roof, and window repairs?
The two cannot be compared, they are equally important. It would be like
deciding whether to purchase the text books or fix the leaky roof. If the
roof gets fixed, but the students don't have any books to learn from, the
school does not serve its purpose.
Sound enhancement systems are a valuable necessary educational tool not a
facility improvement and hearing is not a luxury. Unlike money that is spent
on facility renovations and repairs, this is an investment that has a
significant opportunity for a financial return in the form of savings in
special education reductions and reduced substitute pay for absent teachers.
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What about the teacher who has a loud voice? Does that teacher need a sound enhanced classroom?
Absolutely yes! There are a few flaws (some technical) with the loud voice
theory. First our voices are not meant to be projected loudly for seven
hours a day, five days a week. This is why teachers are 32 times more likely
to suffer vocal problems than any other occupation; not to mention just
exhaustion, fatigue, and burn-out. Secondly, the energy of speech is carried
90% by the low frequencies yet only 10% of the intelligibility of speech
resides there. Intelligibility is carried by the weak high frequency sounds.
Thus a loud voice powers the vowels, but obscures the consonants. It is
counterproductive. Third, even a loud voice falls by 6dB for every doubling
of distance and given the current acoustical conditions the backrow still
loses 45% of speech intelligibility.
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Children in our school/district are achieving and scoring high in the standardized tests. Do we need this?
Yes. A study done in Colorado on children who had previously performed in
the 8th and 9th stanines increased their test scores by 3.64% after using
sound enhancement systems. This is statistically significant given the fact
that they were already "high-achievers" and did not have a lot of room for
test score improvement. It proves that even those who appear to be
achieving, may not be achieving their full potential because they too are
either not hearing ALL of the information and/or are using up excess energy
on listening that could be used for additional learning.
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Are the hand held microphones needed?
Yes, they are highly recommended. Research proves they encourage
student participation, sharing, and allows ALL of the
students to hear each other; thus engaging in passive learning.
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Do sound enhancement systems work in an open classroom?
Yes. Enhancement of the speech signal is highly desirable since the
speech-to-noise ratios are often poorer than closed classrooms, for two
reasons: The background noise levels are predictably higher, and the
teachers often use softer than average voice levels in order to reduce
interference with the teachers in adjacent classrooms. However, it is more
challenging in that placement of the speakers is critical and teachers may
need to coordinate schedules and alternate use of the system to avoid
interference. If the volume is properly set and regulated, it is feasible.
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Aren't the ANSI standards sufficient for establishing good acoustics?
Absolutely not. The ANSI (American National Standards Institute)
Standards regarding classroom acoustics completely ignore critical factors
contributing to poor SNRs (Signal-to-Noise Ratio) which negatively affects
every child's ability to hear in almost every "real world" classroom.
See the Poor Acoustics page for more details on SNR.
ANSI Standard Scope of Practice
1.1.2 acoustical performance criteria are
specified in this standard by limits on maximum one-hour a-weighted and
c-weighted background noise levels and limits on maximum reverberation
times. An objective of these performance criteria is to achieve a level of
speech that is sufficiently high relative to the background noise level for
listeners throughout the classroom or learning space. However, a requirement
for the relative difference between speech levels and levels of background
noise, usually referred to as the signal-to-noise ratio, is not within the
scope of this standard.
1.1.4 this standard does not apply to noise
generated within a classroom by its occupants. Occupant- generated noise
sources include voices and the sounds of classroom activities such as the
moving of chairs. Furthermore, this standard does not apply to the noise
from portable or permanent built-in equipment used during the course of
instruction, such as audiovisual equipment and computers. However, the
background noise generated by occupants and instructional equipment can
seriously degrade communication or speech intelligibility in learning
Why does ANSI exclude SNR from the scope of its standards?
- Even the best acoustical environment cannot correct the
problem of the teacher's voice dropping over distance.
The signal (teacher's voice) drops 6 decibels for every doubling
of distance. See diagram
- Acoustical modifications are also unable to address the level of
background noise generated by students, electronics, and other instructional
equipment in every "real world" classroom which is why their
standards must be based on an UNOCCUPIED classroom.
- ONLY a SES with speakers evenly distributing the sound can ensure that ALL
children in ALL areas of the classroom will hear the teacher's voice at
the recommended SNR of +15 decibels.
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Does a teacher have to wear two microphones if there is a student in the class using a personal FM system?
No. Teachers do NOT need to wear a second microphone in these instances. Teachers simply wear the
microphone for the classroom SES and the transmitter/microphone for the personal
system is connected to the classroom SES receiver. Many classroom SES models are able to interface
with ANY of the personal FM systems on the market, but be sure to confirm this with vendors if
such an option is important for your implementation. This may be important if existing service contracts
for personal FM systems need to be honored. There is also an added benefit for students
using personal FM systems in an SES equipped classroom. These students currently
"miss out" on passive learning that takes places from discussions/contributions
of other students in the classroom and from sound generated from other media
sources in the room. A personal system alone only allows the hard of hearing child to hear
the teacher. Most quality classroom sound enhancement systems include a
handheld student pass-around microphone that allows the hard of hearing child to hear the
other students and multimedia equipment if that too is connected to the SES.
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Are sound systems only needed at the elementary level?
No. Good acoustics are important at every level
of education in order to maximize auditory learning. While older children
may have a more developed auditory neurological network and be less
prone to ear infections, there are other considerations that warrant
improved classroom acoustics through use of sound enhancement systems.
Middle school, high school, and college students are required to rely
more on their own note taking abilities and less on “handouts” from
teachers. Therefore, they need to be able to clearly hear and understand
what their teacher is saying in order to properly learn and record
that information. Also, older students are more prone to hearing loss
generated from overexposure to high levels of noise. Approximately
3% of children in grades 1-3 have a high pitch hearing loss which is
attributable to damage from excess noise. In comparison, 30%
of college freshman and 60.7% of college sophomores have significant
hearing losses. Students with noise induced hearing loss are at high
risk form speech intelligibility problems in typical noisy and reverberant
classrooms. (Lipscomb, D.M., “The Increase in
Prevalence of High Frequency Hearing Impairment Among college Students,” Audiology,
1972, Vol. 11, pp. 231-237.)
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