Hi Parabrarian!
Volume control is one health risk involved with the FM radio waves as an
assisted learning device. Interference or lacks of privacy are two
environmental issues. These issues are improving as the technology for
assistive learning devices improve.
You may be happy to know, “Exposure to radio waves causes no major health
problems and is not regulated.”
The Electromagnetic Spectrum
http://library.thinkquest.org/27930/spectrum.htm
“The ability of RF (radio frequency) energy to affect living things depends on
the strength, or intensity. Over the years, scientific studies have indicated
that below a certain intensity level, RF energy does not effect living
organisms. Several scientific and technical organizations have developed
exposure guidelines or standards, which recommend limits on exposure to ensure
that no adverse effects occur. At levels above the recommended exposure limits,
exposure to RF fields can increase the temperature of biological tissues. Below
these limits, however, even prolonged exposure to RF energy has not been shown
to affect, or cause any changes, in living organisms.”
IBM Wireless Local Area Networks (LAN)
http://www.pc.ibm.com/ww/healthycomputing/lan.html
However, there could be some health issues involving the FM systems due to
negligence. “First, as shown by Freeman, Sinclair and Riggs (1980) in
laboratory settings and by Bess, Sinclair and Riggs (1984) in a field
investigation, certain FM-wireless devices are capable of producing maximum
sound pressure levels exceeding 140 decibels. The Food and Drug Administration
has determined that consumers must be warned of potential risk to residual
hearing if an auditory amplification device exceeds 132 dB sound pressure level
of output.
(Let it be known that the threshold for pain is 130 dB.)
“Preventing Hearing Damage”. Music Injury.com
http://www.music-injury.com/html/prevent_loss.html
“Second, it should also be noted that many of the commercially available FM-
wireless devices have trimmer screws (settings on the receiver) that alter the
performance characteristics of the systems. The trim screws are intended by the
manufacturers to be set by the audiologist to meet the listening needs of
specific end-users. They are not intended to be adjusted by consumers or non-
clinicians. “
“National Task Force on Quality of Services in the Postsecondary Education of
Deaf and Hard of Hearing Students” by Ruth Warick, Catherine Clark, Jesse
Dancer, Stephen Sinclair.(1997). Rochester Institute of Technology.
http://www.rit.edu/~netac/publication/taskforce/device/device6.html
The Access Board mentions some important environmental issues. Since you are
interested in the effects on students, this may or may not affect you. “The FM
signals do not stay contained within the four walls of an enclosure. If privacy
is a consideration, then an FM system is not appropriate for that facility. The
second potential problem is the obverse of the first: radio signals originating
outside of the facility can enter the facility and interfere with reception.
One cannot prevent occasional interference, as when an emergency vehicle in the
area transmits on the same frequency used in the venue. However, persistent
interference can usually be overcome by selecting alternate frequencies within
the permitted bands. On the up-side, it is relatively easy with an FM system to
ensure adequate signal strength at all seat locations, even in the largest
venues.”
The Access Board. “ASSISTIVE LISTENING SYSTEMS BULLETIN #9C: FOR PROVIDERS”
http://www.access-board.gov/publications/9-als/bulletin-c.txt
Comments of the Alexander Graham Bell Association for the Deaf and Hard of
Hearing reveal that this technology is improving. “People who use devices that
operate in the 72-76 MHz band shows that the interference experienced in many
parts of the country can cause their performance to be inadequate. For this
reason many parents and school systems have invested in new equipment that
utilizes the 216-217 MHz band... Our members also noted that in the 216-217 MHz
band, this interference has heretofore been nonexistent. We ask the Commission
to join us in the conclusion that 216-217 MHz is a safe harbor for the users of
assistive listening devices.“
http://www.agbell.org/advocacy/216fcc.pdf
Additional Website that may interest you:
An Overview of Hearing Assistance Technology By David Baquis. California State
University-Northridge
http://www.csun.edu/cod/conf2000/proceedings/0099Baquis.html
Search Terms Used:
"Food and Drug Administration" FM listening device risk
FM Waves audio assistance interference
google audiology
FM ALD specifications
"76 MHz" danger or safe
I hope this helps your understanding of this incredibly helpful technology!
Penguin |
