Google Answers Logo
View Question
Q: FM radio waves ( Answered,   2 Comments )
Subject: FM radio waves
Category: Health
Asked by: parabrarian-ga
List Price: $25.00
Posted: 24 Apr 2002 11:34 PDT
Expires: 01 May 2002 11:34 PDT
Question ID: 3390
Is there a health or environmental hazard associated with exposure to FM radio 
waves of the sort associated with transmission of sound to hearing impaired 
students via "assisted listening devices"?
Subject: Re: FM radio waves
Answered By: penguin-ga on 24 Apr 2002 17:02 PDT
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 

“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)

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 

“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.

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 

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.“

Additional Website that may interest you: 

An Overview of Hearing Assistance Technology By David Baquis. California State 

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!

Subject: Re: FM radio waves
From: oscar-ga on 24 Apr 2002 19:58 PDT
It's and audio issue, unlike a mobile phone issue, the headset is a
passive reciever...based on current knowledge the worst you can expect
is 'hearing damage' free lunch eh?

rf damage link
Subject: Re: FM radio waves
From: mvguy-ga on 25 Apr 2002 08:59 PDT
It should be pointed out that the FM radio waves produced by these
units are quite low in power and are just like the FM radio waves that
are passing through your body right now (unless you're in a cave or a
building with a metallic shell).  Think of the hundreds of RF
broadcasts -- radio, TV, ambulances, police, CBs, ham radios,
satellites, wireless phones, and on and on -- you could receive right
now if you had the proper equipment.  Those are all part of your
current environment; adding another low-power broadcast to this mix
just isn't going to make that much difference.  Also, while I don't
think there's any real reason to be concerned about cell phones, it
also should be pointed out that these ALDs operate at frequencies
about 72 or 216 MHz, almost the same as VHF TV stations, not at the
near-microwave frequencies used by some cell phones, so the signals
are absorbed much, much less by biological material.  The radiation
levels are so low there just isn't much cause for concern.

Here are a couple pages of interest for you:

Important Disclaimer: Answers and comments provided on Google Answers are general information, and are not intended to substitute for informed professional medical, psychiatric, psychological, tax, legal, investment, accounting, or other professional advice. Google does not endorse, and expressly disclaims liability for any product, manufacturer, distributor, service or service provider mentioned or any opinion expressed in answers or comments. Please read carefully the Google Answers Terms of Service.

If you feel that you have found inappropriate content, please let us know by emailing us at with the question ID listed above. Thank you.
Search Google Answers for
Google Answers  

Google Home - Answers FAQ - Terms of Service - Privacy Policy