Transcript (Baum Rev2) TIA FCC OET Meeting_June 4, 2009_ppt.ppt

Review of the
Development of TIA-1083
Consumer Complaints
In 2004, telephone manufacturers began to receive
customer complaints regarding hearing aid interference
problems with digital cordless telephones.
Specifically consumers were hearing a buzz noise when
using digital cordless telephones with hearing aids and
cochlear implants when set to T-Coil mode.
There were no reports of the buzz noise from analog
cordless telephones.
Industry Response
At the August 2004 meeting of TIA Subcommittee
TR41.3 a Gallaudet University presentation on the
subject was discussed along with possible causes for
the reported interference.
The consensus belief was that, due to the low RF
power levels used by cordless phones, the source of
the reported interference was probably magnetic.
Further work towards confirming this belief and
developing a testing method to characterize the
magnetic interference was conducted during the
remainder of 2004 and first half of 2005.
Industry Response
•
First, the complaint phones were tested for compliance
with the FCC Part 68.316 HAC regulations. The test
results confirmed that all of the phones were compliant.
•
Next, the complaint phones were tested with hearing
aids obtained from and programmed by Gallaudet
University. This testing confirmed that digital spread
spectrum cordless telephones were indeed causing
interference to hearing aids. (This testing also
confirmed that analog cordless telephones did not
cause interference.)
Why was this happening?
Analysis of the noise characteristics indicated that the
source of the noise was the Time Division Duplexing
(TDD) employed by the Digital Spread Spectrum (DSS)
cordless phones to enable them to transmit and receive
on the same frequency.
This turning on and off of the transmitter at a very rapid
rate resulted in large changes in battery current which
in turn caused large changes in the magnetic field
produced by the wiring in the handset.
This magnetic pulsing was being picked up by the
T-Coil in the hearing aid and heard as a loud buzzing
noise by the wearer.
HLAA Studies
2005 HLAA National Convention
Study conducted by Linda Kozma-Spytek of the
Rehabilitation Engineering and Research Center
(RERC) on Telecommunications Access and the
Technology Access Program at Gallaudet
University.
Volunteers from among the HLAA Convention
attendees tested a group of phones and rated their
performance.
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–
–
–
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Loudness
Percent Words Understood
Interference
Usability
“Would you buy a phone with this level of
interference?”
HLAA Studies
2006 HLAA National Convention
Study conducted by Gallaudet University, Etymotic
Research and Motorola.
Volunteers from among the HLAA attendees
participated in this study and helped to answer the
question:
“How much noise is too much noise?”
TIA Completes Development
of New Standard
Results from the two HLAA Studies were compared
with lab measurements by TIA member companies.
Performance Requirements were Established
Compliant phones were tested by wearers of hearing
aids and cochlear implants with good results.
ANSI/TIA-1083 “Handset Magnetic Measurement
Procedures and Performance Requirements” was
published in March 2007.
Official “TIA-1083” logo was developed and licensed
by TIA to manufacturers for display on the packaging
of compliant products.
Official TIA-1083 Logo
Compatible with
Hearing Aid T-Coil
T
TIA-1083
Compliant products with this logo are currently
widely available in the market.