Biomedical Engineering Reference
In-Depth Information
Figure 6-9.
Example floor-style FM soundfield system (products not to scale). From
left to right: Phonak Inspiro microphone transmitter; Phonak DigiMaster receiver and
loudspeaker; and Phonak DymaMic microphone transmitter. the Inspiro is used by
the teacher or lecturer, whereas the DynaMic is a pass-around microphone used
by the class or meeting participants for comments and questions. the DigiMaster
loudspeaker stands several feet high (or can be wall mounted). Images courtesy
of Phonak.
personal FM systems, there are a variety
of ways in which a microphone/transmit-
ter can be used for education, communi-
cation, and entertainment. Disadvantages
include some potential radio frequency
interference by other non-FM systems,
interference from other FM systems on
the same or adjacent channels, compat-
ibility issues with other FM products,
coupling issues with public FM receiv-
ers, and the need to carry FM receivers
around. Nevertheless, the benefits of FM
often outweigh the disadvantages.
alert customers that they are available.
There are several places to purchase or
download these signs to post on walls,
windows, and digital or print communi-
cations. The logo for induction loop sys-
tems is based on the International Symbol
for Hearing Loss and has an ear with a
line drawn through it (to signify hearing
loss) (Figure 6-10). More information
about the logo can be found on the Center
for Hearing Loss Help (http://www.hear
inglosshelp.com) and the Hearing Loop
(http://www.hearing loop.org) websites.
Public Signage
From Fixed to Dynamic/
Adaptive FM
For public areas offering HAT for use,
signs should be posted with the Inter-
national Symbol for Hearing Loss to
With FM systems, it is possible to reach
SNRs of 20 dB or greater. When FM is
