Audioscan Verifit - Manual (Page 82)

Verifit ® User's Guide Version 3.12  May 2015
ANSI S3.46(2013) RECD
The ANSI S3.46(2013) Real Ear standard advises RECD measurement protocols that make the RECD a property
of the ear itself, and independent of transducer or acoustic coupling. To achieve this accuracy certain conditions
must be met in both RECD measurement and Test-box Speechmap coupling.
As earmold tubing effects are dependent on coupled sound source, the ANSI protocol accounts for these by
making the earmold part of the Speechmap testing in the test box. BTE hearing aids are coupled to the HA-1
coupler through the client’s personal earmold.
For similar reasons, the on-ear RECD measurement is performed with a foam eartip, rather than the earmold.
This minimizes the error that arises from unknown lengths of tubing added to the RECD transducer. These
tubing effects are now more correctly being accounted for during the simulation on the coupler.
The ANSI RECD protocol can pose certain challenges in clinical implementation so alternate methods of RECD
measurement are possible. Test-box Speechmap allows the selection of coupling for BTE instruments (HA-1 or
HA-2) so the more traditional HA-2 (BTE) coupler can be utilized.
RECD protocols
A measured RECD is used both for simulation in the coupler (Test-box Speechmap) and for correcting HL
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