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Verifit

User's Guide Version 4.8

November 2016

thresholds. If None is selected, audiometric data is transformed to SPL up to 12.5kHz if possible. Where high
frequency data does not exist, audiometric data will be transformed as per DSL Adult.

HL Transducer:

Sound source is used to obtain the audiogram. Select from [Headphone, foam,

mold (DSL only), LS 0, LS 45, LS 90 (sound field) or ABR (DSL only). If Headphone is selected,
average adult real-ear to dial difference (REDD) is used to convert entered HL values to ear canal SPL. If
foam

is selected the appropriate real-ear to coupler difference (RECD) is used to convert entered HL

values to ear canal SPL values. If mold is selected, the audiometer is no longer calibrated and a
measurement protocol is provided for accurate conversion of entered HL values to ear canal SPL. If Measure
is not selected, entered HL values are converted to ear canal SPL as if a foam tip had been used to obtain the
audiogram. If LS 0, 45, or 90 is selected appropriate real-ear unaided gain (REUG) values @ 0, 45, and 90
degrees azimuth respectively, will be used to convert HL values to ear canal SPL values.

RECD:

Real-ear to coupler difference. Unless otherwise indicated, RECD is the difference between the SPL

in an occluded ear and the SPL in the HA-1 2cc coupler produced by the same high (acoustic) impedance
sound source with the same acoustic coupling. Because of standing waves in the 2cc coupler, it is not useful
above 8 kHz. The Verifit has adopted a 0.4cc coupler to extend the capabilities of Speechmap Test box to
the 1/3 octave band at 12.5 kHz. The term Wideband real-ear to coupler difference (WRECD) has been
coined to denote an RECD based on a 0.4cc coupler rather than the HA-1 coupler. The

WRECD

is the

difference between the SPL in an occluded ear and the SPL in the 0.4cc coupler produced by the same high
(acoustic) impedance sound source with the same acoustic coupling.

The WRECD is used to convert 0.4cc coupler SPL measured in the test box to estimated ear canal SPL. The
WRECD is used to convert entered HL data (thresholds and UCL's) to ear canal SPL when Foam is
selected as Transducer. Below 8 kHz, the Verifit converts between RECD and WRECD as necessary.

Except for Camfit targets, RECD choices are Average, Enter, or Measure.

If Average is selected and DSL child or NAL-NL2 is the target rule, age-appropriate average RECDs will be
applied. However, these target rules provide different average values which will result in differing SPL
thresholds. Average RECDs for frequencies above 6 kHz are set equal to the 6 kHz value for purposes of
converting HL thresholds and 0.4cc coupler SPL to ear canal SPL.

If Enter is selected, after threshold entry has been completed, a selection must be made between HA-2
RECD, HA-1 RECD and 0.4cc WRECD. Once a choice has been made, an 8 kHz RECD entry screen or a
12.5 kHz WRECD entry screen becomes available.

If Measure is selected, the Measure WRECD screen is provided after threshold entry is completed. See
WRECD measurement.

4. RECD Coupling:

Select from [Earmold, Foam tip]. Specifies the coupling between the RECD transducer

and ear.

Age:

Select from Adult, 6 – 10 years, 1 – 60 months. This changes the RECD applied if DSL Average or

NL2 Average has been selected when using these target rules.

ABR nHL to eHL:

Normalized HL to estimated HL conversion factors. Permitted only if [Transducer] =

ABR (nHL). Select from [Default, Enter]. If [Enter] is selected, an entry screen will be provided after
threshold data have been entered. Otherwise default factors will be used. These may be set to DSL values or
to values that you have entered in Setup. Note that, in some facilities, nHL is defined in such a way that it is
effectively eHL; in these cases, ABR (eHL) should be selected and no conversion factors will be applied. See
ABR nHL to eHL setup.

Binaural:

Select from [Yes, No]. Determines if fitting targets will be adjusted for binaural summation

effects.

REDD:

Real-ear-to-Dial Difference. [Average] (this cannot be changed). REDD values are similar for adults