Audioscan Verifit - Manual (Page 92)

Verifit ® User's Guide Version 3.12  May 2015
3. There is no provision to input the number of compression channels. This may be useful when the signal used
for verification is not the signal for which the targets were developed. It is irrelevant when using real-speech
signals to match speech targets and when using narrow-band signals to match narrow-band maximum output
targets.
4. The term Uncomfortable Level (UCL) is used rather than Upper Limit of Comfort (ULC) in referring to the
ear canal SPL that should never be exceeded.
5. Broadband output limiting targets are not provided.
DSL 5.0 changes
The Audioscan version of DSL 5.0 includes provision for bone conduction and ABR threshold, binaural targets,
targets for speech levels from 50 to 75 dB SPL, new targets for children, targets for adults and new RECD
default values for children (1 month to 10 years) and adults. The UWO child’s spectrum has been removed and
an 'own voice' spectrum has been added. As a result of a re-analysis of published data, the vocal effort effects for
Soft and Average speech levels have been made the same. In addition, the target symbol has been elongated to
indicate that the fit-to target is a range, not a point.
The children’s LTASSa targets for 70 dB speech are lower than those in previous versions of DSL. These
differences are functions of the hearing loss and age (where average RECDs are used). Revisions made in
version 5.0a reduce these differences at 250 Hz and for more severe losses. The differences will be more
significant when the individual RECD values have not been measured for the child being fitted.
Audioscan assumes no responsibility for the validity of these changes; that responsibility rests with the National
Centre for Audiology.
NAL-NL1 in Speechmap
The NAL-NL1 procedure seeks to amplify speech such that all bands of speech are perceived with equal loudness
while maximizing speech intelligibility and ensuring that the wearer perceives speech to be no louder than that
which a normal hearing person would perceive. Although NAL-NL1 states its goals for speech, it derives
insertion gain targets assuming noise as a verification signal. Because it is more accurate to verify a non-linear
fitting using the signal for which the procedure was developed, Audioscan converts the NAL-NL1 insertion gain
targets to LTASS targets for amplified speech in the Speechmap environment, resulting in Speechmap/NAL-
NL1. The conversions use the same adult average RECD and REUG as used in DSL. The RESR targets are from
Hearing Aids (Dillon, Thieme Publishing, 2001, p274).
An insertion gain version is available by selecting [Insertion gain] from the on-ear measures test menu. The pink
noise stimulus should be used.
NAL-NL2 in Speechmap
Fitting targets, default age-related RECD and REUG are provided by a software library used under license from
Hearworks Pty Ltd. which is solely responsible for their derivation.
This revision of NAL-NL1 has many more input parameters and output target formats than its predecessor. In
implementing NAL-NL2, Audioscan has made the following simplifications and clarifications:
1. NAL-NL2 targets are provided as REAR targets in Speechmap. Insertion Gain targets are not provided.
2. There is no provision to select Insert earphones + earmold as the audiometric transducer since this
invalidates the audiometer calibration and correction for this error is problematic.
3. Input-output curve targets and compression threshold targets are not provided. Such steady-state parameters
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