144 FONIX FP35 Hearing Aid Analyzer
5.5.4 Important Notes on DSL Testing
The DSL fitting method is slightly more complicated than the other fitting rules
available on the FP35 analyzer. For this reason, it is important to keep a few
things in mind when using DSL:
• DSLwasinitiallydevelopedforchildren.Forthisreason,itisimportant
to input the client’s age when generating a target for a child. If no age for
the client is set, the analyzer will assume that it is generating a target for
an adult. See Section 5.3.4 for instructions on how to generate a target.
• TheDSLWDRCtargetwillchangedependinguponthesourcelevelof
CRV 2. So, if you would like to see the DSL WDRC target for 80 dB SPL,
for example, set the amplitude of CRV 2 to 80 dB SPL. The DSL LIN target
will also adjust to the amplitude of CRV 2, but its adjustments will be lin-
ear.
• DSLdemandsaslightlydifferentspeechweightinginitsmeasurement
signals than the speech weighting we usually use. When fitting an adult,
DSL requires the adult long term average speech spectrum (A-LTASS)
weighting. When fitting a child, DSL requires the child long term aver-
age speech spectrum (C-LTASS). The FP35 will automatically use these
speech weightings unless specifically directed otherwise. See Section
2.5.2.1 for more details.
• WhenDSLLINorDSLWDRCisthefittingmethod,theFP35willput
three lines on the SPL Testing Screen, denoting the LTASS. Once a real-
ear measurement is taken, these lines will disappear. See Figure 5.5.4.
Figure 5.5.4—SPL Testing Screen with a DSL WDRC target and the LTASS speech banana.
