the fitting formula is setting the parameters for global tuning, and sets the prescription for target gains acording the input of the audiogramm and acoustic parameters.
Phonak Target support different fitting formulas
- APD / APD 2.0
- NAL-NL1
- NAL-NL2
- DSL v5a
APD is a proprietary fitting formula only available in Target for Phonak Hearing Aids
- Adaptive Phonak Digital (APD)
- APD were available for Marvel and earlier legacy devices
- APD 2.0 is the new fitting formula available for Paradise, Lumity.
You can switch between the formula in Target
Select → Fitting → Global tuning → Fitting Formula
See also Phonak Target Step-by-Step Guide
default in Target is APD , or APD 2.0 (depending on the selected heraing aids) , and this default setting also could be changed in Target settings
Then you can also choose between this fitting formulas
- DSL
- NAN-L1
- NAN-L2
This are the standard fitting formulas supported by most hearing aid manufacturers
NAL-NL1 & NAL-NL2 is a very common fitting formula for less severe hearing losses.
Most manufacturers have modified this standard fitting formula, and made it work better with their own technology.
Oticons proprietary fitting formula is VAC+ , e-Stat is Starkey fitting formula, ReSound using Audiogram+ fitting formula , and so does Signa, Philips, Widex have each his own proprietary fitting formulas
You can watch this course on fitting formulas on Audiology Online
Fitting Formulas: History, Principles and Clinical Applications