It is probably hard to generalize the manufacturer formulas. They may all take a different approach. When I compare the SmartFit Power to NAL-NL2 there are some obvious differences. The NAL-NL2 is smoothed out. So there are areas where it under corrects compared to SmartFit, and other areas where it over corrects. SmartFit follows the hearing loss much more closely. And in general the NAL-NL2 boosts the quiet sounds more and the loud sounds less. In other words more compression.