Here ya go, Steve. This isn't Hsu's web site, but it's the same thing.
Using 40Hz. as an example, and assuming you're calibrating to 75db (substitute 85db if your using Avia), and assuming I remember this correctly, when your meter reads 75db at 40Hz, you're actually getting only 72.5db. So, you want to increase the volume until the meter reads 77.5db. Then you've actually got your 75db.
In other words, add or subtract the amounts in the chart to the initial reading you get on the meter, to make it correct.
