If the brace is too high or too low, the bow will probably become noticeably louder. Somewhere between the two, the bow will become noticeably quieter. Somewhere within that sweet spot, is your correct brace. There are many ways to test and adjust the brace within that sweet spot for final tuning. One technique is to shoot through paper at about 8-feet and fine tune your brace higher or lower in small amounts to eliminate any left or right tears on the horizontal plane.
You'd do the same for the nocking point height to fine tune and eliminate any up or down tears on the vertical plane. This is most often used to make small final corrections to match point of impact between your hunting broadheads and target field points.
The above works well if your arrows fall somewhere in the middle of the bell curve for correct overall spine as needed for you and your bow. But, the above may not work so well if your arrows fall somwhere on the outer edges of the bell curve where they are too stiff or too weak.
Best