Each fret on a guitar needs to be the same height or shorter than the preceding fret. Irregular frets will prevent the strings from vibrating properly and impede the instrument’s sound. High frets will cause lower notes to lose sustain, buzz or even choke out completely.
If your guitar is experiencing these symptoms, a fret rocker will be helpful to locate the high fret(s).
A fret rocker is a tool that allows you to compare the height of any three frets at a time. If at anytime the fret rocker is able to rock back and forth, like a teeter totter, the fret in the middle of the rocker is too high. If your guitar has a high fret, it is necessary for a reputable technician to service the instrument.