Methods for assisting a technician in tuning a musical instrument exhibiting inharmonicity, such as a piano. The light emitting region includes a negatively doped layer, a positively doped layer, and an active p-n junction layer between the negatively doped layer and the positively doped layer. The liner is mounted in the boot and includes a bottom plate slidably mounted on the sole and a toe box provided on a front end of the bottom plate.