In the Christian tradition, the bells are tuned to the first five harmonics: the drone which is the bass octave, the fundamental (one octave above), the minor third, the fifth, and the nominal (an octave above the fundamental). The note heard when the bell rings is the nominal. To measure the grade and partial grades, an electronic spectrum analyzer is used at Cornille-Havard. However, it is the tuner’s skill and ear that will decide where and to what depth metal should be removed on the bell, until the desired sound is obtained.