Each bell caster designs their profiles to give their bells a particular sound. Even today, foundries can be contacted by customers looking for a specific tone colour. A bell produces a main sound and secondary sounds which constitute its tone. The electronic spectrum analyser can be used to check the tone’s accuracy. But it is the tuner, with their expertise and their ear, that will choose where and to what depth they should remove metal from the inside of the bell to tune it perfectly. A technique perfectly mastered at Cornille-Havard.