Modulators were used throughout Britain from the mid-19th century onwards, primarily to help teach singing to children.The Englishman, the Reverend John Curwen (1816-1880), adapted his tonic sol-fa method of teaching vocal music from Sarah Glover (1785-1867), of Norwich, Norfolk. Curwen initially employed this technique to teach hymn singing to his Sunday School children, but such was its widespread success that by 1891, some two-and-a-half million people across Britain were being taught in this way. According to Idris Lewis in his book 'Cerddoriaeth yng Nghymru' (Music in Wales) (1945), the great revival of choral singing in Wales during the 1880s and 1890s would not have happened without the growth of sol-fa. For those unable to read musical notation, this system was a breakthrough, and amongst those individuals who promoted the method in Wales were John Roberts (Ieuan Gwyllt) and Eleazar Roberts. Weekly classes were organised to teach hymns, anthems and famous choral works, and in chapels, especially, singing standards were transformed.
Modulators were used throughout Britain from the mid-19th century onwards, primarily to help teach singing to children.