The Church Times reports,
Whereas, in the past, boys continued singing treble until they were 15 or 16, now musical directors and choir masters often find that boys’ voices are changing at 12 or 13.
A Danish study, carried out at Copenhagen University Hospital, has found that, over the past ten years, the voices of boys in a leading choir school have broken earlier and earlier. Researchers have linked this change to weight and diet, and an earlier start to puberty in both boys and girls.The Telegraph has more,At some schools, a scholarship is still honoured after a boy's voice breaks; at others it is downgraded, meaning parents have to pay more in fees.Meat heavy diets and improved prenatal diet of mothers have been attributed to earlier onset of puberty. In boys, however, obesity is associated with a delay in puberty.
Choristers usually start from the age of about eight, although at some cathedrals they are now recruited from the age of seven.