The boy's time in the choir is a very precious time, determined at one end by a mix of natural potential and aptitude and at the other by their changing voices and the move on to senior schools.
One is used to hearing about voices breaking, but the more acceptable term these days is of changing. This from Wikipedia:
Under the influence of androgens, the voice box, or larynx, grows in both sexes. This growth is far more prominent in boys, causing the male voice to drop and deepen, sometimes abruptly but rarely "over night," about one octave, because the longer and thicker vocal folds have a lower fundamental frequency. Before puberty, the larynx of boys and girls is about equally small. Occasionally, voice change is accompanied by unsteadiness of vocalization in the early stages of untrained voices. Most of the voice change happens during stage 3-4 of male puberty around the time of peak growth. Full adult pitch is attained at an average age of 15 years. It usually precedes the development of significant facial hair by several months to years.
Since September we've seen three of the current year eights become 'non singers' (they continue to board during the week, but can take full weekend leave) and one more whose voice changed at the end of year six. This leaves just four year eights in full voice and going on the past years, it wouldn't surprise if we've just left with one or two come July.
Just this week one of the year seven boys saw (heard?) his voice change; in fact it happened over just a few days according to Tom. I sat next to his Father at Sunday's Evensong, who was typically pragmatic about it "One door closes, another door opens", but obviously sad for the boy who has been a stalwart when it comes to the tricky or high octave solos. This boy already has a place at Eton.
We also saw one of the year five boys need to rest his voice for 8-10 weeks, apparently due to nodules on his vocal cords. This from Wikipedia:
The nodules appear as symmetrical swellings on both sides of the vocal cords. The cause of these formations are usually strenuous or abusive voice practices such as yelling and coughing. Persons who are often susceptible are those who use their voice constantly in a loud environment. Examples include teachers, cheerleaders, politicians, actors, preachers, singers, and military drill instructors.
Precious time, precious ability.
More links:
The Male changing voice: http://www.leedberg.com/voice/pages/male.html
The different ways boys voices change: http://www.cambiatapress.com/CVMIA/differingways.html
A 'gap' in boy's changing voice: http://www.choralnet.org/view/281969
