Table 7. Frequency of reported male change in voice across eight time points.

Q	Age (Y)	No change	Changes occasionally	Totally changed	Unsure	N (=100%)
2	9	94.3%	4.1%	<0.2%	1.5%	3321
3	10	92.8%	5.9%	0.2%	1.2%	3107
4	11	82.4%	14.1%	1.1%	2.4%	2902
5	12	51.7%	31.3%	12.9%	4.1%	2774
6	14	9.1%	34.9%	42.3%	13.6%	2256
7	15	11.2%	24.7%	50.2%	13.9%	2246
8	16	13.2%	15.7%	60.8%	10.3%	1916
9	17	22.1%	9.7%	57.7%	10.6%	1750

Q = questionnaire no.; Y = year of age; N = no. of individuals with data