Year ≥ 2008
Time Enrolment
Age Pregnancy and birth Early life 0-3 years Childhood 3-12 years Teenage 13-19 years
Hearing problems P:SDV
S – self report
P – parent report
C – child report
T – teacher report
N – welfare nurse
O – observation
XM: Mother
XF/P: Father/partner
XC: Child
XS: Sibling
XG: Grandparent

SDV: Study Devised Variable