Using headphones for your child depends on factors like volume, for how long
they are listening, and their ear canal size. When the child is young, his/her
ear canals are small, so the sound level which is low for older kids can be high
for your young child. The solution can be, let your child be old enough to
decide and tell you whether it is too loud or too low for him/her. In all given
conditions, do not let your child use headphones or earphones for longer
duration at one stroke. It is harmful.