Informal tests do not give an accurate measure about the exact degree of hearing loss. Milder degrees of hearing loss may be missed out on such testing. Also, these tests do not check the hearing in each ear individually. At times, the child may be responding to visual movement in his / her field of vision (which you may not realize), or to the vibration that accompanies the sound and this may be mistaken for the child’s response to sound. It is therefore best that you go to a person well-trained in testing a child’s hearing at the slightest suspicion of hearing loss.