In our research on deaf signing children, most of the work is conducted in a swedish context, where we adopt a bio-psychological approach. From a medical point of view, it might be easier to determine the level of hearing loss following an established nomenclature: for example, mild, moderate, moderate severe, severe, and profound. Based on a medical definition of disabling hearing loss, estimated that almost 2% of all the children in the world, corresponding to more than 30 million individuals, are affected.