A normal child’s sense of hearing is formed in this way: the auricle collects sound from the outside world, which is conducted inward along the external auditory canal and transformed into mechanical vibrations at the eardrum. These mechanical vibrations travel along the auditory ossicles and deeper into the inner ear. The inner ear converts the mechanical vibrations into electrical nerve signals that travel along the auditory nerve to the auditory center (brain), ultimately forming the sense of hearing. This process is what we call “air conduction” during an examination. If there is a problem in any part of this process, hearing loss will occur, i.e. deafness. Deafness in general can be divided into three main categories: conductive deafness if there is a problem with the outer ear canal and the middle ear, resulting in sound not being transmitted to the inner ear (children with small ears are basically in this category); sensorineural deafness if there is a problem with the inner ear, resulting in mechanical vibrations not being converted into bioelectrical signals; and neurological deafness if there is a problem with the auditory nerve or the center of the brain. One concept that you need to keep in mind is that children with small ears are basically conductively deaf, which means that sound does not get through. In this case, sound passes directly through the skin and skull and is converted into vibrations that are transmitted directly to the inner ear, where hearing is formed in the auditory center. This conduction pathway is called “bone conduction”. The bone conduction hearing aids I will talk about later on utilize this conduction pathway. According to the World Health Organization deafness classification standards: normal hearing is 25 decibels and below; mild deafness is 26 to 40 decibels; moderate deafness is 41 to 55 decibels; moderate deafness is 56 to 70 decibels; severe deafness is 71 to 90 decibels. As you can see here, the higher the decibel count on the hearing test, the worse the child’s hearing. So, how many decibels is it usually for conductive deafness in a child with small ears? If parents have taken their child for an ABR or pure tone audiometry, the child’s results, usually, are 60-80 decibels. Against the criteria above, a small-eared baby presents with moderate to severe or profound conductive deafness. So what is the concept of 60-80 decibels of conductive deafness? Parents can put their pinky or ring finger into the outer ear canal and tightly block the outer ear canal, and that is when a conductive deafness of about 40 decibels occurs. Parents reading this may want to give it a try and experience what 40 decibels of conductive deafness really feels like. It is obvious that you can’t hear the outside world, but if you listen carefully, you can still hear a little bit of it. Secondly, you hear a “rumbling” noise, which is the noise made by the blood flowing through the veins in the body, and if you listen carefully, you even hear the heartbeat. In children with atresia, the hearing loss is more severe, with a conductive deafness of 60-80 decibels. So what does conductive deafness look like at around 60 decibels? When the landline phone rings at home, imagine how far you need to walk to not hear anything at all. When you can’t hear the landline phone ringing, it’s the equivalent of a child standing by the phone. To summarize: external sounds are clearly inaudible, and self-noise is clearly heard. One final point from the perspective of temporal bone anatomy is why children with small ears develop conductive deafness. Babies with small ears either have no external auditory canal or have a malformation of the auditory ossicle chain. Both of these possibilities make it impossible for sound waves from the outside world to travel to the inner ear, and eventually conductive deafness occurs.