Adam Walker, Audiological Scientist

How do we hear?

Sound is actually vibration of air molecules, these air molecules are funnelled into our ear canal by our ‘external ear’ and they travel down the canal until they hit the eardrum.  This causes the eardrum to vibrate, which in turn causes the three little bones inside the ‘middle ear’ (ossicles) to vibrate.  The vibration of the ossicles is transmitted to the cochlear, which is in the ‘inner ear’.  It is the job of the cochlear to convert the vibration into a nerve impulse and it contains specialised ‘hair cells’ that perform this task.  The nerve impulse is then sent, via the auditory (hearing) nerve to the auditory cortex in the brain where we perceive the sound.

 

How do we test children’s hearing?

A child may be referred to an audiologist for an ‘age appropriate hearing test’, which means that we test their hearing using an assessment technique that is suitable for their age and level of development.  This involves playing sounds through a speaker or through headphones and teaching the child a game to assess their responses to the sounds.  The type of game will depend on the age and/or development of the child, and may involve a ‘response’ to a sound (e.g. putting a peg on a board for children aged 2 and upwards), or a ‘reaction’ to sound (e.g. turning to the sound for children under 2).  Different frequency sounds will be played and we will determine the quietest volume that the child can hear at each frequency. This gives us information as to how clearly they are able to access speech as well as identifying whether the hearing loss is conductive or sensorineural (see previous blog on what is hearing loss).