With an audiometer (installed on a laptop) the hearing profiles of the right and left ear are determined. Those curves can be shown in an audiogram (fig. 1). Also the hand, eye, foot and ear dominance is determined. This can show us how laterality* in the body works out. In addition a Dichotic Listening Test gives us an impression how sound processing by the left and right ear takes place.
With the information of the audiogram a specially recorded music CD is put together. The program involves listening to this CD 10 – 15 minutes approximately 9 – 16 months, depending on progress. In this way frequencies are stimulated which deviate from the optimum curve (fig. 1).
Regular reviews (8 – 12 weeks) are carried out during the therapy period when hearing is retested and new CDs are made according to the individual need. During the stimulation period the children should not listen to music by earplugs or headphones. This can influence negatively the therapy. CDs can be listened by disc man, CD player, stereo set, etc. The headphones must be of good quality (without extra stimulation of for example the lower frequencies). The AKG-K77 is advised for Johansen-IAS.
CDs are specially recorded for the treated child / adolescent / adult. The CD only helps persons where it is meant for. When someone else listens to it this can cause damage or result in a sensitive hearing.
Therapy ends when the optimum curve is approached as near as possible. A last CD will be made to take care of the stability of the changes. It is very important that, after following the therapy, both ears are not delivered to extreme situations. Loud music via earplugs / headphones, standing near loudspeakers for example in disco’s, using very noisy tools, etc. It is important that both ears are “treated” well.
*Laterality is a stage in the neuro-motoric development in where the left or right hemisphere determines dominance. Before the age of about 6 years the child uses both hands and feet equal. Movements are each others image. The child doesn’t have consciousness of left or right. After the age of 6 lateralisation takes place. There is a developing of the coordination between both hands with a certain “allocation”; one hand carries out, the other hand assists. The dominant hand / foot takes over the proceedings more and more. After the lateralisation stage the right or left dominance is clear. However period and time of lateralisation are different in every individual. A late lateralisation can cause learning problems, because the feeling and understanding of left and right are very important for the reading, writing and arithmetic process.