Johansen Sound Therapy or Auditory Discrimination Training (ADT) is the technique developed by a Danish headmaster, with a background in physics, specialising in learning difficulty. The premise behind this technique is to modify pre-recorded music according to the individual audiometric assessment. In other words, wherever the individual displays an over-sensitivity for specific frequencies the volume is reduced, wherever a reduced sensitivity then the volume is increased. This changing of volume being done at an individual frequency level. The music is also biased toward the dominant ear.
The treatment is based on Tomatis and Volf. Tomatis is frequently described as the father of sound therapy. He is a French Ear, Nose and Throat specialist who became aware of the importance of sensitivity to a range of sound frequencies and speech. He determined that an individual can only produce, with speech, those sounds that can be heard, this is known as the Tomatis Effect. Volf was working in a similar field and has become much better known for his work with the very low frequencies experienced as vibration.