Why do we use the mother’s voice?
The principle of auditory brain stimulation consists in reproducing the stages of hearing development in order to achieve a trouble-free integration of hearing and balance.
According to Prof. Tomatis, the fetus mostly perceives the high frequencies of the mother’s voice. So, first, we gradually filter out the low frequencies from the music. Prof. Tomatis' 'mother voice theory' was confirmed in a scientific study by Stanford University, titled,
Following this "acoustic return" to prenatal listening, the listening is repeated as in the womb. The music, or the mother's voice, only contains frequencies above 6000/8000 Hertz. This phase, during which the low frequencies are filtered out, often produces particular psychological responses in children. For example, the child may cling to the mother, or exhibit regressive behavior.
For the next phase, called “acoustic birth” by analogy with childbirth, the lower frequencies are gradually re-introduced, until the mother' s voice, or the music, is completely unfiltered, and therefore 'normal'. This process represents the transition from the filtered acoustic perception within the amniotic fluid to the sound transmission via air conduction after birth. All phases, up to the end of the acoustic birth, make up the passive phase of the therapy.
If the mother's voice is not available (for ex. in the event of adoption or if the mother has passed away), Mozart's music may be used as a non-emotional substitute. It is a perfect alternative, as Professor Tomatis describes in his book "Why Mozart", as it is particularly rich in high frequencies, which are essential for optimal effect. Moreover, the rhythm of Mozart's music is similar to the fetal heartbeat.
The new neural connections, formed during the passive phase, are put to work during the active phase. The child reads a story aloud into the microphone, repeats words or phrases, or sings. When learning a foreign language, the person is immersed in a "sound bath" in order to open ears and brain to the frequencies of the target language. In some cases, exercises with a speech therapist and motor exercises may be added.