The present research aimed at demonstrating whether the so-called “Tomatis® effect”, the reeducation of the auditory system, relies on an actual modification of sound encoding along the auditory pathway, from brainstem to cerebral cortex. On the one hand, this was evaluated by comparing the auditory evoked potentials of the electroencephalogram (EEG) – brain activity related to the encoding of sound features – before and after the treatment. On the other hand, the “Tomatis® effect” was compared to the effect of the same music in its natural state. In this pilot phase, a “Tomatis Group” (TG) and a “Control Group” (CG) of six healthy participants each were involved in the study. Participants of the TG received 13 two-hour listening sessions following a TOMATIS® listening program and participants in the CG received 13 two-hour listening sessions of the same musical pieces as used in the TOMATIS® program presented through the same TOMATIS® device, but not processed with the Tomatis® Gating system and with the bone conductor output switched off. In the EEG sessions the complex Auditory Brainstem Response (cABR) or Frequency Following Response (FFR) and the mismatch negativity (MMN) were recorded. The FFR is the biological signature of sound encoding at the level of the inferior colliculus in the ascending auditory pathway along the brainstem, which has been shown to track plastic changes in the auditory brainstem during both short-term and long-term learning. MMN is the cortical auditory evoked potential that reflects the violation of an acoustic regularity encoded in the auditory cortex.
