*3.3.1. Purpose of the technique*

Sound-based interventions (SBIs) are a type of sensory-based intervention used by occupational therapists and some physical therapists with children diagnosed with ASD. SBIs originated from the work of Tomatis [33, 34], whose research on the ear and its connection to the nervous system led to his theory that one's "listening function" affects voice, language, motivation, coordination and learning abilities [35]. The theory that Tomatis postulated was that by listening to certain frequencies, the brain could retrain itself by creating new neural pathways, thereby compensating for dysfunctional brain structures or pathways. Tomatis's ideas led to the development of several SBIs, including the Tomatis Method®, Auditory Integration Training®, Therapeutic Listening®, Integrated Listening Systems® and The Listening Program®.

#### *3.3.2. Overview of the technique*

SBIs involve listening to psychoacoustically modified music, yet the manufacture of each SBI differs in the dosage, type of music used, how it is combined with other intervention techniques. In most cases therapists (occupational and some physical therapists) use SBIs as combined modality with other sensory-based treatment or to augment Ayres Sensory Integration Intervention.

#### *3.3.3. Review of the evidence*

Because the evidence supporting the use of SBIs with children with ASD is mixed, these techniques are non-reimbursable and should be considered experimental. To date, most research on SBIs has been focused on the Tomatis Method and Auditory Integration Training and has produced mixed empirical results [36, 37]. Some studies have suggested that these interventions may be effective for individuals with ASD, citing improvements in areas such as language, psychomotor skills, personal and social adjustment, non-verbal communication and adaptation to change [38, 39]. However, other research has found little to no significant improvement in individuals who received SBIs as compared to the control groups [40, 41]. Recent single case research indicated that some children with ASD using home-based SBIs demonstrated mild to moderate improvements in behavioral and sensory tolerance [42]. Other case studies observed a reduction in behaviors and scores related to auditory sensory over responsivity, as well as a reduced number and duration of self-stimulatory behaviors after using a SBI in conjunction with occupational therapy [43, 44].
