no inclusion since the opening of the centers (difficulties in recruiting staff which impact the functioning of the services)

The therapeutic management of Obstructive Sleep Apnoea Syndrome in children remains a debated subject, only otorhinolaryngology surgery (adenoidectomy) has been studied on a large scale. Pathophysiologically, increased pharyngeal collapsibility is a major endotype of the disease and the investigators have shown that this surgery can improve pharyngeal compliance. The development of approaches to treat pharyngeal hypotonia by maxillofacial rehabilitation supports the treatment of this endotype. A study in adults showed a benefit from playing the didgeridoo, a wind instrument, for 3 months, without pathophysiological explanation. The investigators hypothesise that playing this instrument improves pharyngeal compliance (re-education effect) in a similar way to the effect observed after otorhinolaryngology surgery.

This proof-of-concept study aims to demonstrate the effect of didgeridoo in children without syndromic pathology with a formal otorhinolaryngology surgical indication resulting from tonsillar hypertrophy (Brodsky grades III and IV) and symptomatology suggestive of Obstructive Sleep Apnoea Syndrome (Pediatric Sleep Questionnaire score ≥ 0.33). The investigators will take advantage of the long delay in performing the adenoidectomy (~6 months) in their university hospital to evaluate, before the scheduled surgery, the effect of the didgeridoo used for three months.

Randomised controlled trial, with minimisation criteria, single blind, bicentric.

The subjects will be divided into 2 groups, according to the strategy of care before the date of the scheduled surgery: 1. Abstention (routine care) 2. Didgeridoo rehabilitation.

The primary objective is to improve pharyngeal compliance measured non-invasively by acoustic pharyngometry in the didgeridoo arm compared to a no treatment arm.

The secondary objectives are to demonstrate the effect of the didgeridoo on clinical signs associated with Obstructive Sleep Apnoea Syndrome and on an indirect index of apnea-hypopnea during sleep.

Inclusion Criteria:

• Clear tonsillar hypertrophy (Brodsky grade III to IV), justifying surgery
• Pediatric Sleep Questionnaire ≥ 0.33
• Discontinuation of any prescribed medication for Obstructive Sleep Apnea Syndrome (anti-histamine and montelukast)
• Access to the Didgeridoo course
• Consent of the holders of parental authority and agreement of the child

Exclusion Criteria:

• Syndromic pathology
• Lack of affiliation to a social security scheme
• Holders of parental authority under guardianship or curatorship

The nurse performing the rhinopharyngometry measurements does not perform the compliance calculation (primary objective). The measurements from the acoustic pharyngometry are analysed (compliance calculation) by a doctor who does not know the child's randomisation arm. Thus, if the subjects have knowledge of their randomisation group, the assessment of the primary endpoint is blinded.