Introduction~Hearing loss, or deafness, is defined by the decrease in the perception of sounds. Conductive hearing loss is characterized by damage to the outer or middle ear. Its etiologies are congenital, malformative or acquired, sequelae of infectious or inflammatory processes (chronic otitis).~They cause a defect in the transmission of the sound towards the cochlea. Conductive hearing loss can be compensated by bone conduction hearing aids or middle ear implants.~Osteo-integrated bone conduction hearing aids (Baha, Ponto) have become the standard of care for patients with conductive hearing loss when an acoustic hearing aid can't be used.~These prostheses are percutaneous but for children the implantation of the osseointegrated abutment requires that the child has developed a sufficient bone thickness. In general, surgery is not possible before the age of 5 years. [Doshi et al. 2012].~They can be mounted on headband for testing [Haute Autorité de Santé, HAS 2008] or avoid surgery especially for very young children [e.g. Hol et al. 2005, Verhagen et al. 2008, Doshi et al. 2012, Doshi and McDermott 2015]. In this case the vibration of the bone is through the skin. But these systems on headband pose problems of maintenance and pressure on the skin.~Standard headband pre-tests are recommended by HAS [HAS 2014] and the bone anchored hearing aid is a gold standard for preoperative evaluation in children. It can be used to predict the potential benefit of the implanted system [Doshi et al. 2012]. Several transcutaneous systems are developed today [Reinfelt 2015, Doshi et al. 2012, Doshi and McDermott 2015] but they also require surgery and have an age limit before implantation.~MED-EL company has developed a new bone conduction system, ADHEAR, that does not require surgery and that transmits the sound by bone vibration through the skin. This system has the advantage of not applying pressure on the skin and has no age limit.~Objective of the study:~The objective of the study is to compare the new ADHEAR bone conduction hearing aid for children with conductive hearing loss to the commonly used reference system, the osteointegrated bone conduction prosthesis.~Comparator:~The comparator is the same in all the centers and will be the PONTO 3 SUPER POWER mounted on softband.~Hypotheses~The hypotheses are that patients with the ADHEAR bone conduction hearing aid:~do not have a mean tonal gain lower than that obtained with a PONTO 3 SUPERPOWER mounted on a softband.~have a gain in comfort compared to a PONTO 3 SUPERPOWER mounted on a sofband~Main objectives~The first main objective is to evaluate the non-inferiority of the ADHEAR system compared to the PONTO 3 SUPERPOWER softband system in terms of average tonal gain.~The second main objective of the study is to evaluate the superiority of the ADHEAR system compared to the PONTO 3 SUPERPOWER softband system in terms of comfort.~Secondary objectives~Evaluate skin reactions with ADHEAR and PONTO 3 SUPER POWER on softband.~Evaluate and compare perception in silence and noise with ADHEAR and PONTO 3 SUPER POWER on softband.~Evaluate and compare the subjective auditory perception with ADHEAR and PONTO 3 SUPER POWER on softband.~To evaluate the satisfaction and use of ADHEAR.~Plan of study~It is a prospective open multicenter randomized crossover study: measures will be done on the patient at the inclusion then by randomisation a first system (ADHEAR or PONTO 3 SUPER POWER on softband) will be fit to the patient and he will take it at home for 15 days. Afterwards, the patient will come back to the clinical center and measurements will be done with the first system. Then the patient will be fitted with the second system (PONTO 3 SUPER POWER on softband or ADHEAR) and will take it at home for 15 days. Afterwards, the patient will come back to the clinical center and measurements will be done with the second system.
Main objectives~The first main objective is to evaluate the non-inferiority of the ADHEAR system compared to the PONTO 3 SUPERPOWER softband system in terms of average tonal gain.~The second main objective of the study is to evaluate the superiority of the ADHEAR system compared to the PONTO 3 SUPERPOWER softband system in terms of comfort.~Secondary objectives~Evaluate skin reactions with ADHEAR and PONTO 3 SUPER POWER on softband.~Evaluate and compare perception in silence and noise with ADHEAR and PONTO 3 SUPER POWER on softband.~Evaluate and compare the subjective auditory perception with ADHEAR and PONTO 3 SUPER POWER on softband.~Evaluate the satisfaction and use of ADHEAR.