This is a French pilot study in the Toulouse University Hospital that will include a minimum of 30 patients with proven unilateral or asymmetric otosclerosis. Each one will receive a hearing aid for a minimum of 2 months and then undergo otosclerosis surgery.

Otosclerosis is the main cause of acquired hearing loss in young to middle aged Caucasian population. Social, personal and medico-economic impacts triggered by this affection make it a major public health matter. Historically, the surgical treatment of otosclerosis has always been considered one of the best indications of otologic surgery. The external hearing aid was then an alternative to surgery considered as a more restrictive and less effective management of otosclerosis. With the recent technological developments of hearing aids, comparing these two treatments otosclerosis should be studied. The absence of scientific data from the literature concerning this subject justifies this study which purpose is to describe the evolution of the quality of life and hearing performance of a same patient after taking over by these two approaches.

This is a French pilot study in the Toulouse University Hospital that will include a minimum of 30 patients with proven unilateral or asymmetric otosclerosis. Each one will receive a hearing aid for a minimum of 2 months and then undergo otosclerosis surgery.

The primary outcome will be based on a study of the quality of life (score of 0-100 to quality of life validated questionnaire Glasgow Health Status Inventory (GHSI)). The questionnaire will be given to the patient at the pre-enrollment visit, after a period of two months of external hearing aid trying and 2 months after the surgery. Secondary outcomes will be studied: simple hearing performance (voice and tone audiogram), complex hearing performance (speech audiogram in noise recognition stamp), specific questionnaires for hearing (SSQ), for hearing aids (APHAB, GBI equipment), for tinnitus if present (THI and VAS discomfort / intensity) or for surgical treatment (surgery GBI). Data about treatment's side effects and the number of potential patients refusing surgery after testing the hearing aid will also be collected.

Inclusion Criteria:

Nosological criteria:

• Unilateral or bilateral asymmetric otosclerosis
• Conductive hearing loss of at least 30 dB with an average loss Rinne means greater than or equal to 20 dB (on frequencies 0.5, 1, 2, 4 kHz)
• Normal tympanum
• Temporal bones CT-scan showing radiologic signs of otosclerosis

Related to treatment criteria:

• No previous treatment for the otosclerosis

Exclusion Criteria:

Disease's related criteria:

• Far advanced otosclerosis defined as less than 95dB air conduction at all frequencies or lower bone conduction 55dB on at least one frequency
• Cochlear otosclerosis objectified on the temporal bones Ct-scan
• Others clinical or radiological diagnostics: cholesteatoma, tympanic membrane perforation, geyser's syndrome, ossicular dislocation, ossicular malformation, tympanosclerosis.

Associated pathologies: tympanic retraction, effects of chronic otitis, tubal dysfunction.

Criteria about proposed treatments:

• Anesthesia contraindications
• Operative contraindication: clotting disorders, tympanum retraction and tubal dysfunction, geyser's syndrome, single ear, patient refusal.

Criteria relative to study's explorations: Language barrier (questionnaires, tests), cognitive disorders.

Criteria relating to previous treatment: Previous hearing aid or surgery Administrative criteria: Patients minors, incapable adults, adults under guardianship, incapable of giving consent.