## Weber Test Principle in Conductive Hearing Loss **Key Point:** In conductive hearing loss, the Weber test lateralizes to the AFFECTED (worse-hearing) ear because bone conduction bypasses the conductive defect and is relatively better preserved than air conduction on that side. ### Mechanism The Weber test uses a vibrating tuning fork placed on the midline of the skull. Sound is conducted via bone directly to the inner ear, bypassing the middle ear and external ear. - **In normal hearing:** Sound is perceived equally in both ears (no lateralization). - **In conductive loss (affected ear):** - Air conduction is impaired (ossicular chain dysfunction, cerumen, TM perforation, etc.) - Bone conduction remains intact - The affected ear perceives the bone-conducted vibration MORE clearly because there is no competing air-conducted sound to mask it - Result: **lateralizes to the affected (worse) ear** ### Contrast: Sensorineural Loss In sensorineural hearing loss, Weber lateralizes to the **better-hearing ear** (the unaffected side) because the cochlea or nerve is damaged, reducing bone conduction perception on that side. **High-Yield:** Weber lateralizes **toward the conductive defect** (affected ear); Rinne shows **bone > air on the affected side**. **Mnemonic:** **WEBER → CONDUCTIVE = AFFECTED EAR** (bone conduction is relatively spared, so it dominates perception). **Clinical Pearl:** This principle is the foundation of distinguishing conductive from sensorineural hearing loss at the bedside without formal audiometry. 
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