In conductive hearing loss, which of the following audiometric findings is characteristic?

Explanation

## Audiometric Findings in Conductive Hearing Loss **Key Point:** In conductive hearing loss, the **air-bone gap** is the hallmark finding. Bone conduction (BC) thresholds are **better (lower)** than air conduction (AC) thresholds because the ossicular chain is bypassed when sound is delivered directly to the cochlea via bone vibration. ### Mechanism Conductive hearing loss affects the external ear canal, tympanic membrane, or middle ear ossicles. The inner ear (cochlea) remains intact and functions normally. - **Bone conduction pathway:** Sound → skull vibration → cochlea (bypasses middle ear) - **Air conduction pathway:** Sound → ear canal → tympanum → ossicles → cochlea (blocked or impaired) Since the conductive pathway is damaged but the sensorineural pathway is intact, BC remains normal while AC is reduced. ### Audiometric Pattern | Parameter | Conductive HL | Sensorineural HL | |-----------|---------------|------------------| | **Air conduction (AC)** | Elevated (worse) | Elevated (worse) | | **Bone conduction (BC)** | Normal (better) | Elevated (worse) | | **Air-bone gap** | Present (AC > BC) | Absent (AC ≈ BC) | | **Weber test** | Lateralizes to affected ear | Lateralizes to normal ear | | **Rinne test** | BC > AC (bone better) | AC > BC (air better) | **High-Yield:** The **air-bone gap ≥ 15 dB** is diagnostic of conductive hearing loss. This gap narrows or closes as the conductive component improves (e.g., after ossiculoplasty). **Clinical Pearl:** Rinne test in conductive loss shows bone conduction heard longer than air conduction (BC > AC), whereas in sensorineural loss, air conduction is better (AC > BC).