Which frequencies are used to determine a significant air-bone gap?

• A. 500, 1000, and 2000 Hz
• B. 750, 1500, and 3000 Hz
• C. 1000, 2000, and 4000 Hz
• D. 250, 500, and 1000 Hz

Answer: (A)

Air-bone gap is identified by comparing air-conduction and bone-conduction thresholds at specific frequencies to see if a conductive component is present. The standard set of frequencies used to determine a significant gap is 500, 1000, and 2000 Hz. Why these matter: they cover the key speech-frequency range where hearing loss most affects understanding, and they provide a consistent, clinically accepted window to detect a notable difference between AC and BC thresholds. A gap of about 15 dB or more at any one of these frequencies is typically considered significant, signaling a conductive component.

Other frequency sets exist, but they aren’t the traditional trio relied on for defining a significant air-bone gap. The chosen frequencies align with routine audiometry practice and reflect where conductive losses most often manifest in functional hearing.