Which combination of earmold design factors contributes to emphasizing high-frequency amplification?

• A. Sound bore size
• B. Libby horn
• C. Vent width
• D. All of the above

Answer: (D)

Shaping the acoustic path from the hearing aid to the ear canal can emphasize high-frequency amplification. A smaller sound bore increases the canal’s acoustic impedance, which tends to dampen low frequencies more than high frequencies, making high-frequency output relatively stronger. The Libby horn is a flare in the earmold canal that improves impedance matching and energy transfer at higher frequencies, reducing reflections that would dampen those frequencies. A narrower vent further limits low-frequency leakage, shifting the balance toward higher frequencies. Put together, these features all push the sound toward the higher end of the spectrum, giving more high-frequency amplification.