09/11/2025
Key Clinical insights – Tuning Fork Tests
Principles
1. Never strike the tuning fork on a metallic surface — it causes distortion and produces unwanted overtones.
→ Tap it gently on your knee or a rubber pad.
2. Resonant frequency depends on mass and stiffness:
↑ stiffness → ↑ frequency.
Therefore, a shorter and thicker fork gives better clinical performance.
3. Hold the fork parallel to the ear canal — not perpendicular — so that the acoustic axis is directed toward the canal.
4. Hold the fork firmly by the stem to avoid damping of vibrations.
5. 512 Hz is the best clinical choice because:
It lies in the middle of the speech frequency range.
128 Hz is felt more than heard (vibrotactile), while 1024 Hz decays too quickly.
512 Hz gives optimal audibility and duration.
Conditions
6. Perform the tests in a quiet room.
7. Use a small-base tuning fork — large bases may touch the auricle and cause misleading results (especially in children with small mastoids).
Weber Test
8. Common positions: forehead, vertex, nasion, occiput, or natural (non-denture) teeth.
9. When placing the fork, stabilize the patient’s head by resting your other hand gently on the occiput to provide counter-pressure.
→ Hold the fork for about 3–4 seconds.
10. The Weber test is very sensitive — a difference of only ≈5 dB can cause lateralization.
Rinne Test
11. For Air Conduction (AC): hold the fork about 25 mm from the ear canal entrance.
12. For Bone Conduction (BC): place the base on the McWinney triangle (posterior to the pinna on the mastoid).
13. Perform the test twice (AC→BC and vice versa) to confirm reliability.
14. The Rinne has two aspects:
Intensity test (which sounds louder).
Duration test (if both sound equally loud).
15. Rinne can detect a conductive loss of ~17.5–30 dB; it has limited sensitivity in smaller gaps (< 15–17 dB).
16. False-negative Rinne:
Occurs in severe or profound SNHL on the test side.
Bone vibration crosses the skull and is heard by the better cochlea (cross-hearing).
Requires a fully masked pure tone audiogram for confirmation.
Note
Aluminium forks produce more overtones (used in sound therapy).
Steel forks are superior for clinical audiological testing due to stable resonance.
