Rinne Test Results: How Badly Can We Be Mistaken?

OBJECTIVE: To establish the extent to which sound amplitudes delivered by a vibrating tuning fork change around its long axis and to evaluate whether such differences in amplitude might change the results of the Rinne test. STUDY DESIGN: Experimental measurements. SETTING: Laboratory setting. METHODS: Setup I: a vibrating tuning fork was handheld and manually rotated around its long axis next to a sound recording device (the simulated ear) in order to record sound amplitude data at a full range of angles relative to the device; files were split into segments in which sound amplitude changed: A (from a maximum to a minimum) and B (from a minimum to a maximum). Setup II: a vibrating tuning fork was machine-rotated, and the angle of rotation, along with the sound amplitude, was automatically recorded through a single full rotation. RESULTS: The angles of 0° and 180° (which equate to the established best practice in Rinne testing) were associated with the highest sound amplitudes. All other angles decreased sound amplitude. The greatest decrease in amplitude was recorded at 51° and 130°. This difference ranged from 9.8 to 34.7 dB, depending on the initial amplitude. CONCLUSION: The outcome of a Rinne test can be affected if attention is not paid to the precise angle at which the tuning fork is held relative to the ear. The potential of this effect will be greater when high background noise or patient hearing loss requires that the tuning fork be vigorously excited to obtain high sound amplitudes.