The otologist's tuning fork examination--are you striking it correctly?

Objective: To determine if the manner in which a tuning fork is activated affects its vibrational response.

Study design: Diagnostic test assessment.

Setting: Hearing Center of Excellence laboratory.

Subjects and methods: A Polytec OFV-5000 scanning vibrometer was used to measure the vibrational response of 256-Hz, 512-Hz, and 1024-Hz tuning forks after activation. The tuning forks were activated to varying intensities by striking 4 unique surfaces: the head, palm, a metal surface, and a wood table.

Results: The fundamental frequency of the individual tuning fork was the dominant observed frequency in all testing scenarios. Additional nonharmonic frequencies were noted when the 256-Hz and 512-Hz tuning forks were struck off metal and wooden surfaces.

Conclusions: Additional nonfundamental sound frequencies produced secondary to striking a tuning fork off a metal object or a wooden table could affect clinical tuning fork examination and complicate decisions regarding surgical candidacy.