What is it?

A two-pronged steel device used by medical practitioners, which vibrates when struck to give a note of specific pitch. Tuning forks, usually C512, are used to assess a patient's hearing.

What is it used for?

This is most commonly done with two exams called the Weber test and Rinne test, respectively. Lower-pitched ones (usually C128) are also used to check vibration sense as part of the examination of the peripheral nervous system