Tuning fork

Medical tuning forks are small, portable devices with two Y-shaped metal spikes that are used to measure the patient's reaction to sound vibrations. Medical tuning forks are usually made of a combination of metals, including copper and stainless steel, and are sometimes plated with silver or gold. 

The tuning forks resonate at a certain constant tone as striking it against a surface or with an object sets a vibration. During the vibration of the tuning fork, sound frequencies are produced by both the stems and the base. Each diapason when excited produces a primary frequency at 128Hz, 256Hz, 512Hz, 1024Hz, or 2048Hz. Different frequencies can be used for different medical diagnoses.

The medical tuning forks are designed with weights or without weights, with the main difference being that the weights make the ends of the transponder move more, and therefore there is more vibration transferred to the handle