Tuning forks – indispensable for complete patient examinations
Medicinal tuning forks will forever be associated with names such as Weber and Rinne or Rydel Seiffer. Every carefully-done, complete physical examination of a patient involves the use of a tuning fork.
The graduated tuning fork developed by Rydel Seiffer c 128 Hz/C 64 Hz is a standard in the field of neurology and is also probably the most well-known neurological tuning fork. This calibrated tuning fork has removable dampers with a 1/8 scale graduation and is used to identify a loss of the sense of vibrations, and is used to diagnose polyneuritis which can occur e.g. along with diabetes mellitus. With the screwed-on dampers, the fork vibrates at 64 Hz. Reference marks for exact calibration of the original KaWe tuning fork can be found on the back side of the fork tines. It is in this configuration that the tuning fork is used in vibration examinations. The screwed-on plastic foot allows for a gentle transfer of the vibrations from the tuning fork to the patient. Without the dampers, the instrument vibrates at a frequency of 128 Hz and is used for simple hearing and bone conductivity tests. This tuning fork method for testing sensibility, which was first used in 1903, is still considered to be the most dependable and safe even today.
The Weber experiment serves to identify a laterality of the sense of hearing with the use of a tuning fork. Physiologist Ernst Heinrich Weber (1795–1878) of Leipzig first recorded this in experiment in 1825. Hildesheimer psychologist Heinrich Rinne (1819–1868) amended the test in 1855. Whereas the Weber test serves to compare the sound perception of each ear by means of bone transmition, the Rinne test compares air and bone transmition. Both tests together form a standard test for the examination of hearing damage as well as of the eighth cranial nerve.