Tuning forks in 128 Hz, 256 Hz, and 320 Hz frequencies
These tuning forks are individually crafted of chromed forged steel. It’s stamped with the musical scale note sounded by the fork and the frequency at the base of the tine of each fork. Available in 128 Hz, 256 Hz, and 320 Hz.
How tuning forks work
Sound waves a produced by vibrating objects. A tuning fork produces sound waves from the form of its two-pronged fork with the prongs (tines) formed from a U-shaped bar of metal. It resonates at a specific constant pitch when set vibrating by striking it with an object. It emits a pure musical tone once the high overtones fade out.
How a tuning fork’s size affects its pitch
A tuning fork’s pitch depends on the length and mass of the two prongs. When the tuning fork is struck, little of the energy goes into the overtone modes; they also die out correspondingly faster, leaving a pure sine wave at the fundamental frequency. Commercial tuning forks are tuned to the correct pitch at the factory, and the pitch and frequency in hertz is stamped on them. They can be retuned by filing material off the prongs. Filing the ends of the prongs raises the pitch (shorter tines move less distance and thus move faster), while filing the inside of the base of the prongs lowers it.
Why a tuning fork’s shape is important
The reason for using the fork shape is that it can then be held at the base without dampening the oscillation. That is because its principal mode of vibration is symmetric, with the two prongs always moving in opposite directions, so that at the base where the two prongs meet there is a node (point of no vibratory motion) which can therefore be handled without removing energy from the oscillation (dampening).
Tuning forks in medical diagnosis
Tuning forks remain a preferred method of testing for certain types of hearing loss. In a method known as a Rinne test, a doctor first holds a humming tuning fork to your skull and, using a stopwatch, times how long you can hear it. The doctor then strikes the tuning fork again and times how long you can hear it when it’s held next to your ear. If you can hear the tuning fork through your jaw longer than you can hear it against your ear, you have a problem conducting sound waves through your ear canal.
In a similar test (known as the Weber test), a vibrating tuning fork is held in the middle of a patient’s forehead. By figuring out which ear hears the tuning fork the loudest, the doctor can zero in on which ear is damaged.
Tuning fork notes
Note: You can see the blur of the tines vibrating. To exaggerate the effect, dip the tines in water.