Copper Tuning Fork

Tuning forks are so named because they are used to help tune musical instruments, but they also have a variety of other uses. They are used by audiologists to test for certain kinds of hearing loss, by the police to calibrate the radar guns used to identify speeding vehicles, and by alternative healers as an (unproven) way of improving mental clarity and physical energy. They can also apparently be used by medics to detect a bone fracture in a pinch if no x-ray is available. The applications all rely on the fact that when a tuning fork is struck, that energy is converted into vibrational energy, and its tines oscillate at a particular frequency to produce a specific pitch of note.

This brass tuning fork is one of a set of 16 made in 2009 by our Director Zoe Laughlin as part of her PhD research. Together these tuning forks investigate the acoustic properties of materials and demonstrate the physics of sound and vibration. Three principle factors influence the production of sound by a tuning fork: the shape of the fork, and the density and elastic modulus (a measure of stiffness) of the material from which the fork is made. Each of the set of tuning forks is the exact same shape, but is made from a different material (an array of metals, woods, plastics and glass). Playing these tuning forks allows us to directly compare how the density and elastic modulus of each material affects the sound the fork produces.

When these tuning forks are struck, the density and elastic modulus of the material determine how much energy is absorbed and how much is converted into vibrations and audible noise. These material properties will also affect how high or low the note that is produced is (acoustic pitch) as well as how long the tuning fork rings for (acoustic brightness).

The brass tuning fork has a bright yellow metallic appearance, though this appearance changes over time as the result of handling and exposure to air. If the fork is never cleaned, the surface of the material oxidises to produce a darker and duller protective layer. When played, the brass tuning fork gives a loud bright tone of a pitch higher than the copper fork but lower than the blued steel fork. The note is clearly audible when held some distance from the ear and makes a clear, bright and sustained sound. The duration of the note produced is longer than any other of the forks we have made and the vibrations continue to be felt in the hand even after they are no longer detectible by the ear due to its optimal rations of density and elasticity. Brass is an alloy of zinc and copper and is commonly used in the making of percussive and wind instruments. On hearing the bright, loud and resonant sound produced by the brass tuning fork it is easy to appreciate the effect this material has on the ability of an object to produce sound. As a material it is also prized for its ability to be easily worked and formed by hand, thus enabling the creation of the complex systems of pipes and tubes that characterise many instruments made from brass.

Read more about our sensoaesthetics research here.