Glass 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 glass tuning fork is one of a set of 16 made in 2009 by our Director Zoe Laughlin as part of her PhD research. Together they 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).

Clear and transparent in appearance, the glass tuning fork is cool to the touch and has a different shape to the metal, wood and polymer forks due to the method of its manufacture. To make a glass tuning fork with a square cross section, identical to the metal ones, would require a water jet cutter. We did not have access to this technology but instead worked with a glass blower to make this fork from glass rods using lampworking techniques. Two tuning forks were made like this – one to match the pitch of a 440Hz (the note of A) concert pitch tuning fork and the other to match the dimensions of a steel tuning fork that we found with a cylindrical cross section.

On playing this tuning fork, a clear, bright and high tone - the highest note of all our forks - can be heard, and the note sustains for a reasonable period of time. But be careful! The fragile nature of glass means that it can easily shatter upon playing, especially if care is not taken when striking to produce a note.

Read more about our sensoaesthetics research here.