The clinking of glass is pleasing to the ear. In some regions of Poland, the breaking of dishes is believed to bring good luck to newlyweds. Clinking filled glasses is a confirmation of the wishes expressed in a toast. Finally, the sound of glass coming from the kitchen heralds a delicious meal. Depending on various factors, glass produces different sounds. This phenomenon is used by musicians who play glass instruments. Why does glass make a sound, and what determines its pitch?
How is the sound of glass created?
The melodic sound of glass was discovered in the Middle Ages - even then, people attempted to play the first concerts on glasses tuned with water. However, it is only relatively recently that scientists have been able to accurately describe and verify how this is possible. Thanks to computer analysis, they even compare the sound wave produced by a wet glass to that created by church bells.
When a glass is filled with water, and a gently wet finger rubs its rim, a melodic sound appears, and waves form on the surface of the liquid. This happens because the glass vibrates, also inducing movement in the water. It turns out that the finger thus "stretches" the glass in one direction and "compresses" it perpendicularly, and the wave generated on its circumference causes not only the water but also the air inside to vibrate – just like in the resonant body of traditional instruments. The more liquid in the glass, the lower the sounds, because more vibrational energy is transferred to it – and vice versa: the less liquid in the glass, the higher the sound can be obtained. If glasses were placed side by side and one was made to vibrate, it would transfer energy to the other and also make it "play."
In practice – to try your hand at the fun of playing glasses - all you need to know is how increasing or decreasing the amount of water in a vessel works, and what sounds will be produced by empty glasses or tumblers of different thicknesses. Experts and enthusiasts in this field can play the most complex classical music compositions on them – all thanks to the glass instruments made from them!
Glass instruments
Instruments made of glass are an element of many cultures around the world. They originated hundreds of years ago in China or Persia, and in the Middle Ages they also appeared in Europe. Playing glasses is not an extravagant idea of modern artists, but a passion that was pursued in the times of kings and knights.
In 1743, Richard Pockridge from Ireland constructed the "angelic organ," which was nothing more than a set of glasses appropriately filled with water. He gave concerts on his instrument, teaching this craft to others! 18 years later, the first textbook promoting playing on glasses and other glass instruments was published. Another such instrument was the verrillion, for which its creator – Christoph Willibald Gluck – composed a piece with the accompaniment of a chamber orchestra. He so delighted the London audience with it that contemporary journalists compared their experience to reading Shakespeare!
Around the same time, the future president of the United States – the versatile inventor Benjamin Franklin, inspired by a concert he heard on the angelic organ, invented the glass harmonika. It differed from other glass instruments in that its individual elements were not filled with water, but were cast from glass of different thicknesses during the construction process. This alone was enough for the vibrations caused by the player's wet fingers to create sounds of different pitches. The artistic value of this instrument is evidenced by the fact that the greatest European composers, such as Beethoven and Mozart, played and created on it. Historians refer to articles and opinions of witnesses who claimed that the music played on the glass harmonika hypnotized and put listeners in a trance... Perhaps that is why fascinated writers and poets metaphorically evoke it in their works – its traces can be found, for example, in the third part of Adam Mickiewicz's "Dziady."
In the mid-19th century, doctors believed that playing on glass could be beneficial for people suffering from mental disorders and used methods similar to today's music therapy. However, there were opponents who put forward theories that these sounds destroyed the nervous system. They also pointed out that the lead contained in the glass of that time, which entered the player's digestive system through hands moistened with water and touching the bowls, could cause a dangerous disease - lead poisoning. Their voice was strong enough (and in the case of lead's harmfulness true – several artists died because of it!) that this method of music-making faded into oblivion for many years.
Today, playing on glass is considered an avant-garde field of music. For these purposes, a modern version of the glass harp is used, which consists of only the bowls of glasses arranged in three rows, with glass of such thickness that they produce different sounds. Modern glass is, of course, completely safe! The instrument's elements are hand-blown and custom-tuned. The harp also includes containers for moistening hands, because although the glasses themselves do not require filling with liquid, it is impossible to produce sound from them without wet fingers. This instrument costs over 12,000 PLN – but you don't have to invest in it to try playing on glasses yourself!
Playing on glasses
Playing on glasses with water is within easy reach. Simply set up a set of three or six glasses on the table and prepare about two liters of water. The first glass should be almost completely filled with water – this will produce the lowest sound. The next should have 1/4 less water. The next will have half the water of the first, and so on until the last glass – the one with the least water will have the highest sound.
After wetting your hands, slide your finger along the rim of the glass to make it produce a sound. People with a skilled musical ear will quickly be able to arrange six basic sounds and will be able to tune the glasses by pouring out or adding the appropriate amount of liquid. With six sounds, you can already play several simple melodies – it's worth learning at least two or three and astounding your friends and family at the next gathering!
When the sound of glass causes pain
Although the sound of glass is usually pleasant and melodic, and the brain easily associates it positively with a meal, some of its variations can cause shivers. These include, among other things, a fork or knife scraping across a plate. This happens because it is a high-pitched sound, almost extreme on the human hearing scale, and loud. One cannot become immune to it – the brain will always associate it with unpleasantness. And although the melodic sound of glass inspires artists and still delights during beautiful performances on glasses, this particular variation has been classified by scientists as one of the ten most common and irritating sounds in the world.