The Architecture Hidden Inside Musical Instruments

String instruments, such as guitars, violins, cellos, pianos and so on, produce sound through vibrating strings. These strings are made up of nylon, steel or gut. They can be played by drawing a bow across them, picking with fingers, or by using a pick (1). However, you’ll notice that each stringed instrument, and even different models of the same instrument, produces a unique sound. The different characteristics of these sounds are decided by the thickness of the strings, the type of wood the instrument is made of, the size of the body, but most importantly, the shape of the hollow space inside the body so the sound can vibrate and resonate within. This quality is the result of the nature of string vibrations; when strings are built into the ground or are fixed to a hard object, they vibrate longer since less energy is lost to the surroundings. A downside of this, however, is that the sound fades quickly. The hollow chamber of stringed instruments allows the sound to last longer by reflecting the sound back and forth (2). In the explanation of this process, it is important to mention Helmholtz resonances. Simply blowing into a water bottle, or any container with gas inside (generally air) that has an opening, to produce a note excites a Helmholtz resonance. The bottle, in this case, becomes a Helmholtz resonator. Helmholtz resonators (the typical shape is seen in Figure 1) made it possible to study musical tones and identify the spectral components of a complex sound wave produced by musical instruments in the nineteenth century (3). The hollow body of stringed instruments also acts as Helmholtz resonators. The air within the hollow body resonates similarly to the air in the water bottle when blown from the opening. The hollow body receives the vibration from the strings, to cause sound wavelengths to bounce from the differently shaped walls of the instrument. Along with this, the top surface of guitars, violins and some other instruments have reinforcing bars on the inside, differing from most stringed instruments which have smooth insides. These bars carry vibrations from the bridge area to the rest of the surface. For guitars this is called guitar bracing, for violins, the reinforcing bars are called bass bars.

Figure 1: Typical shape of a Helmholtz Resonator

Apart from setting the color to the instruments’ sounds, these chambers never cease to captivate the eyes with their hidden, yet enchanting once seen, structures. New Zealand-based cellist and photographer Charles Brooks was curious enough to realise and reveal the beauty hidden within stringed instruments to the world. “I never really knew what was going on inside,” he shares, “That was a realm reserved for the luthier. Occasionally, when an instrument was being repaired, you’d get a rare glimpse inside, which was always a thrilling experience” (4). Tee ‘thrill’ he felt guided him to peer inside pianos, brass, and other stringed instruments with special probe lenses and high-resolution cameras, giving birth to “vast and cavernous” (5) images (see Figure 2, Figure 3 & Figure 4).

Figure 2: Lockey Hill Cello circa 1780

Figure 3: Taylor GS Mini Guitar

Figure 4: Kawai Grand Piano

These images not only reveal how different shapes result in different characteristics of sounds, but they also pull the viewer inside the instrument, which is hidden from the eye. The captivating quality also comes from the sensation of history, according to Brooks; “For me, the often so rough inner surfaces show something more about the personality of the instrument than the always shiny outer covering. It is fascinating to look inside the oldest instruments, to discover the space that has vibrated during concerts, perhaps for hundreds of years.” (6). Whilst carrying the traces of history, these crafted chambers carefully hidden inside instruments trap the vibrations and allow them to travel within, bouncing off different sized and shaped walls to create unique, diverse sounds by changing the pattern of wavelengths that are produced.

Works Cited

1. https://www.orsymphony.org/learning-community/instruments/strings/
2. https://exploresound.org/2017/02/physics-stringed-instruments/
3. https://newt.phys.unsw.edu.au/jw/Helmholtz.html
4. https://www.thisiscolossal.com/2022/01/charles-brooks-architecture-in-music/
5. https://www.charlesbrooks.info/#:~:text=In%20my%20Architecture%20of%20Music,sensation%20of%20space%20and%20depth.
6. https://www.domusweb.it/en/photographers/gallery/2022/02/15/the-architecture-of-musical-instruments-in-the-photographs-of-charles-brooks.html