The two violins built by researchers. Photo: Martina Meincken
- The violins of the world are mostly made of spruce and maple, trees grown in the northern hemisphere.
- What if African woods native to the southern hemisphere were used to create an African violin?
- Results of a new study show that African wood species produce an instrument with a beautiful, slightly different sound.
Tonewoods are species of wood that possess certain desirable properties that make them suitable for making musical instruments, such as wind or string instruments – such as a flute or a violin. All good tonewood should be cut radially, which means that the lines formed by the rings are perfectly parallel on the surface. It should have an even-grained structure, be free from defects, and not shrink or swell noticeably with environmental changes.
The violins of the world are mostly made of spruce and maple, trees grown in the northern hemisphere. But what if African woods native to the southern hemisphere were used to create an African violin? We set out to test the native woods of the continent and found that four species of wood not only worked, but worked well. Then we created two complete violins from them to test their sound.
What is the right wood for a violin?
The soundboards are part of the body of the violin. They are made of wood which should resonate by amplifying the oscillation – the vibration – of the stringed instruments. They should be light but stiff enough to handle the tension of the strings and should spread the sound well in the direction of the grain of the wood. If the density of the wood is not uniform, the sound waves could scatter. This should make (sub)tropical wood species good candidates for soundboards, as the lack of pronounced growing seasons results in a wood with barely visible tree rings and little variation in density.
However, high-quality violins are made from the same wood species around the world: spruce as the soundboard (top plate) and maple as the frame (back). While luthiers seem to be more adventurous in using alternative wood species, luthiers tend to use only these traditional wood species. Good quality wood usually comes from colder regions, such as Canada or the European Alps, where trees grow more slowly, resulting in a uniform wood structure with fewer density fluctuations.
The soundboard at the front of the violin should transmit sound well, while the frame at the back should have a high modulus of elasticity to support the soundboard, while diffusing sound well. Both parts should have a fairly low density to avoid unnecessary weight, which would make playing the instrument uncomfortable.
Based on all these requirements, our research team characterized several southern African wood species in order to identify possible alternatives for violin making. We finally decided that yellowwood (Podocarpus latifolius) and Knysna Blackwood (Acacia melanoxylon – which is strictly speaking not indigenous, but which has established itself in the natural forests of southwestern South Africa since the early 1900s) would be suitable as a soundboard. Native to West Africa, sapele (Cylindrical entandrophragma) and pear tree (Olinia ventosa) from South Africa were most suitable as structural panels.
Test the African violin
Hannes Jacobs is a professional luthier from Pretoria, South Africa. A luthier is someone who builds stringed instruments. He agreed to make a full-size violin from yellowwood and sapele. We wanted to make sure that the quality of the instrument would be comparable to good quality commercial instruments.
The sound quality of this instrument, baptized “African violin”, was then compared to a violin made from traditional wood species by the same luthier, with the same methodology. Both instruments were played by the same player with the same bow.
The sound quality of the two violins was determined by recording audio frequency spectra – scales – of different single notes to analyze discernible harmonics. It is a musical tone that is part of the harmonic series above a root note. Good sound quality usually consists of many harmonics at higher frequencies.
The African fiddle has been played by various musicians on separate occasions, and all have agreed that its sound is quite different from that of most other fiddles. The general assessment was that it has a very full and powerful sound with a strong low end that projects well in the room.
The resonance frequencies of the African violin are visibly different from those of the conventional violin. It has stronger harmonics in the low frequency range, resulting in a full sound that carries well. It also shows more harmonics at higher frequencies. For frequencies above 3 kHz, the African violin shows significantly higher amplitudes, giving it a somewhat harsh sound, whereas the lower amplitudes of the conventional violin result in a softer sound. The African fiddle is probably best suited to modern or jazz music.
The physical properties of the wood used for the African violin suggest that it radiates less well in the high frequency range than spruce wood. Contrary to this expectation, the African violin exhibits larger resonance peaks at high frequencies than the conventional violin. Resonance peaks are at the frequencies where the soundboard oscillates the most and they make up the musical notes you hear. The more resonant frequencies are audible, the fuller the sound.
The results of our study show that African wood species are clearly suitable for use as tonewoods in violins. They are able to produce an instrument with a beautiful sound, although slightly different.
The African fiddle has a noticeably louder sound in the low frequencies which propagates very well in the room. It also showed more overtones with higher amplitudes in the high frequencies, giving it a harsher sound than the conventional violin. Yellowwood and Sapele can be used to make string instruments with a powerful and sonorous sound.
Martina Meincken is associate professor at the University of Stellenbosch.
This article was first published by The conversation and has been republished here under a Creative Commons license.