Research Report LGRP#2
This research was carried out beginning 2017.
On this page we present the introduction and the abstract of the study.
Scroll further down to see the list with the used wood species per guitar.
The full LGRP#2 Research Report will be published when the study of our partner François Gautier (Professeur en Acoustique/vibrations, Laboratoire d'Acoustique de L'Université du Maine) will be finalised and published.
For over a few centuries it has been widely believed that high quality classical and steel-string guitars – their soundboards being the major exception – have to be constructed from rare and exotic timbers.This applies particularly to backs and sides (rosewood/mahogany), fingerboards, bridges (ebony/rosewood), and necks (mahogany/spanish cedar).
Indeed most builders and players alike consider the now archetypal tropical hardwoods as the preferred, if not the only choice for instruments of the highest tonal quality. Whilst some non-tropical back and side woods have become established for certain applications - most notably cypress for flamenco guitars and maple for the more affordable “student” classical models - experimentation with other, alternative non-tropical woods has only ever occurred on a small scale and has not delivered the empirical proof required to indicate that such woods can be regarded as acceptable tonewoods.
• LGRP study, Phase #1 / 2014
Until the Phase#1 LGRP comparitive study on sound preferences between guitars made from tropical woods, and guitars made from non-tropical woods (carried out in 2014 ref 1), there has been no reliable, scientific investigation into the suitability of non-tropical species such as alder, ash, cherry, plane, birch, poplar, chestnut etc. for guitar building.
In order for the widespread belief in the tonal superiority of tropical wood in guitar making to be validated, research would be required to prove that, under blind conditions, experienced guitarists and listeners show a clear preference for guitars made from tropical woods, and are able to reliably distinguish them from their non-tropical counterparts.
The LGRP phase #1 study, however, showed that first-rate guitar players and experienced listeners alike were unable either to register a clear preference between the two sets of guitars or to distinguish between both wood groups at anything better than chance levels. Furthermore, under non-blind conditions, the non-tropical wood guitars show, on average, a marked fallback in preference of some 50%. This would indicate that sound perception is strongly influenced by visually transmitted information such as the aesthetic qualities of an instrument, or the preconceptions surrounding ‘good’ and ‘bad’ tonewoods that their recognition allows.
• LGRP study, Phase #2 / 2017
The phase #2 study was designed to retest the findings from the phase #1 study, but this time (a) with a larger number of guitars and players, (b) with the tests executed in 3 countries, (c) with guitar ‘pairs’ (1 guitar made from tropical wood and one guitar made from non-tropical wood, by the same builder), (d) to investigate if cognitive and/or visual information about the instrument would influence the scores and/or the sound perception, and (e) to get an idea of the ability of the guitarists to objectively assess the sound qualities of the tested guitars.
The tests of the first phase were executed by professional players and listeners, as well as by public audiences. The results showed that the players were the most reliable in their ability to assess the guitars. Therefore we chose to work only with professional players for this second phase. This methodology for phase #2 also provided the players with a longer evaluation time per guitar. / ....
1. About the tests
For these playing/listening tests 44 guitars have been made by 22 builders over 3 lutherie schools based in 3 countries
- 16 classical guitars were made in Cmb, Belgium
- 4 classical guitars were made in Newark college, UK
- 12 steel string guitars were made in Cmb, Belgium
- 12 steel string guitars were made in Ikata, Finland
All classical guitars were made to the same model (design and plan by Walter Verreydt & Karel Dedain, contour based on Bouchet). All steel string guitars were made to the same model: ‘Martin 00’ (plan: Adrian Lucas)
Each builder made a matched pair consisting of one guitar made from local non-tropical wood and one guitar made from traditionally used tropical wood, exept for the top plate which, for all guitars, was made from European spruce.
For testing purposes, each pair was placed in a group consisting of 4 guitars from 2 builders. Several groups were assessed in ‘test sessions’, the amount of groups depending of the number of guitars made per country. In total, over the 3 countries, 20 guitar players carried out a session. In this way 22 ‘non-tropical guitars’ were compared to 22 ‘tropical guitars’.
The tests were designed to: (1) compare the tropical guitars to the non-tropical guitars; (2) to see if preconceptions and/or visual information would influence the scores and/or the perception of the sound and (3) to investigate the amount of subjectivity/objectivity in the players perception of the guitars. To do this, each group of guitars was tested in 3 parts.
1. Blind; where the guitarist is blindfolded and cannot see the guitars
2. Blind with information; where the blindfolded guitarist is now given (sometimes misleading) information over the woods used
3. Nonblind; where the guitarist could fully see the guitars and was aware of the woods used.
2. Concise summary of main findings
Tropical or non-tropical?
In total 840 individual assessments were carried out over 44
guitars. Averaging the scores for all guitars, and converting to a percentage score, gives an average of close to 50-50 (with no more than 5% differences between the 2 groups per assessment).
Like in the previous study carried out in 2014, this result confirms once again that assessors, in blind conditions, are not able to distinguish between guitars built with tropical wood or with non-tropical wood, which means that non-tropical wood species can be used to build guitars with equivalent sound qualities to those made with tropical wood species.
Given this remarkable and, by the standards and beliefs unexpected result, one might wonder to what extent the wood type itself, especially for the back and sides, is responsible for the final sound, and this in comparison with the impact on the sound of the top, including braces, bridge, bridge plate, brace patterns etc, and all the possible variables of those elements...
Subjectivity of human perception...
When, in blind conditions, the player was misinformed to believe that one and the same guitar were two different guitars in a group of 5 guitars (so, actually there were only 4 guitars), nearly all players developed in their brain 2 different ‘soundscapes’ of the 2 identical guitars.
The neurophysiological processes, called perception, by which the player becomes aware of and interprets external stimuli, showed that assessments by the player can be remarkably subjective. The subjectivity not only varied from person to person but was also noticeable within a relatively short period of time in a same person. And this last point was observed in the majority of testers...
The full LGRP#2 Report will be published when the research of our partner François Gautier (Professeur, Laboratoire d'Acoustique de L'Université du Maine) will be finalised, published and integrated in our report. This study by F. Gautier was carried out with the same 16 classical guitars which were made in Cmb. (Also the online test was carried out with those 16 guitars.)
Below a chart of the Acoustic Signatures of the 8 tropical and the 8 non-tropical guitars as measured by F. Gautier seeming to confirm the results of our multiple LGRP investigations.
The guitars made for phase#2 (front and back view)
and the used wood species per guitar for back/sides, neck, fingerboard and bridge
Used wood species per guitar for back/sides, neck, fingerboard and bridge