Research Report LGRP#2

This research was executed in 2017
The report from Phase #2 is in the making. On this page we present already a preview of the "Introduction" and the "Abstract":


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

This 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 only to work with professional players for this second phase (ref 2). This methodology for phase #2 also provided the players with a longer evaluation time per guitar. / ....
(to be completed...)


2.1. 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 versus 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; and (3) Non-blind; where the guitarist could fully see the guitars and was aware of the woods used.

2.2. Concise summary of main findings

• 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 (independent of whether the test was blind or non-blind. Like in the previous research (LGRP study phase #1, carried out is 2014 Ref. 1), this result again confirms that non-tropical woods can be utilised to make guitars equal in sound preference to those made with tropical woods.

Different from the Phase #1 study however was the observation that this time the overall preference did not consistently shift in favour of the tropical guitars under non-blind test conditions. This difference between the phase #1 and phase #2 results may be due to: (1) differing sensitivities of the test techniques used, (2) the guitarists realising that we were investigating possible preconceptions or, (3)  preconceptions and/or visual preferences for tropical woods are already beginning to erode Ref. 3 .

• 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 process, called perception, by which the player becomes aware of and interprets external stimuli, showed that assessments by the player can be remarkably subjective .
A supplementary parallel experiment showed, however, that all tested players could clearly identify an extra added control guitar of another model and concept...

(to be completed...)