Influence of distortion on guitar chord structures: Acoustic effects and perceptual correlates

Since the exploration of distortion as a means of expression in the 1950s, the electric guitar has become a primary instrument in popular music, especially in rock and metal music. Despite this development, there is little musicological research on the use and perception of distorted guitar chords. This work aimed at exploring the influence of distortion on guitar chord structures, at identifying acoustic features potentially causing dissonance and at finding explanations for the common use of simple chords in rock and metal music genres. The research followed a two-step experimental design. Based on Terhardt’s (1984) and Aures’ (1985) two-component framework of musical consonance, the main study statistically evaluated acoustic characteristics of 270 electric guitar chords produced with different sound settings, instruments and amplifiers. In a second step, data of a listening test with 171 participants were triangulated with the acoustic results for considering the perceptual perspective as well. The findings largely confirmed distortion to decrease sensory pleasantness especially for complex guitar chords. The parameters of sensory consonance strongly correlated with the listeners’ perceptions. Surprisingly, roughness as the key criterion for dissonance in Helmholtz’ tradition was found the least reliable variable for explaining decreased sonority of distorted guitar sounds.