Confusingly Similar: Discerning between Hardware Guitar Amplifier Sounds and Simulations with the Kemper Profiling Amp

Abstract

Over the last decades, the simulation of musical instruments by digital means has become an important part of modern music production and live performance. Since the first release of the Kemper Profiling Amplifier (KPA) in 2011, guitarists have been able to create and store a nearly unlimited number of “digital fingerprints” of amplifier and cabinet setups for live performances and studio productions. However, whether listeners can discriminate between the sounds of the KPA and the original amplifier remains unclear. Thus, we constructed a listening test based on musical examples from both sound sources. In a first approach, the psychoacoustic analysis using mel-frequency cepstrum coefficients (MFCCs) revealed a high degree of timbre similarity between the two sound sources. In a second step, a listening test with N = 177 showed that the overall discrimination performance was d’ = .34, which was a rather small difference (0.0 ≤ d’ ≤ 0.74). A weak relationship between the degree of general musical sophistication and discrimination performance was found. Overall, we suggest that listeners are rarely able to assign audio examples to the correct condition. We conclude that, at least on a perceptual level, our results give no support for a commonly accepted pessimistic attitude toward digital simulations of hardware sounds.

The paired A–Not A design within signal detection theory: Description, differentiation, power analysis and application

“…One very recent study is used throughout this paper as an example, and its data are provided as sample data in the Supplementary Material. Düvel et al (2020) conducted a study comparing the sound of original hardware guitar amplifiers with simulations of this specific sound by the Kemper Profiling Amp. The stimuli consisted of pairs with the same musical excerpt performed by the same guitarist recorded either from the original amp (OA, Type A as defined in the section "The paired A-Not A design: Data structure and analysis" of this paper) or the Kemper Profiling Amp (KPA, Type Not A as defined in the same section).…”

“…Response data were based on six pairs of stimuli (i.e., six musical examples each produced in two different ways, one way using the OA and the other the KPA, resulting in 12 stimuli) rated by 177 participants. The study by Düvel et al (2020) was chosen as the sample data set as it employed the exact kind of research design which is the focus of the present paper. Furthermore, the research question is relevant for current discourse in popular music research and easy to understand for non-experts.…”

“…Subsequently, two stimuli, one of stimulus type A and one of type Not A, always form a pair due to their content. For example, it can be the same musical piece performed in two conditions (A and Not A; as in Düvel et al, 2020), the same statement varying in its wording (where wording A is compared to wording Not A), or the same motive in two pictures varying in a particular way (which manifests in stimulus type A and type not A). In a replicated task, several pairs of, for example, musical performances, statements, or pictures would be presented in one study in randomized order.…”

“…In the following sections, these considerations will be illustrated by a study by Düvel et al (2020) on the identification of sounds recorded from original amplifiers and simulations made with the Kemper Profiling Amp. In practice, a person might listen to some music and wonder whether the guitar sound was produced by an original amplifier or by a digital simulation.…”

“…These combinations are explained, and the present article then focuses on the both the non-replicated and replicated paired A-Not A task. Data structure, descriptive statistics, inference statistics, and effect sizes are explained in general and based on example data (Düvel et al, 2020). Documents for the data analysis are given in an extensive online supplement.…”