Evaluation of the Learnability and Playability of Pitch Layouts in New Musical Instruments Jennifer MacRitchie and Andrew J. Milne The MARCS Institute for Brain, Behaviour and Development Western Sydney University j.macritchie@westernsydney.edu.au a.milne@westernsydney.edu.au ABSTRACT Certain properties of isomorphic layouts are proposed to offer benefits to learning and performances on a new mu- sical instrument. However, there is little empirical inves- tigation of the effects of these properties. This paper de- tails an experiment that examines the effect of pitch adja- cency and shear on the performances of simple melodies by 24 musically-trained participants after a short training period. In the adjacent layouts, pitches a major second apart are adjacent. In the unsheared layouts, major sec- onds are horizontally aligned but the pitch axis is slanted; in the sheared layouts, the pitch axis is vertical but major seconds are slanted. Qualitative user evaluations of each layout are collected post-experiment. Preliminary results are outlined in this paper, focusing on the themes of learn- ability and playability. Users show strong preferences to- wards layouts with adjacent major seconds, focusing on the potential for learning new pitch patterns. Users con- firm advantages of both unsheared and sheared layouts, one in terms of similarity to traditional instrument settings, and the other to ergonomic benefits. A model of partic- ipants’ performance accuracy shows that sheared layouts are learned significantly faster. Results from this study will inform new music instrument/interface design in terms of features that increase user accessibility. 1. INTRODUCTION Designers of new or extended musical instruments are of- ten concerned with ensuring accessibility for users either with no previous musical experience, or for those who already have training in another instrument, so that they can easily alter/learn new techniques. Several claims re- garding the optimal pitch layout of new electronic instru- ments/interfaces have been made, but as yet there is little empirical investigation of the factors that may enhance or disturb learning and performance on these devices. 1.1 Isomorphic Layout Properties Since the nineteenth century, numerous music theorists and instrument builders have conjectured that isomorphic Copyright: c  2017 Jennifer MacRitchie and Andrew J. Milne et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 3.0 Unported License , which permits unre- stricted use, distribution, and reproduction in any medium, provided the original author and source are credited. pitch layouts provide important advantages over the con- ventional pitch layouts of traditional musical instruments [1–4]. Indeed, a number of new musical interfaces have used isomorphic layouts (e.g., Array Mbira [5], Thum- mer [6], Soundplane [7], AXiS-49 [8], Musix Pro [9], LinnStrument [10], Lightpad Block [11], Terspstra [12]). An isomorphic layout is one where the spatial arrange- ment of any set of pitches (a chord, a scale, a melody, or a complete piece) is invariant with respect to musical trans- position. This contrasts with conventional pitch layouts on traditional musical instruments; for example, on the pi- ano keyboard, playing a given chord or melody in a differ- ent transposition (e.g., in a different key) typically requires changing fingering to negotiate the differing combinations of vertically offset black and white keys. Isomorphic layouts also have elegant properties for mi- crotonal scales, which contain pitches and intervals “be- tween the cracks” of the piano keyboard [13]. Although strict twelve-tone equal temperament (12-TET) is almost ubiquitous in contemporary Western music, different tun- ings are found in historical Western and in non-Western traditions. Isomorphic layouts may, therefore, facilitate the performance of music both within and beyond conven- tional contemporary Western traditions. In this paper, we do not compare isomorphic and non- isomorphic layouts. Instead, we focus on how different isomorphic layouts impact on learnability and playability. This is because there are an infinite number of unique iso- morphic layouts: they all share the property of transposi- tional invariance (by definition) but they differ in a num- ber of other ways that may plausibly impact their usability. For example, successive scale pitches, like C, D, and E, are spatially adjacent in some isomorphic layouts while in oth- ers they are not; additionally, in some isomorphic layouts, pitches are perfectly correlated to a horizontal or vertical axis while in others they are not [14]. In some layouts, oc- taves may be vertically or horizontally aligned; in others, they are slanted. 1 Properties such as these are typically non-independent: improving one (e.g., pitch axis orientation) may worsen an- other (e.g., octave axis orientation). Choosing an optimal layout thus becomes a non-trivial task that requires knowl- edge of the relative importance of the different properties. To shed light on this, the experiment presented in this pa- per explores how two independent spatial transformations 1 With respect to the instrumentalist, the “horizontal” axis runs from left to right, the “vertical” axis from bottom to top or from near to far. Proceedings of the 14th Sound and Music Computing Conference, July 5-8, Espoo, Finland SMC2017-450