The Music Ball Project: Concept, Design, Development, Performance Alexander Refsum Jensenius ♮♯ ♮ Norwegian Academy of Music Slemdalsveien 11, 0302 Oslo, Norway a.r.jensenius@imv.uio.no Arve Voldsund ♯ ♯ University of Oslo, Dept. Musicology PB 1017 Blindern, 0315 Oslo, Norway arve.voldsund@imv.uio.no ABSTRACT We report on the Music Ball Project, a longterm, exploratory project focused on creating novel instruments/controllers with a spherical shape as the common denominator. Be- sides a simple and attractive geometrical shape, balls afford many different types of use, including play. This has made our music balls popular among widely different groups of people, from toddlers to seniors, including those that would not otherwise engage with a musical instrument. The pa- per summarises our experience of designing, constructing and using a number of music balls of various sizes and with different types of sound-producing elements. Keywords music balls, instruments, controllers, inexpensive 1. INTRODUCTION Although there have been a slight change over the last decade, most commercial, and many experimental, inter- faces for musical expression are still costly, complex, key or button-centric and with square corners. In this paper we report on a side-project we have been running since 2005, the Music Ball Project, where the aim has been to develop instruments/controllers that are inexpensive, simple, fun, human-oriented and with no corners (Figure 1). The Music Ball project has been inspired by ideas of sim- plicity in design and usage [5], the creation of devices that utilise natural affordances [6], and the playfulness that may arise when creating electronic instruments with a limited number of possibilities per instrument [3]. Dependent on the size, a ball can be kicked, thrown, bounced, squeezed, and shaken. Thus it is possible to create many different types of instruments based on a single ball design. Throughout the years we have developed a number of music balls with different visual designs, technical solutions and action-sound mappings. The underlying philosophy has been to create many simple and inexpensive interfaces rather than a few, large and expensive ones. As such, our approach to music ball development is slightly different than some other projects based on the ball shape/metaphor, e.g. [2, 8, 7], that use more complex and/or expensive solutions. For us it has been a requirement that each ball should be as simple as possible on its own, so that we can build a complex Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. NIME’12, May 21 – 23, 2012, University of Michigan, Ann Arbor. Copyright remains with the author(s). Figure 1: A music ball in use at a research fair (left). One microphone-based and one sensor-based music ball (right). setup by having many such music balls that together allow for a rich set of interaction possibilities. Also, our experi- ence of teaching courses on development of new interfaces has shown that students are much more eager to put an effort into their controller if the materials are so cheap that they can actually build more controllers at home. The paper starts with an overview of different types of music balls we have created; ranging from handheld balls to the Music Troll and Big Buoy. Then follows a reflection on various aspects relating to the design/development process as well as the usability of the devices. 2. HANDHELD MUSIC BALLS Any ball can potentially be used as the starting point for a music ball, but we have found two types that we are par- ticularly found of: toy balls for dogs and boat buoys. Toy balls for dogs work well as the basis for smaller handheld balls. They are durable, and are often manufactured in many colours and with many different surface designs (Fig- ure 1). When it comes to developing larger balls, we have found that boat fenders and buoys are practical, since they are both durable and are easily available in many different sizes and shapes. As for most other types of sonic interaction, music balls can be designed to be either acoustic, electronic or both acoustic and electronic, and we will describe these approaches in the following sections. 2.1 Microphone-based music balls Our first music balls were created by stuffing hollow toy balls with materials having different sonic qualities: paper, peas, steel wool, synthetic fibres, etc. The challenge here was to find materials that sounded nice when they were squeezed, but that were also durable enough to withstand heavy use over time. Newspaper sheets, for example, pro- vide a crispy sound, but contracts so quickly that they are more or less useless in our context. Then many synthetic materials, like plastic sponges, work better, since they are elastic and expand quickly after being squeezed (Figure 2).