DrumTop: Playing with Everyday Objects

Akito van TroyerMIT Media Lab

75 Amherst StreetCambridge, MA, 02139akito@media.mit.edu

ABSTRACTWe introduce a prototype of a new tangible step sequencerthat transforms everyday objects into percussive musicalinstruments. DrumTop adapts our everyday task-orientedhand gestures with everyday objects as the basis of musicalinteraction, resulting in an easily graspable musical interfacefor musical novices. The sound, tactile, and visual feedbackcomes directly from everyday objects as the players programdrum patterns and rearrange the objects on the tabletopinterface. DrumTop encourages the players to explore themusical potentiality of their surroundings and be musicallycreative through rhythmic interactions with everyday ob-jects. The interface consists of transducers that trigger ahit, causing the objects themselves to produce sound whenthey are in close contact with the transducers. We discusshow we designed and implemented our current DrumTopprototype and describe how players interact with the inter-face. We then highlight the players’ experience with Drum-top and our plans for future work in the fields of musiceducation and performance.

KeywordsTangible User Interfaces, Playful Experience, Percussion,Step Sequencer, Transducers, Everyday Objects

1. INTRODUCTIONThe DrumTop project illustrates our effort to design andimplement a new musical interface that takes advantageof everyday objects as a source of musical inspirations formusical novices. The goal in making DrumTop is to: cre-ate a simple physical interface that gives voice to everydayobjects, afford self-expression and immediate engagementfor novices, and encourage novices to explore the musicalpotentiality of their surroundings through musical interac-tions with everyday objects. Many new musical interfacesfor musical novices focus on expressing music by means ofelectronic and digital sound productions [2]. By building aprototype, we seek to expand the possibilities of new musicalinterfaces for novices that produce sounds from real worldobjects themselves in intuitive fashion. The DrumTop inter-face provides novices with ways to explore rhythm patterns,sounds, and their combinations through task-oriented handgestures with everyday objects. In addition to hearing the

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rhythm patterns they created, players also visually and tan-gibly receive feedback through the objects.

Initial feedback from players suggests that DrumTop canbe used to explore musical structures and the interactionsamong different objects, sounds, and patterns. Using ev-eryday objects as a central ingredient of a musical interfacedesign facilitates a fun and exciting experience, encourag-ing experimentation and collaboration among players. Thefeedback also suggests musical novices, especially children,would see DrumTop as an accessible and playful way tolearn musical patterns, and that performers and artists willfind it a rich tool for collaboration and playful interactiveperformance. We seek to further evaluate DrumTop as atool for music exploration, teaching, and performance.

Figure 1: A player interacts with DrumTop usingfound objects. Almost any objects can be placed onthe tabletop surface provided that the objects arenot excessively large and can touch the transducers.

2. RELATED WORKSEveryday objects are a fascinating source of musical ac-tivities and transforming everyday objects into percussivemusical instruments is an old concept: music and new mu-sical instruments often have their origin in objects aroundus such as household objects, natural objects, and craftingtools [17]. The concept of transforming household objectsinto musical materials was suggested by Erik Satie [6]. JohnCage has frequently used found objects in his compositionssuch as Water Walk [4]. Many of us may have grown upplaying and learning music through beating on buckets andkitchen utensils as composer Tod Machover did [15]. Withinthe NIME community, a countless number of projects that

explore the use of everyday object in the musical contextexist [7] [18] [19]. Perry Cook highlights that ”everyday ob-jects suggest amusing controllers” [5], and DrumTop makesfull use of everyday objects to facilitate a creative musicalexperience for novices.

2.1 AutomationA number of related works explore transforming everydayobjects into percussive instruments in an automated fash-ion. Duper/Looper, Beatbox, and Buonda focus on a mod-ular tangible drum machine interface that can simply be at-tached to or placed on top of physical objects (Figure 2) [13,10, 11]. Their interaction models are based on the relocationof knockers, actuators typically composed of solenoids orservo motors, which act in the manner of the user’s knock-ing hand gestures. The user simply places the knockers ontop of objects or attaches them to the objects that theywould like to generate a rhythm from. DrumTop resemblesthese projects in that the rhythmic patterns are automatedand the sound production technique does not rely on digi-tal signal processing but on the sounds of physical objectsthemselves.

2.2 Tabletop Synthesizer/SequencerSeveral works make use of physical objects to synthesizedigital sound and generate rhythmic patterns by analyzingthem on the fly. We pay special attention to the core me-chanics of the interaction model that these types of projectsemphasize. These projects freely and quickly move aroundphysical objects on a tabletop surface to progressively af-fect the sound outcome. Golan Levin’s Scrapple is a table-top musical instrument with which users arrange a groupof physical objects with different sizes and shapes on thetable [14]. The instrument scans the table and synthesizessounds in real-time. It does this by interpreting the objectson the table as spectrographic sound-events.

Reactable, a tabletop tangible musical interface, is capa-ble of having multiple users locally or remotely collaborateto create electro-acoustic music [12]. Users move physicalartifacts that have fiducial markers underneath them onthe tabletop surface to construct and manipulate musicaltopologies. Other examples of tabletop tangible musical in-terface projects include Audiopad [20] and Jam-O-Drum [3].The Bubblegum Sequencer is a step sequencer with a physi-cal interface with which users create and perform percussiveelectronic music by arranging gumballs on a tabletop inter-face with gridded holes [8]. Sound samples are mapped tothe color of the gumballs, and they are sequentially playedat the appropriate time as users place gumballs on the holesof the interface. DrumTop is insipired by their tabletopinterface design approach that makes the manipulation ofmusic familiar and easy to understand for novices.

3. DESIGNING PLAYFUL EXPERIENCE3.1 Task-oriented everyday gesturesInteracting with everyday objects is a daily routine for mostof us. Simple noncommunicative task-oriented hand ges-tures such as reaching, grasping, placing, and pushing comenatural to us without a conscious effort. DrumTop capital-izes on these gestures to engage players in musical activities.The players are capable of interacting with the interface ifthey are able to interact with everyday objects in a waythey normally do in their daily life. As depicted in Figure3, the basic gestures to play with DrumTop are adaptablefrom the gestures most of us already employ in our daily lifeincluding finding and grabbing objects, placing and pushingthem on the DrumTop tabletop surface to program drum

Figure 2: Beatbox (Left) and Duper/Looper(Right). Modular tangible drum machines that canbe atteched to or placed on top of found objects.Drum Patterns are programmable by rhythmicallytapping on a button on the knocking device (Beat-box) or knocking on the object on which the devicesits (Duper/Looper).

patterns, and rearranging the objects on the tabletop sur-face to make changes to sound patterns.

Tempo control with potentiometer

LED Indicator

Transducer with FSR underneath it

1. Find an object

2. Place an object and push on a transducer to program a drum pattern

3. Explore sounds byrearranging, stacking,or damping objects

Figure 3: The DrumTop basic interaction model andbuilding blocks.

3.2 FeedbackIn DrumTop, everyday objects are the primary feedbacksource of sound, tactile, and visual experience: the playershear the sound directly coming out from the objects; theytouch the objects to feel the sound and change the acousticproperties of the objects; and they see the objects buzzingcaused by a hit from the transducers. The coupling of thesound generation system and the physical interface withwhich the players interact, often missing in digital musicalinstruments [16], offers immediate feedback to the playersof DrumTop, leading to a creative, intuitive, and playfulinteractive musical experience.

3.3 Rapid sound exploration

In the design of DrumTop, special attention has been paidto the physical object’s manipulability to ensure that theplayers can quickly rearrange objects on the tabletop sur-face and program rhythmic patterns. While DrumTop isdesigned to be a step sequencer, its interface design bor-rows that of traditional electronic percussion pads with anintent to make hands-on manipulation of the physical objectand sound associated with that object intuitive. DrumTopis capable of giving voice to everyday objects, and we havetried various materials ranging from paperclip boxes, metaldisks, mobile phones, and plastic toy balls. With the com-bination of appropriate objects, the players can also createsimple melodic patterns that may not necessarily follow thetraditional western musical scale. Therefore, the potentialfor creating a new sound combination is in the hands of theplayers; the creative expressions of the players are stimu-lated from what they find around them and how they decideto play and combine everyday objects.

4. IMPLEMENTATIONDrumTop was designed to be relatively low-cost, simple,and robust. The tabletop interface consists of a 2x4 arrayof circular pads. Within each pad, a transducer, an au-dio exciter from HiWave Technologies [9], equipped with aforce sensitive resistor underneath it is placed flat, facingup, at the center. The eight pads represents a measure inmusical structure. Each pad represents one eighth note ina measure of music. An Arduino board [1], a platform ofDrumTop hardware and software implementation, steps andloops through each pad in a sequence creating an eight beatsper measure structure. As the loop continues, LEDs nextto each pad indicate which pad is currently being activated.

Figure 4: A force sensitive resistor under a trans-ducer for detecting pushing input from the players.An LED indicator at the top of a pad signals playersthat the pad is currently activated.

4.1 Programming drum patternsAs the players place physical objects on the circular padsand press on the transducers, force sensitive resistors un-derneath the transducers signals the Arduino board that apush from the players has been communicated. A prepro-grammed drum pattern immediately loads from the boardmemory, producing a unique hit pattern each time the trans-ducers are pressed. The transducers are operated with dig-ital output pins from the Arduino board to produce a shortimpulse. When the impulse is transmitted to the physi-cal objects, they produce sounds with their unique acoustic

properties.

4.2 TempoAt the center of the tabletop surface, a potentiometer isplaced to control the tempo of the step sequencer. Theplayers change tempo at will by twisting the potentiometerknob, and the visual feedback of an LED sequence helps an-chor players in their beat making and provides a consistentindication of the current tempo.

5. PRELIMINARY FEEDBACK5.1 The interface and player’s feedbackBased on our preliminary demonstration, people tend totake DrumTop as a surprise and quickly understand thebasic concept of the system. By the time players constructa basic rhythm pattern, they are usually smiling and seemto enjoy the whole creative experience. DrumTop seems tostimulate players’ curiosity with everyday objects and theirsound as the most common action players take with Drum-Top was to look in their pockets or around them to explorethe sound of different objects on DrumTop. One player eventook out a wallet from his pocket to place all his cards andmoney on DrumTop to experiment with sounds by stackingand rearranging them. DrumTop also appears to stir collab-oration among players as players discussed about, shared,and agreed upon objects that would go on top of the in-terface as they enjoy themselves with DrumTop. These areexactly the type of exploratory interactions what we hopedto bring out from the players with DrumTop.

5.2 Musical control and variationsThe mechanism for programming drum patterns was ob-scure to most players; most people expected to hear a soundwhen they placed an object on one of pads not thinkingthat they had to press on the pads to cause a sound. Weoften needed to demonstrate how to program drum pat-terns before the trial. After having used the system for afew minutes, most players could predict that rhythm pat-terns on each pad would change according to their pushinputs on the transducers but they did not necessarily havethe understanding of how the patterns changed every timetransducers were pressed. After the initial learning curve,people were able to control the interface at will and theyreported that the interface of DrumTop was easy to under-stand and learn. While most players enjoyed the experiencewith DrumTop, some felt that DrumTop interface should bemuch bigger in size to accommodate bigger objects such asbuckets, guitars, and chairs. Others commented that thesequence of the transducer activation should not loop ina left-to-right order but rather in a circular form. Someplayers also suggested that they want more musical controlthan what the current DrumTop prototype offers, such asto replace the drum pattern programming interface witha computer graphics based interface, to increase the num-ber of pads on the interface, or to add a sequencer bankto progressively record and play back user defined rhythmpatterns.

6. FUTURE WORKOur future plan is to conduct a formal study to evaluateDrumTop as a tool to teach and perform music. The feed-back from players suggests that children and musical noviceswould see DrumTop as an accessible and playful way tolearn musical patterns, and that DrumTop can be used as atool for music performers and artists for collaboration andinteractive performance. Tina Blaine and Sidney Fels sug-gest that the opportunities for social interaction and collab-

oration among participants through collaborative musicalinstruments can create an engaging musical experience fornovices [2]. We believe that encouraging players to collab-orate can further enhance the creative musical experience.

With respect to the design of the interface, one approachtowards enhanced collaborative experience is to physicallyseparate the pads on the tabletop surface while maintainingthe link between the pads through a wireless communica-tion system (Figure 5), making the system modular andportable. Modularizing the system would allow players tobe more flexible in how they play DrumTop. For example,the players reconfigure the position of pads to any arrange-ments that they desired. The design would keep the com-plexity of the interface simple but would add more varietyto the type of musical interactions that novices could create.

Circular Mode Traditional Mode Distributed Mode

Figure 5: Conceptual ideas of the future implemen-tation of DrumTop. The players can reconfigurethe pads in any position, making collaboration withothers easier than current design.

7. CONCLUSIONWe presented a tangible step sequencer that transforms ev-eryday objects into percussive musical instruments. Our in-tention was to create a simple physical interface that givesvoice to everyday objects, afford self-expression and im-mediate engagement for novices, and encourage novices torediscover their surroundings through musical interactionswith everyday objects. DrumTop adapts everyday task-oriented gestures with everyday objects as the basis of musi-cal interaction, allowing novices to freely explore sounds andcombinations of sounds with everyday objects. As playersexplore the musical potentiality of everyday objects, Drum-Top provide sound, tactile, and visual feedback throughthose objects.

Priliminary feedback from players indicate that Drum-Top can be used to explore musical structures and the in-teractions among different objects, sounds, and patterns.DrumTop can be an accessible and playful tool for childrenand musical novices to learn music, and that it can be arich tool for collaboration and music performance. We willcontinue to evaluate DrumTop as a tool to explore teachingand performing music.

8. ACKNOWLEDGMENTSThe author would like to acknowledge the support frommany people to this project including Tod Machover andcolleagues of the Opera of the Future group at the MIT Me-dia Lab. The author would also like to acknowledge the sug-gestions made to this project from Joseph A. Paradiso andNan-Wei Gong from the Responsive Environments group atthe MIT Media Lab.

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