Gelineck, Steven

Serafin, Stefania

English

This paper presents the development of a set of musical instruments, which are based on known physical modeling sound synthesis techniques. The instruments are modular, meaning that they can be combined in various ways. This makes it possible to experiment with physical interaction and sonic exploration, thereby possibly extending the potential of the physical models

    Aalborg UniversitetPhysical Modeling Modular Boxes: PHOXESGelineck, Steven; Serafin, StefaniaPublished in:The fifth International Workshop on Haptic and Audio Interaction Design (HAID)Publication date:2010Document VersionEarly version, also known as pre-printLink to publication from Aalborg UniversityCitation for published version (APA):Gelineck, S., & Serafin, S. (2010). Physical Modeling Modular Boxes: PHOXES. In The fifth InternationalWorkshop on Haptic and Audio Interaction Design (HAID) Aalborg Universitetsforlag.http://media.aau.dk/~stg/phoxesGeneral rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright ownersand it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.            ? 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You may freely distribute the URL identifying the publication in the public portal ?Take down policyIf you believe that this document breaches copyright please contact us at vbn@aub.aau.dk providing details, and we will remove access tothe work immediately and investigate your claim.Downloaded from vbn.aau.dk on: November 29, 2020Physical Modeling Modular Boxes: PHOXESSteven GelineckAalborg University Copenhagen, Department of Architecture, Design and Media TechnologyLautrupvang 15, DK-2750stg@media.aau.dkStefania SerafinAalborg University Copenhagen, Department of Architecture, Design and Media TechnologyLautrupvang 15, DK-2750sts@media.aau.dkABSTRACTThis  paper  presents  the  development  of  a  set  of  musical instruments, which are based on known physical modeling sound synthesis techniques.  The instruments are modular, meaning that they can be combined in various ways. This makes it  possible to experiment  with physical  interaction and  sonic  exploration,  thereby  possibly  extending  the potential of the physical models.  Author KeywordsPhysical  Modeling,  Physical  Interfaces,  Musical Instruments,  Exploration, Creativity, Electronic Music.ACM Classification KeywordsH5.5. Sound and Music Computing: Modeling. H.5.2 User Interfaces:  Input  devices  and  strategies.  H.1.2 User/Machine Systems: Human Factors. INTRODUCTIONThe PHOXES modular instruments have been developed in order to investigate what happens when physical modeling sound  synthesis  algorithms  are  controlled  in  an environment, which encourages creativity and exploration. The physical control of the models plays a large part in how the sonic potential of the models is perceived – on both a lower  level  (e.g.  which  physical  gesture  must  the  user perform to excite a certain model?) and on a higher level (e.g. how do different control structures  let  users explore the sonic potential of the models?).In order to investigate the impact of the higher level control structures a set of modular electronic instruments have been developed. The goal has been to extend the creative use of physical  modeling  sound  synthesis  by  focusing  on exploration.  The  HCI  research  area  that  deals  with creativity support tools suggests that in order to support the kind of  exploration that  is  crucial  for  creative work, one must design for low threshold, high ceiling, and wide walls [1]. In other words there must be a balance between how intuitive the system is (low threshold),  how  powerful it is (high  ceiling) and  how  well  it  encourages  exploration, letting  users  keep  finding  new ways  of  combining  /con-trolling elements or movements (wide walls).  The proposed system tries to balance the intuitive causality inherent in the physical modeling technique with a flexible exploratory  system  that  provides  freedom  within  the boundaries of the individual elements (each PHOX acts as an instrument on its own and is naturally constrained, but because they can be combined in a modular fashion, they also provide the sense of freedom).PHOXES MODULAR SYSTEMAt present time four PHOXES have been developed: tube PHOX, particle PHOX, friction PHOX, and drum PHOX. Each  PHOX  implements  a  different  physical  model  and consists  of  a  unique  excitation  controller,  intended  to naturally relate to that model. For instance, the tube PHOX implements  a  physical  model  of  a  tube  and  a  flute-like excitation  controller.  Each  PHOX  also  consists  of  four knobs  for  adjusting  model  parameters,  three  buttons  for controlling  the  mapping  involved  in  combining  the PHOXES  and  an  LCD  screen  for  displaying  mapping settings. We felt that it was important that all input/output functionality  was  built  into  the  PHOXES  themselves  so focus  could  remain  solely  on  the  instruments  while exploring them (as apposed to also focussing on controlling some parts using a laptop). The physical models are written as Max/MSP1 externals and the system is developed in the Max/MSP environment. The idea is  that the PHOXES are powered through Max/MSP but  the sound is  rewired to for  instance  Ableton Live  or Logic so eventual test subjects can explore the PHOXES' potential in a familiar environment. Inputs and outputs from the  PHOXES  are  handled  by  a  PhidgetTextLCD  with PhidgetInterfaceKit  8/8/82 embedded  in  each  of  the 1 a graphical programming language (http://cycling74.com/) 2 from http://phidgets.com1Figure 1. The PHOXES send control data through USB to Max/MSP, which is rewired to the DAW of your choice – e.g.Ableton Live.PHOXES - See Figure 1 for an overview of the system.Physical ModelsThe physical models which have been implemented present a variety in complexity, sonic fidelity, and physicality (the type  of  excitation  gesture  they  naturally  propose).  The physical models used are:• tube PHOX – turbulence model based on [2]. • particle  PHOX –  particle  model  based  on Physically Informed Sonic Modeling (PhISM) [3]. • friction  PHOX –  friction  model  based  on  the elasto-plastic friction model [4].• drum  PHOX –  drum  model  based  on  2D waveguides [5].Excitation ControllersEach PHOX implements a physical controller, used to exert energy into the model. The controllers have been chosen to naturally  extend the  physical  models  they  by default  are connected to. The modularity of the PHOXES system then lets the user play around with exciting any of the physical models  using  any  of  the  excitation  controllers  from  the different PHOXES.The excitation  controllers  used  are  listed below, together with the excitation gestures that they afford. They are all used to measure velocity, which is mapped to the amount of energy injected into the system. • tube  PHOX –  flute  controller  implementing  an amplified low pressure sensor (1INCH-D-4V from All  Sensors).  The  user  blows  into  a  small  tube attached to the sensor, which senses how hard the user blows, giving the user the feeling of blowing into something similar to a recorder. • particle  PHOX – crank attached to a multi-turn rotational potentiometer (Model 357 from Vishay). The user  turns the crank to produce energy. The rotational  speed  is  measured  and  used  as excitation. The crank gives the user the capability of  experimenting  with  both  continuous  and instantaneous excitation gestures. • friction PHOX –  friction  slider  implementing  a ribbon sensor (SoftPot from Spectra Symbol). The sensor lets the user slide a finger back and forth on a horizontal flat surface. The velocity of the back and forth sliding gesture is measured and used as excitation.  • drum PHOX – two drum triggers implementing piezo transducers  (PSG100 from Kingstate).  The drum triggers detect the occurrence of a hit (finger tapping gesture) and the velocity of that hit.ModularityTwo or more PHOXES can be combined by choosing how energy is put into any given PHOX. Energy can either come from an excitation controller (it is possible to use any of the available excitation controllers embedded in the PHOXES to control any of the physical models), or it can come from the sound produced by a different PHOX – similar to [6], where sound is used to drive the excitation mechanism of the physical models. This means that there are a couple of challenges when developing the physical models. Each of the  models  must  1)  be  able  to  respond  to  energy  from different  types  of  excitation  gestures  (continuous  or instantaneous [7]) and 2) have a way of mapping sound to input energy. When  each  PHOX  is  played  on  its  own  using  its  own excitation controller  there is a natural mapping metaphor, which makes the relationship between gesture  and sound intuitive and natural (for instance making squeaky friction sounds by sliding your finger  back and forth,  or  making flute sounds by blowing into a tube). But the naturalness of the metaphors change when an excitation controller  from one  PHOX  is  used  to  excite  a  physical  model  from  a different PHOX (when for instance using a crank to make flute sounds or when blowing a drum). Although unnatural, it  seems  that  the  mapping  is  still  perceived  as  being intuitive. Because of the nature of physical modeling there is  a  natural  causality  relationship between the amount  of energy you put in and the sound you get out. If the amount of  energy  does not  change (only the gesture one uses  to produce that energy changes), we believe that the mapping is  intuitive.  By  presenting  the  user  with  a  variety  of physical gestures for controlling the same physical model, we open up for a physical, more embodied exploration of the sonic potential of the models.Goto  http://media.aau.dk/~stg/phoxes/ for details  about  mapping,  videos,  pictures  and  additional development information.CURRENT STATE AND FUTURE DEVELOPMENTAn  early  pre-test  was  conducted  where  an  experienced electronic musician borrowed the PHOXES for a duration of 10 days – see Figure 2. The goals were 1) to get a first impression of how well the system encouraged exploration and  whether  the  system  was  creatively  inspiring  and motivating, 2) to explore the evaluation methods involved in testing such a complex set of instruments in as natural an environment  as  possible,  and  3)  to  see  if  the  build  and functionality of the PHOXES would withhold such a long test  period without our interference. Further details  about the test can be found in [8]. The early impressions have shown that in order for future test subjects to be able to use the PHOXES in their natural working environment  (where they integrate them in their normal setup with mixers, effect-racks, other controllers, computer running their favored DAW, etc.) improvements should be made to the efficiency of the code. Some of the synthesis models are quite computationally expensive and are currently run on the test subject's own computer. This means  that  it  is  not  possible  to  run  large  DSP-heavy projects at the same time as playing the PHOXES. This puts an undesirable limit to the potential use of the PHOXES. We want the test  subjects to be able to work on projects exactly the way they are used to, in order to see how the PHOXES integrate in a natural environment. Another issue was that the test subject did not get to explore parts of the modular system. This might have had to do with the  mapping  functionality  being  presented  in  an  overly complicated way or because the test  period was not long enough,  and  the  test  subject  simply  did  not  get  to  some parts.The pre-test  also showed that  the test  subject was highly motivated and stimulated by the PHOXES. He especially noted the balance between the familiar form factor of the instruments (familiar to an electronic musician, that is) and the naturalness of the physical interaction. It made him feel like  he  was  playing  an  acoustical  instrument,  but  in  an electronic  music  setting.  He  found  the  PHOXES  very durable and easy to set up. He found the physicality of the controls very inspiring and lastly he said that  the sounds they made were amazing. Before  conducting  a  larger  scale  longitudinal  evaluation with more test subjects, improvements will be made to the PHOXES regarding computation and in  the way that  the combination mapping is controlled. Hopefully the large scale evaluation can tell us if the success of the pre-test was a matter of novelty alone, or if developing for this kind of physical exploration does in fact improve the creative use of physical modeling sound synthesis.REFERENCES1. B. Shneiderman, G. Fischer, M. Czerwinski, M. Resnick, B. A. Myers, L. Candy, E. A. Edmonds, M. Eisenberg, E. Giaccardi, T. T. Hewett, P. Jennings, B. Kules, K. Nakakoji, J. F. Nunamaker, R. F. Pausch, T. Selker, E. Sylvan, and M. A. Terry, “Creativity support tools: Report from a u.s. national science foundation sponsored workshop,” International Journal of Human Computer Interaction, vol. 20, no. 2, pp. 61–77, 2006.2. P. Cook, “A Meta-Wind-Instrument Physical Model and a Meta-Controller for Real Time Performance Control,” in Proceedings of the International Computer  Music Conference, pp. 273–276, San Francisco, California: International Computer Music Association, 1992.3. P. Cook, “Physically Informed Sonic Modeling (PhISM): Synthesis of Percussive Sounds,” Computer  Music Journal, vol. 21, no. 3, pp. 38–49, 1997.4. F.  Avanzini,  S.  Serafin,  and  D.  Rocchesso, “Modeling interactions between rubbed dry surfaces using an  elasto-plastic  friction  model,”  in  Proceedings of  the  International  Conference  on  Digital  Audio  Effects, (Hamburg), pp. 111–116, DAFX, 2002.5. S.  A.  V.  Duyne  and  J.  O.  Smith,  “Physical modeling  with  the  2-d  digital  waveguide  mesh,”  in Proceedings  of  the  International  Computer  Music  Conference, pp.  40–47,  San  Francisco,  California: International Computer Music Association, 1993.6. S. Gelineck and S. Serafin, “A practical approach towards  an  exploratory  framework  for  physical modeling,” Computer Music Journal, vol. 34, no. 2, 20107. C.  Cadoz,  “Instrumental  Gesture  and  Musical Composition,”  in  Proceedings  of  the  International  Computer  Music  Conference, pp.  1-12,  San  Francisco, California:  International  Computer  Music  Association, 1998.8. S. Gelineck and S. Serafin, “PHOXES – Modular Electronic  Music  Instruments  Based  on  Physical Modeling  Sound Synthesis,”  in  Proceedings  of  the  7th  Sound  and  Music  Computing  Conference,  Barcelona, Spain, 2010.3Figure 2. User playing the PHOXES. Here he is playing the particle PHOX on its own. Energy is exerted into the model by rotating the crank.

Physical Modeling Modular Boxes: PHOXES

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Physical Modeling Modular Boxes: PHOXES

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