Rodrigo F. Cádiz

Volume visualization using a spatially aware mobile display device

Volume visualization is a difficult three-dimensional task and a significant amount of research is devoted to the development of a suitable computer input device for it. Most of the proposed models use fixed displays, thus rendering extracted slices in orientations unrelated to their real locations within the volume. We present a new device which takes a different approach, as it leaves the volume in a fixed location and demands the user to change his or her posture to explore it from different angles. To implement this, we built a prototype based on a mobile display equipped with sensors that allows it to track its position, which is related to the location of the slice plane within the volume. Therefore, the user can manipulate this plane by displacing and rotating the display, which is a very intuitive method with minimum learning time. Furthermore, the postural changes required to use the device add a new channel of feedback, which effectively helps to reduce the cognitive load imposed on the user. We built a prototype device and tested it with two groups of volunteers who were asked to use it in a medical imaging application. Statistical analysis of the results shows that explorations made with the proposed device were considerably faster with no penalty in precision. We believe that, with further work, the proposed device can be developed into an useful tool for radiology and neurosurgery.

Designing a Musical Instrument: Enlivening Theory Through Practice-Based Research

Introduction The Arcontinuo is an electronic musical instrument that was conceived with the intention of overcoming the difficulties of other instruments that have failed in getting a consistent place in the musical scene. Its creation was based on a model founded in concepts of interaction design research and narrative identity that we intend to describe in detail in the first part of this article. This model, we hope, could be applied to any design research process providing an approach to creating products, services and experiences with a quality rooted in the personal and collective organization of meaning. The second part of the article explains the implementation of the model as a case study, the Arcontinuo.

Sound synthesis with auditory distortion products

This article describes methods of sound synthesis based on auditory distortion products, often called combination tones. In 1856, Helmholtz was the first to identify sum and difference tones as products of auditory distortion. Today this phenomenon is well studied in the context of otoacoustic emissions, and the “distortion” is understood as a product of what is termed the cochlear amplifier. These tones have had a rich history in the music of improvisers and drone artists. Until now, the use of distortion tones in technological music has largely been rudimentary and dependent on very high amplitudes in order for the distortion products to be heard by audiences. Discussed here are synthesis methods to render these tones more easily audible and lend them the dynamic properties of traditional acoustic sound, thus making auditory distortion a practical domain for sound synthesis. An adaptation of single-sideband synthesis is particularly effective for capturing the dynamic properties of audio inputs in real time. Also presented is an analytic solution for matching up to four harmonics of a target spectrum. Most interestingly, the spatial imagery produced by these techniques is very distinctive, and over loudspeakers the normal assumptions of spatial hearing do not apply. Audio examples are provided that illustrate the discussion.

Wheels Within Wheels: Brain-Computer Interfaces as Tools for Artistic Practice as Research

Practice as research (PaR) is concerned with practice both as a method for inquiry and as evidence of the research process, producing embodied knowledge. It has been proposed that it is the foundational strategy in performative research, a kind of research apart from quantitative and qualitative research, characterized by being expressed using forms of symbolic data different from quantities or words in discursive texts. In this context, practice requires constant reflection upon itself to yield insights that can be used in a never-ending loop of creation. As practice is performed by the body and produces embodied knowledge, tools that allow querying the body during the artistic process may provide information that supports this creation/reflection loop. Previous artistic BCI applications have shown that they are suited to work as introspection tools (affective states, correlation between performed actions and area activations), as the source of raw material to be used in the creative process (raw signal, patterns of activation, band power), and as controllers for artistic instruments. We believe that previous research has laid the groundwork for the use of BCIs as tools in PaR. In this paper, we propose a framework for this and review three examples of previous artistic work using BCIs that illustrate different aspects of said framework.

Sound synthesis of a gaussian quantum particle in an infinite square well

This article describes a synthesis technique based on the sonification of the dynamic behavior of a quantum particle enclosed in an infinite square well. More specifically, we sonify the momentum distribution of a one-dimensional Gaussian bouncing wave packet model. We have chosen this particular case because of its relative simplicity and interesting dynamic behavior, which makes it suitable for a novel sonification mapping that can be applied to standard synthesis techniques, resulting in the generation of appealing sounds. In addition, this sonification might provide useful insight into the behavior of the quantum particle. In particular, this model exhibits quantum revivals, minimizes uncertainty, and exhibits similarities to the case of a classical bouncing ball. The proposed model has been implemented in real time in both the Max/MSP and the Pure Data environments. The algorithm is based on concepts of additive synthesis where each oscillator describes the eigenfunctions that characterize the state evolution of the wave packet. We also provide an analysis of the sounds produced by the model from both a physical and a perceptual point of view.

Creación musical en la era postdigital

In this article, some of the most important features and challenges of musical creation in the post-digital era are discussed, from the particular viewpoint of a composer. Three areas of musical creation are given special consideration: electroacoustic music, algorithmic composition and new interfaces for musical ex - pression. This article presents both theoretical discussions and examples taken from the authors artistic production.

Understanding the Quality of Subject–Object Interaction: A Disciplinary Model for Design Validation

Abstract A disciplinary model is proposed for design validation (DV), which contemplates validation as a process that uses quantitative and qualitative evidence to confirm that products, services, or other objects have enough interaction quality to create a valuable satisfaction level. Our model is based in the subject–object interaction event in order to analyse perceived value. We conceptualize quality as an emergent property from that interaction event, when there is a flowing process between personal meaning and value, projected on the object. This is an advantageous point of view to understand how much, why and in what way designed objects are invested with value, in order to carry out strategic decisions.