How can we re-empower opera singers, extending their control over accompaniment and vocal expressivity? To answer this question, I have opened a novel design space, Extending Opera, consisting of interactive artist–operated tools to be used on-stage. The research has its methodological groundings in Research through Design (RtD) and Research through the Arts (RttA). This particular method is coined "research-throughthe- art-form-opera" – as I have worked within the realms and traditions of opera, probing its boundaries by designing, researching and creating through its own artistic toolbox.

Originally conceived for personal use, the artifacts were later used by other singers and incorporated in performances of opera in small and large scale. By composing and designing for the requirements in operatic productions, high demands on robustness were explored in and through custom-built interfaces.

The work resulted in ten novel artifacts and performances exploring the expressivity of these tools. Extending Opera is guided by and probed through three questions:

1. How can the design and creation of interactive, artist-operated instruments be informed by deep musical knowledge and be probed by the particular conditions surrounding an operatic production?

2. What impact can interactive, artist-operated instruments have on the opera singers themselves and on their vocal technique?

3. How can interactive, artist-operated instruments empower opera singers, thus challenging contemporary power hierarchies – thereby reconnecting to the explorative practice in opera's early days?

My knowledge contribution has surfaced through artistic practice and consists of the exemplars and the artworks, as well as three abstractions – one procedure, one requirement and one experiential quality.

Sensory Digital Intonation highlights how the fine-tuning of technologies and real-time interactivity is incorporated in a feed-back loop with artistic concerns and creativity.

Performative Stamina ("The Premiere-Factor") highlights how the traditional procedures leading up to a premiere in opera influence the demands on robustness and reliability within the components and the overall design of the novel artifacts.

Vocal Embodiment is an experiential quality that describes how the interactive artifacts change the singing itself.

In the conclusion, Artistic Re–Empowerment is discussed, proposing that power structures in opera have been probed through the use of the novel artist-operated interactive instruments.

This thesis collects and contextualizes several projects involving artistically directed prototyping where new artifacts have been developed, in multi-disciplinary groups of practitioners, for use in performance contexts. These projects and their resulting publications have been team efforts, and therefore all papers have more than one author. In the introduction, a complementary perspective to that of the publications is offered, engaging with the characteristics of the digital innards of these artifacts and their digital material qualities. The stance that software source code is a design material is argued, and the notion of the crafting coder is used to view processes that use code as material for artistic creation. Code is also prominently featured in the introductory chapter with examples of some of the central components of the sound processing techniques that have been successfully used in the projects described in this thesis.

The artifacts that are described in the thesis are: The Throat, an instrument for augmenting the singing voice using gestural control in real-time, The Vocal Chorder, a string based instrument using full-body interaction that also allows for audience participation through an installation mode, The Charged Room, a video tracking installation that lets users manipulate sound by moving across a stage, and Nebula, a garment that senses the users movements and responds with sound. These artifacts have been evaluated in the context they are designed for, and not only tested in laboratory settings, to make sure that the knowledge produced is valid. Several performances and peda-gogical courses have been used as empirical foundation for the claims of empowerment, expressivity, and performance qualities ascribed to the developed artifacts.