Baumann provides an analytical framework for the various aspects that generate meaningful connections in interface performances. The book’s four chapters are devoted to the author’s practical experience with how music is localized and contextualized from the “creative potential of the abstract vocal terrain” (p. 10) through low- to high-level languages and interface configurations. Processes via human-computer interaction (HCI) tools such as Universal Audio Apollo Twin MKII and Audient iD44, as well as the related emergence of visual programming languages such as PatchWork and its successors OpenMusic, have significantly increased the creative potential of computer-aided composition environments in the last 40 years [1]. An “aural copy” (Alex Nowitz, 2019) derived from these creative practices between humans and computers in live gestural musical performance makes it possible to understand the embodied relationships of musicians with sensors, as well as the “resulting sounds” expressed first and foremost through the experience of HCI. The book’s methodology is based on interviews with artists, nontraditional academic sources, and cognitive suggestions that Baumann captures from her life experiences with music.

The soundscape is amplified, exaggerated by the HCI return to the kinesthetic feel of the performers, while the spatialization is colonized by the creation of independent clones expanding the singer’s body and vocal identities. Baumann’s interest in sensor babbling, that is, the phase in the life of robots when they explore their sensing ability, is transmitted, for example, to nonhuman environmental sounds such as a cargo train “shunted on the tracks at night at the railway station” (p. 14) next to her house, to translate it into vocal phenomena.

The first question posed in the book, then, is whether musical audiences will grasp the subtle nuances of Class-A technology among composers who may be human agents, expert/novice programmers, expert/novice musicians, or even “artificial autonomous agents based on machine learning and machine listening” [2]. Chapter 2, “The Embodied Voice,” shows how this shift toward sonic materiality is affected by various bodily factors, such as posture, breathing, and tension. Denis Smalley, one of the most influential analysts of electroacoustic music, in collaboration with musicologist Pierre Schaeffer, coined the term “spectromorphology” (1986), a descriptive tool based on auditory perception that is intended to aid listening and seeks to help explain “the interplay between sound spectra (spectro-) and how they change and shape over time (-morphology)” (p. 17).

The second question posed in the book asks for hints on the nonlinearity of the body-brain system, and whether evolutionary algorithms (EAs) [3] can handcraft sensory configurations that qualitatively enhance interfaces.

In chapter 4, “Embodied Interface Performance with Gestural Systems,” the author presents a “dynamic framework for creating meaningful interactions between the embodied voice and the disembodied voice through gestural systems.” In the case of singers with gestural systems, they use multiple “proprioceptive perceptions” to navigate their interaction with a machine or computer system, which involves the use of physical gestures to control or manipulate sounds. These proprioceptive perceptions can include the sensation of muscle tension, joint position, and changes in force or pressure. For example, grasping an object and feeling its properties (shape, texture, weight, and so on) requires integrating information from the tactile and kinesthetic senses [4]. Haptic feedback is an important aspect of HCI because it provides users with a sense of touch and feel when interacting with a computer system. As in the example of Liquid Souls, a vocal performance project by Baumann in 2011, emotional improvisations by HCI helped singers overcome linguistic boundaries, allowing for hybrid musical material between meaning and sound. Finding principles of expressiveness in musicians’ performances means that analysts need to find a “state space,” a term coined in the early 1960s for a phase space, corresponding to the German word zustandsraum. Sonic space blends with gestures, and the movements produce a musical action insofar as the listener manages to perceive the musical production of the performer (pp. 71-72), confirming that the musical gestures reflect aspects of the neurological emotional responses [5].

Baumann does not answer all questions about instrumental gestures, meta-gestures, geometric movements, or their choreographic combination, because designing embodied scenarios with sensor interfaces is a metaphor we can draw on for clarifying, classifying, and expanding our gestural vocabulary, even if body images remain captured in an “ambisonic three-dimensional space” (p. 75). The author represents herself as a dissolved identity, hating the unknown to her and schizophrenically layering this resultant disembodied vocal terrain that she can shape and interact with through the help of gestural systems. These are pads creating a mixture of acoustic vocals and live electronics, and as in all textures seeping in, are fluid, in counterpoint to imaginary phenomena, embraced by surrounding mystical technology capable of resembling the myth of Narcissus and Echo (p. 32): an illusory alienating repetition of the self, with no apparent hope of communication, where only the flow of events can change doors and find the exit.