Localising Borders

Sound installation / performance with directional audio and lasers exploring echolocation



Sound is generally assumed to diffuse and fill an environment and be omnidirectional. Light is assumed to travel in a straight line and be more amenable to being directed such as in a laser or even a torch or a spotlight. We may not be able to see around a corner but we can hear around a corner. Ultrasound provides one means by which sound can be more directional and behave more similarly to how we imagine light to be, allowing us almost to “see” via sound.

In Localising Borders, a set of parametric speakers and a laser are arranged with the sound and the light pointing in the same direction. The parametric speakers emit modulated ultrasound which is highly directional, creating a “beam” of sound more similar to light than conventional audio. The sound remains inaudible until it is reflected off an object such as a wall or a person at which point it is demodulated and sound appears to be emitted from the reflecting object. The point at which the sound is reflected (and is illuminated by the laser) marks out the interiors of the space in a process known as echolocation and used in sonar. The sound played are based on recordings of ultrasonic bat calls used for such purposes which have been transposed to the audible range of human hearing.

The work has also been presented as a performance, with the direction of the speakers and the laser being controlled by a performer.

What is it like to be a bat? Thomas Nagel asks in his seminal essay, and posits the difficulties faced by non-bats in answering this question. Without necessarily providing an answer, Localising Borders attempts to present an alternative way of listening or perceiving sound.

Ultrasound provides additional uses in which sound is no longer a privileged domain of our ears. It has been used in medicine for therapeutic purposes due to its less invasive nature. It is also useful in diagnoses such as through imaging, and in communication. Furthermore, the possibilities for haptic feedback and levitation of objects have been demonstrated in recent years. As well as its benefits, safety issues arise. Ethical concerns also become apparent in recent experimental uses including its application on the brain. Moreover, the development of directional audio parallels that of the increasing use of sonic weapons by the military and law enforcement which is of concern.

Commissioned for the exhbition “Grenzen des Verstandes (Borders of Understanding)” at NEXTEX, St Gallen, curated by Kasia Maksymowicz.
With support from Asia Culture Institute / Asia Culture Center.