Cassette Locale is an installation that uses hypersonic sound. It was commissioned by Botkyrka Konsthall for an original 8-channel guitar composition by musician Derek Gripper. Hypersonic sound travels in a narrow beam that can be tightly focused like a beam of light (fig. 2). In this installation, eight Holosonic Audio Spotlight panels are arrayed, each directing the sound of a single musical instrument  towards a central point in space (figs. 3, 4). Visitors pass along and across individual sound beams on the edge of the array, and drawn by sonic cues of increasing complexity, move towards a centralized zone of overlapping beams where the full ensemble is heard (figs. 9-13).

Given the primacy of the visual world, we asked: To what extent might sound drive behavior?

Unlike conventional speakers that vibrate a diaphragm to amplify sound, Holosonic audio panels use transducers to concentrate and direct acoustic energy. The source of sound is not the physical device itself, but rather air, the medium ultrasonic waves travel through. Ultrasound frequencies are completely inaudible, far outside the range of human hearing (figs. 5, 6). Algorithms act on air’s non-linear properties, inducing inaudible ultrasonic waves to generate new audible frequencies (refs. 1-5).

The technique of using nonlinear interactions of high-frequency waves to produce low-frequency waves was developed in the 1960s for the United States Defense Force for underwater sonar application. By 1975 these nonlinear effects were demonstrated to occur in air as well, and long-range acoustic devices (LRADs) were employed for ship-to-ship communication over large distances. The capacity to project sound up to 149 decibels beyond 2,000 meters led to the adaptation of this communication device into a psychoacoustic weapon for military deployment. At this decibel range LRADs cause immediate headaches, disabling pain and in some instances, hearing loss.

Since the 1990s the United States Department of Defense’s ‘1033 Program’ has transferred more than $7.5 billion worth of surplus military equipment to local police departments at little or no cost. Evidence of this widespread militarization of America’s police force – including the use of the LRAD 100X ‘sound cannon’ on crowds of protesters – has become apparent in U.S. cities over the past decade.

In the summer of 2014 Michael Brown, an unarmed Black teenager, was shot and killed by a police officer in Ferguson, Missouri. Brown’s murder came after the acquittal of the killer of another Black teenager Trayvon Martin in Florida, and the murder of Eric Garner by New York City police officers . Protests erupted in Ferguson and quickly spread across the United States. During the ensuing unrest local police departments used an arsenal of crowd-control weapons on unarmed protesters.

That summer, the technology used to produce this contemplative soundscape in the tranquil Serra dei Giardini in Venice was simultaneously deployed in psychoacoustic weapons against peaceful protesters on the streets of U.S. cities.