Fig. 1 – Serra dei Giardini during 2014 Venice Architecture Biennale

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?

Fig. 2 – Sound fields of a conventional speaker (left) and a Holosonic Audio Spotlight (right) show the sound isolation capacity of ultrasonic technology. Sound levels are reduced by over 90% with just one step outside the beam.

Fig. 3 – Sound is heard only when the ear aligns with a sonic beam making the experience of the musical score unique to each individual, contingent on a person’s height, speed and path of movement.

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).

Fig. 4 – Serra dei Giardini Installation Site Plan

Fig. 5 – Infrasound monitoring arrays Station IS18 in Thule, Greenland

Fig. 6 – Audio spectrum: infrasound, sound and ultrasound.

Fig. 7 – Long-range acoustic devices (LRADs) were developed for the US Navy in 2000 after the bombing of the USS Cole, enabling clear communication with approaching vessels over 3,000 meters away.

Fig. 8 – LRAD 100X ‘sound cannon’ used by Ontario Provincial Police against protestors during the G20 summit in Toronto in 2010

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.

Fig. 9 – Cassette Locale, x; y; z coordinates (plan location, height and tilt) of each acoustic panel establishes the layout of the sonic landscape and the spatial navigation of the resulting multilayered music score.

Fig. 10 – Height and tilt of an acoustic panel establishes the distance an ultrasonic beam travels. Discrete beams of sound reach people walking outside the Sierra dei Giardini, producing uncanny effects of intimate proximity at a distance.

Fig. 11 – Height and tilt angles of Audio Spotlight panels 4, 5, 6 and 7 direct sound to align with the ear-off-the-ground height of a peripherally walking person and a centrally seated person.

Fig. 12 – Plan diagram of the 8-panel hypersonic array

Fig. 13 – Black Lives Matter demonstration summer 2014, St. Louis. Credit: Joshua Lott/Reuters

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.

Fig. 14 – Serra dei Giardini installation view, summer 2014.


Venice Architecture Biennale Offsite




600 sqf


Sound installation

systems and materials:

Holosonic Audio Spotlight


Botkyrka Konsthall

project team:

Lindy Roy with Aldo Cherdabyev

related projects:

Hotel QT, Deitch Projects: The Garden Party, CCA: Traces of India, Artists Space, Meatspace, The Design Museum: The Peter Saville Show, MoMA P.S.1: Subwave


Fittja Pavilion offsite at the 2014 Venice Architectural Biennale


Rashawn Ray, “How 9/11 helped to militarize American law enforcement” The Brookings Institute (September 9, 2021)


Brian Barton, et al, “Maps of the Auditory Cortex,” Annual Review Neuroscience (2016.39): 385-407


Timothy D. Griffiths, et al, “Navigating the Auditory Scene: An Expert Role for the Hippocampus,” The Journal of Neuroscience 32.35 (August 29, 2012): 1251-1257


Hermann Helmholtz, ‘On the Sensations of Tone’.


David Tank, et al, “Mapping of non-spatial dimension by the hippocampal-entorhinal circuit,” Nature Vol 543 (March 30, 2017)

Ref. 1 - Marine infrasonic wavefield.

Ref. 2 - Distribution of sound frequencies in the human cochlea.

Ref. 3 - Distribution of sound frequencies from the cochlea to the brain.

Ref. 4 - Cochleotopic mapping of sound in the auditory cortex of the human brain..

Ref. 5 - Tonotopic map of sound frequencies shown in Voronoi tessellation.