Lawrence Abu Hamdan, a 33-year-old Jordanian artist based in Beirut, describes himself as an “ear-witness”—someone who testifies publicly about what he has heard. The word is a twist on the more familiar “eye-witness,” to refer to someone who has seen a crime or accident and reports on it.

In work that bridges conceptual art and crusading documentary journalism, Abu Hamdan shows how the investigation of sound can reveal states of affairs that might otherwise remain hidden. He uses techniques at the cutting edge of technology, and presents the results of his investigations in ways that arouse the conscience and at the same time evoke sensations of strangeness and awe.

Much of his work focuses on issues in Arab countries. His work Earwitness Theater, a multi-media installation now at the Chisenhale Gallery in London until December 9, presents a chilling account of the experiences of prisoners at the notorious Saydnaya prison in Syria.

Saydnaya is one of the prisons the Syrian state uses to punish and break Syrian citizens who have fallen afoul of it, especially since the beginning of the 2011 uprising that led to the continuing civil war. The government prevents access to the prison by journalists, foreign diplomats or non-governmental organizations, and denies that torture and killing take place inside it. In the absence of words or images of the site, Abu Hamdan worked on a project to build a model of the prison using only the memories of what a group of former prisoners heard during their imprisonment.

Abu Hamdan found that prisoners at Saydnaya became acutely aware of the sounds around them. They were often blindfolded and kept in darkness; their awareness of sound was heightened by a rule of silence: prisoners were forbidden to speak to each other, or even to cry out when beaten. They built up three-dimensional acoustic models of the prison in their minds; gradually learning from the sounds they heard when new prisoners were arriving, or when guards were approaching along the corridors. The prisoners could only whisper to each other, a sound that can usually travel only a short distance.

Abu Hamdan said, in an interview with curator Ellen Greig, “In Saydnaya, you cannot speak, you cannot cough, you cannot even move, so silence became this extremely physical thing.” We usually think of silence as something spiritually enriching—silent prayer, for example, or the metaphysical musical ideas of John Cage; in this work, silence is terrifying.

Saydnaya prison is about 30 kilometers north of Damascus. On Google maps, it can be clearly recognized for its tricorn shape. It was built in 1987, on an East German design (a legacy of Ba’thist Syria’s cold war relationships with countries of the former eastern bloc). In ghoulish humor, it has been called the Mercedes Benz of prisons, for its German design and resemblance to the car manufacturer’s three-pointed trademark.

At the Chisenhale exhibit, visitors enter a room that is totally dark inside. Loudspeakers play a sonic collage of prisoners’ voices, translated in a soft voice from Arabic to English; sound effects created to replicate the acoustic surroundings of the prison, and technical statements about the comparative measurement of the intensity of loud and soft sounds. Outside the listening room, the artist has arranged a collection of weirdly mundane objects used in creating the sound effects.

In its most recent annual report, Amnesty International estimated that around 13,000 people have died at Saydnaya prison, “extrajudicially executed in night-time mass hangings between 2011 and 2015.”

Abu Hamdan recorded the memories of former Saydnaya prisoners in collaboration with Amnesty International and with Forensic Architecture, a research group based at Goldsmiths, University of London, where Abu Hamdan got his Ph.D. Forensic Architecture describe their work as “the production and presentation of architectural evidence… on behalf of international prosecutors, human rights organisations and political and environmental justice groups.” Earlier this year, in collaboration with The New York Times, Forensic Architecture used powerful digital techniques to create detailed analyses of destroyed buildings to show how the Syrian regime dropped chemical weapons on residential areas in the city of Douma, disproving claims by Russian and Syrian state media that no such attacks took place.

Like Abu Hamdan, Forensic Architecture’s work straddles the fields of investigative research and art. The group emerged from Department of Visual Cultures at Goldsmiths, University of London, and is one of four finalists for the 2018 Turner Prize, the UK’s most prestigious award for visual art. (Tate Britain, where the shortlisted artists are on display, produced a short video explaining Forensic Architecture’s work.) “We are pathologists of buildings,” said Christina Varvia, the department’s deputy director, in the video. “We read buildings. We read the ruins so we can understand what has taken place. Contemporary warfare is mainly urban. Architects are somehow well positioned to understand what has happened within war.”

The connection between the political and the aesthetic aspects of this work is complex, hard to pin down and impossible to simplify. But certainly the way they present information is new and has a strange beauty—see, for example, Lawrence Abu Hamdan’s work titled “The Freedom of Speech Itself.” These qualities can only help draw attention to the issues they are investigating.