Three years ago, Lawrence Abu Hamdan spent a week in a room in Istanbul that would transform the way he understood the world. “The things I thought going in and coming out were completely different,” he says. “There was a radical shift. That’s why I made the works I have made.”

Abu Hamdan – 34, neatly bearded, fashionably bespectacled – tells me this in Beirut, where he lives with his wife and daughter. It is a few days before he travels to the UK to install his entry in the Turner prize show in Margate, which will feature the work of three other finalists. We are in an office in the echoing, post-industrial Sfeir-Semler gallery, where many of his works, recent and not-so-recent, are on view until January.

That week in 2016 he was working on a report for Amnesty International, interviewing six survivors from Saydnaya prison, 25km north of Damascus – a nightmarish black hole of abuse and torture, where 13,000 people are estimated to have been killed by Bashar Al-Assad’s regime.

Abu Hamdan’s expertise is sound: he calls himself a “private ear”. He has made work about mishearings that lead to criminal cases, and about lie-detector technology. He was asking the survivors specifically about what they had heard in the prison. “The only way we can access much information about the site is through acoustic memories,” he says, “because people were blindfolded when they came in and held in darkness.”

Reverberations … Lawrence Abu Hamdan’s installation at the Turner Contemporary. Photograph: Stuart Leech

Abu Hamdan was working alongside Forensic Architecture, an agency that uses architectural skills to investigate human rights abuses. (It was nominated for the Turner prize last year.) Working with an architect, Abu Hamdan used the BBC and Warner Bros sound-effect libraries as prompts to help the witnesses summon up the sounds of, for example, doors shutting, locks turning and water dripping.

There were more terrible noises to recall, too. When someone was being beaten with a length of pipe, you could hear it, as the sounds reverberated around the building. At the same time, the prisoners were forced into silence on pain of execution: this was silence as a weapon. The inmates’ hearing became so acute they could pick out the softest noises: the minute crack of lice being killed was like a sesame seed being crushed, said one witness.

Inmates hearing became so acute they could pick out the softest noises: the minute crack of lice being killed

Crucially, the sound memories allowed Abu Hamdan and his colleague to build a picture of the prison, which they translated into a piece of 3D imaging that forms the centrepiece of the Amnesty report. “One prisoner had memorised how each lock sounded,” says Abu Hamdan. “So he knew how many doors there were. Initially, that was a survival thing: he had to know where the guards were. But it helped us understand how many cells were in use. You could start corroborating it with other information to estimate how many people there were in the prison.”

The report did much to shed light on this dark and terrible place. But for Abu Hamdan, it did not and could not end there. “It changed the way I thought about memory, about architecture, about testimony, about language and the human voice,” he says. Part of the revelation was how prisoners’ memories sometimes hovered on the brink of the hallucinogenic, or were obviously distorted. He played various sounds to one witness to try to help him recall the noise of the cell door shutting.

“He was saying it was louder, louder, louder, and we’re playing these enormous door sounds and I’ve got the reverb set to the doors of Notre Dame cathedral – that’s a 30-metre long nave. It couldn’t possibly have sounded like that.” Then the witness told Abu Hamdan he’d got it, that was it. But it wasn’t the sound of the door shutting, it turned out – it was the sound of the packs of bread being dropped outside the cell doors each morning.

What we were measuring … was about the condition of extreme hunger and what it does to the senses. The distortion spoke lucidly about the experience

“Of course it can’t have sounded like that – not even 50 packs of bread in a three-metre-high ceiling could sound like that. But what we were measuring was nothing to do with the door or the space – it was actually about the condition of extreme hunger and what it does to the senses. The distortion itself was speaking very lucidly about experience.”

This piece of evidence was unlikely to be useful in any forensic or judicial setting. But it did express a deep truth: metaphorical truth, psychological truth. It is this that Abu Hamdan has excavated, in the three works he’s presenting in Margate. The most substantial is a video called Walled Unwalled. Filmed in East Germany’s old radio studios in East Berlin, it consists of Abu Hamdan reading a script about the Saydnaya witnesses’ experiences, but also touches on other situations in which sounds heard through walls have been of profound importance. The Oscar Pistorius trial, for example, hinged partly on the defendant’s claim that he believed he had heard an intruder, rather than his partner Reeva Steenkamp, behind the bathroom wall before he shot her. But witnesses from neighbouring homes heard high-pitched screaming. Earwitness, rather than eyewitness, testimony was crucial.

The works on show in Margate are not “about” Saydnaya, or at least not only about it. They are also about the barriers nation states erect at their borders; the apparently boundary-free but highly surveilled world of the internet; how information leaks through the most impermeable-seeming walls; how what we hear is often deceptive and illusory. This is territory in which human experience can be best expressed not in forensic, journalistic or scientific language but in the language of art. “I’m quite romantic in thinking that art is a form of truth production, that a painting can manifest more of an essence of something than the thing itself,” he says.

Earwitness Inventory … Abu Hamdan’s assembled sound-effects kit on show in Beirut. Photograph: Agop Kanledjian/Courtesy the artist and Sfeir-Semler Gallery Beirut/Hamburg

In Beirut, I see some of his new work. It no longer turns so precisely on that fateful week in Istanbul. Abu Hamdan is now interested in reincarnation – a belief of the Druze, the religion of his father’s side of the family. One video work, Once Removed, which he completed this year, consists of an interview with a 31-year-old Druze man who understands himself to be a reincarnation of a boy who was killed in combat in 1984, aged 17. To make sense of the memories that he says resurfaced from his previous life, this young man, Bassel Abi Chahine, has constructed a large archive, including photographs, artefacts and interviews with survivors of conflict.

After the end of the Lebanese civil war, there was an amnesty, but there has been no truth and reconciliation. The war is not to be spoken of. It is not taught in school. Abi Chahine’s actions in gathering material – evidence – is controversial. His inherited memories “already implicate people”, says Abu Hamdan.

“A child soldier – that is already a crime right there. Coming back and saying you have memories of that does something very strange. He is talking about a war crime, but one that we do not have the legal capacity to deal with.” You might call it an embodied manifestation of inherited trauma – the next generation reliving the damage of the last. You might think of it as another type of leakage: not sound through walls, but memories through time.

Reincarnation … a scene from the video about Bassel Abi Chahine, who believes he was previously a Druze soldier. Photograph: Agop Kanledjian/Courtesy the artist and Sfeir-Semler Gallery Beirut/Hamburg

The work is not about identity as such, but it’s hard for him not to be thinking about his own at this moment. “I feel British,” he says, “and I also feel very Arab.” Abu Hamdan’s father is Lebanese, his mother a Yorkshirewoman. He was born in Amman in Jordan and largely brought up in York. His cultural awareness was forged in the Leeds DIY music scene, before he studied at Middlesex and Goldsmiths in London. Being nominated for the Turner prize, he says, “was a very moving moment for me, because it meant that culture, which was always the thing I had taken most from Britain, was still accepting of me”.

Unlike the Home Office. Recently, he went through the “humiliating” ordeal of securing a passport for his daughter. “I had to do a 13-month process of interviews and documentation, where I was showing them my wife’s ultrasound scans and so on, proving that I wasn’t fictionalising the child.”

It was nothing, he says, compared with what some have endured – those embroiled in the Windrush scandal, for example. But the experience of having his credentials as a Briton scrutinised so relentlessly alienated him from his own sense of Britishness, something he had never questioned before. After all that, he says, “I was just done.” It was part of the reason for moving to Beirut – the effort and expense required to secure his wife leave to remain (she is Lebanese) seemed an insuperably exhausting prospect.

‘I feel British, and also very Arab’ … Lawrence Abu Hamdan. Photograph: Miro Kuzmanović/Courtesy the artist and Maureen Paley, London

A week after we meet, I visit Turner Contemporary in Margate and see his work again. It strikes me that, in the end, what brings these works drawn from Saydnaya together is the way language and sound fail to meet each other. We have no precise language to describe sound. We always talk of something sounding “like” something else – we are already in the world of metaphor and poetry.

In Walled Unwalled, we learn that one Saydayna witness likened the sound of an inmate being beaten to the sound of a wall being demolished – for him, that was the only adequate description. But what does a wall being demolished sound like? And isn’t there something remarkable about a man who was literally walled up using the metaphor of a wall being demolished to describe the sound of torture?

This world of sound in Abu Hamdan’s art is a world of images that bleed into each other, unresolved – imprecise in a forensic sense, yet desperately telling. Some art makes you see the world differently. Abu Hamdan’s makes you hear it, feel it and understand it differently.

• The Turner prize exhibition is at Turner Contemporary, Margate, until 12 January. The winner is announced on 3 December.