Prisons are noisy places constantly filled with loud voices and the clanging of metal doors.
But some cell blocks across the UK now echo with new, unfamiliar sounds of Indonesian gamelan.
The Good Vibrations Project has worked with more than 1000 individuals in 17 different UK prisons, young offender institutions and secure hospitals over the past four years.
The Indonesian drums, xylophones, gongs and bamboo flutes they use are so alien to most inmates that they create a level playing field.
Nobody is expected to be an expert and very quickly people with no musical skills or background can learn traditional pieces and produce melodious sounds.
"I'd never heard anything like it before", says Martin Gwynn, a gamelan workshop participant who has just completed a sentence at Dovegate prison in Staffordshire.
"My favourite was the big gong - I couldn't leave that one alone, I loved playing it. The instruments were so beautiful and expensive looking and I couldn't believe they trusted us enough to let us loose on them. "
Martin, a man in his late 30s, is just out of jail for the fifth time after a sentence for drug dealing. He says he was "a bit of a loner" in prison but the gamelan project forced him to communicate more with staff and other inmates.
"You have to learn to listen and work with people around you and I hadn't done anything like that for a while.
"Now I find it easier to talk to strangers, to look them in the eye and I hope that will help me this time when I'm looking for a job."
John's teenage daughter, Danielle, listened to a CD her father made with the other inmates. "He was very proud of it and I think it has made him feel a bit more hopeful about life."
John Pawson, who has led gamelan workshops in several prisons, says the music also promotes calm especially among the mentally ill - a significant proportion of the prison population.
At Peterborough prison in the east of England, he worked with disturbed women who had repeatedly cut themselves with razors, knives, even ballpoint pens.
A month later he returned to see if anything had changed.
"All of them had reduced their self harming and there was one lady who was a prolific self-harmer before we got there and she had actually stopped completely.
"I can't say that we can take full credit for that but something had changed and we asked her what do you do and she said whenever I feel bad I just tap out the rhythm with my fingers and sing the tune in my head.
"Just remembering it helped her to feel good when she was feeling bad, as simple as that really".
To assess the longer-term effects of taking part in Good Vibrations projects, prisoners were interviewed six to nine months later by researchers from Birmingham City University. Their report found the music project had a consistently positive impact on offenders.
It encouraged team-building, and improved participants' relationships with other inmates and guards.
Professor David Wilson who co-authored the report, believes that too much time and money has been wasted on rehabilitation schemes for prisoners designed by psychologists, such as cognitive behaviour therapy, or CBT.
"These cognitive behavioural therapy courses are popular with politicians because they seem to promise that in a magic silver bullet they can, in just a few weeks or months, overcome a whole life time of engrained deprivation such as homelessness, alcoholism or addiction to drugs.
"But that simply doesn't stand up to any kind of objective academic scrutiny."
However, there is some evidence to suggest that over time, such therapy can help with the rehabilitation of prisoners.
He believes creative activities provide a vital bridge to learning more conventional skills like numeracy and literacy that help inmates cope when they get out of prison and also persuaded many prisoners to engage with further learning and education.
"It is still a staggering statistic that 50 per cent of the sentenced male prison population in this country has a reading age of less than eleven.
"You don't have to be a rocket scientist to know that you have to be able to do something about that to help that person to gain independent employment when they leave jail.
"Now we also have to be far cleverer than we have been in the past because these are clearly failed learners and we have got to approach them in new and imaginative ways rather than simply replicate the educational environment that existed in the community in which they failed".
Arts projects in prisons have come under fire for being too soft, but Professor Wilson says they they definitely play a role in rehabilitation.
"You try and get somebody who has been school excluded or has failed every exam they have gone into and engage that person in a chalk and talk environment - in a prison environment that is simply not on".
"One of the ways to engage with them is to get them in on an arts based project so that they become comfortable with the environment and more accepting of the fact that they are able to learn".
Mural artist Angela Findlay, who goes into prisons to paint with inmates, agrees that many prisoners are seemingly allergic to traditional teaching.
Many talented, intelligent people she meets have been written off at school because they suffer from problems like dyslexia or because they are simply too disruptive.
She also deliberately pushes the prisoners in her art class to examine their past behaviour, confront their crimes and empathise with victims.
Maxine, a former drug mule, took part in a creative project run by Music in Prisons. The group is part of the Irene Taylor Trust which was set up in 1995 in memory of the wife of the late Lord Chief Justice Peter Taylor who was passionate about both penal reform and music.
Composing and performing songs helped Maxine overcome her sorrow at being separated from her small daughter.
"I wrote a lullaby called Sleepy Eyes", she says. "When you are in your prison cell it is like being in the grave. But through the music your voice can be heard.
"Your children can know that you still love them and you can keep that family connection alive."
Maxine says that helps people to adjust more quickly to life once they are released.
For ex-offender Andrew Brown, theatre is the best kind of therapy.
"People like me have just got this kinetic energy building up inside us" he says.
"I think acting it allows you to let off this energy in a controlled manner. All that boredom, anger, frustration - drama just helps me to release it all."
Andrew who describes himself as a "natural born show off" recently performed in a play about knife crime staged by the London based theatre company, Only Connect.
The company believes that the performing arts - and theatre in particular - have the potential to transform lives and help heal families and communities.
Andrew would ideally like to work one day as a professional actor, but he knows it is a notoriously tough profession and he is keeping his options open.
Now he often goes into schools to warn teenagers about the dangers and consequences of carrying knives.
He tells me that acting in the play has inspired him to give something back to society and become a community volunteer.
"Okay, I'm not Al Pacino but a lot of criminals or ex-criminals or whatever you want to call us, we only get recognised for doing something bad", he says.
"So the minute you get applause for doing something good it touches your heart and makes you believe in yourself. It made me want to cry."
Lucy Ash's presents Fresh Start on the BBC World Service for which she visits prisons around the world to explore the imaginative methods they are using to stop re-offending.