Music by Beatle George Harrison and pieces by classical composers were used to torture political opponents of the regime of Chilean dictator Gen Augusto Pinochet.
On the 40th anniversary of Pincohet's seizure of power, Manchester University researchers claimed that agents of his regime used My Sweet Lord by Harrison to "break" socialist revolutionaries.
The tune was written by Harrison as a celebration of his Buddhist faith and featured on his 1970 album, All Things Must Pass. But Chilean secret police used it as part of a "torture soundtrack", said the university.
Dr Katia Chornik said: "Pinochet's system used music to indoctrinate detainees, as a form of punishment, and as a soundtrack to torture.
"Played at intensely high volumes for days on end, otherwise popular songs were used to inflict psychological and physical damage."
Also on the torture soundtrack were tunes by Spanish crooner Julio Iglesias and classical pieces by Beethoven - echoing scenes in Stanley Kubrick's film, A Clockwork Orange, in which the protagonist is locked in a room by an old adversary and subjected to the same piece of symphonic music played over and over again until he is driven to attempting suicide.
But music also played a therapeutic role for people confined in jails in Chile, claimed The Sounds of Memory: Music and Political Captivity in Pinochet's Chile report.
"Music brought prisoners together because it was a way to deal with their terrible suffering," said Chornik.
"But music was also a form of testimony. Many prisoners did not officially exist, so many were to disappear without trace and songs were a way of remembering who they were and what they believed in."
Many of those in jail were political prisoners who wanted to return to a socialist state after the democratically elected leftist government of Salvador Allende was toppled by an army coup in 1973.