“I had to like, open the bruise up, and let some of the bruise blood come out to show them” says Daniel Hamm. In 1964, he is nineteen-years old, one of six black youths arrested for the murder of a white woman in Harlem. He did not commit the crime and he is beaten while in jail. He has to puncture one of his own bruises to prove this to the police.

Working with tape footage for a collage in benefit of the ‘Harlem Six’ two years later, composer Steve Reich writes the piece ‘Come Out’. He plays this fragment of speech, then loops it in unison with itself; the two samples gradually fall out and then back into phase with each other across thirteen minutes.

“‘Come Out’ functions instead as a living, pulsing document of police brutality and racial oppression”

Reich’s earlier work ‘It’s Gonna Rain’, with its street-preacher loop, spoke to Cold War paranoia and religious doomsaying, but ‘Come Out’ functions instead as a living, pulsing document of police brutality and racial oppression from the mouth of one of its many victims.

“They shaved us, they tattooed a number on our arm” says a woman identified as Rachella. She is a survivor of the Holocaust. On ‘Different Trains’ from 1988, Reich repeats the use of “speech-melody” in a three-movement piece for string quartet and tape, which interposed his own rail journeys across the United States as a child in the 1940s with those of European Jews on Holocaust trains. He interviewed three survivors: Paul, Rachel and Rachella and all three give their spoken testimony to events.

Every fragment of speech is imitated by viola and cello, playing the melody back as the entire piece turns and shifts with each new piece of testimony. The strings, tense and dissonant, form a claustrophobic, driving mass in the vein of Penderecki that envelops the listener but nonetheless allows the historical account to take centre stage. What makes ‘Different Trains’ all the more powerful is that Reich himself is Jewish and may well have faced the same fate as those he sampled had he been on a different continent.

A chorus of voices. The sound of men working the soil with hoes. Benny Will Richardson leads prisoners in a work song named ‘Stewball’ in Lambert Camp at the maximum security Mississippi State Penitentiary. It is 1947 and they are being recorded by folklorist and archivist Alan Lomax.

Some sixty years later this same clip is used by Beyoncé Knowles on the song ‘Freedom’ alongside a 1959 field recording, also by Lomax, of Reverend R.C. Crenshaw and the congregation at the Great Harvest Missionary Baptist Church in Memphis. These samples not only provide context for a song about black womanhood and the hope for freedom from oppression, but more broadly testify to the historic experiences of black people in America; to their rich religious and cultural traditions and to their imprisonment and repression.

Besides: a brief exploration of Malian music

Beyoncé cannot attest to being a prisoner in Lambert Camp or a congregation member in a Memphis baptist church any more than Steve Reich can attest to being a survivor of the Holocaust, but through being black and Jewish respectively, they share cultural and ethnic heritage with the people whose voices they have chosen to amplify. The encodation of the voices of the past into musical works allows artists to reflect on and attest to realities they did not witness first-hand.

These are voices which, in their contemporary societies, were neglected and silenced. Today, when political actors and fringe extremists seek to erase histories of discrimination and oppression, they are more vital than ever. When someone denies the reality of the Holocaust, ’Different Trains’ is not just a work of art or a piece of music but a living rebuttal. When someone denies the reality of the institutional oppression of black people in the United States, ‘Freedom’ is a refutation and fundamental proof. It is often said that music gives people a voice, but perhaps we should also think about what voices can give to music