When I arrived in Buenos Aires in 1991, much of the music being played on the radio was imported, middle-of-the-road rock. Radio stations were paid to play it, and it featured incessantly on many of the telenovelas, TV soap operas that appeared in the afternoon. Between the bland ballads and hard rock, the only other alternative was local cumbia dance music - essentially bastardised salsa.
It took me some time to find the counterpoint to this vapid scene - the Latin American protest song or Nueva Cancion (New Song), the gentle, folksy veneer of which concealed deep-rooted ideals inherited from the era of Fidel Castro and Che Guevara. It was informed by the work of writers such as Julio Cortazar and Gabriel GarcIa Marquez. The movement (whose Cuban incarnation was called "Nueva Trova", as in "trovador" or "troubadour") was pioneered across the subcontinent by dozens of artists committed to resisting the dictatorships that shadowed South American life from the late 1960s onwards. Remarkably, the music - and especially the lyrics - still mattered to many young Latin Americans when I arrived in the early 1990s.
The ethos of Nueva Cancion has often been likened to Catholic-Marxist liberation theology. Like the shanty-town priests who led that movement, its performers responded to the misery and desperation of the poor and exploited. Religious motifs were spun cleverly into lyrics that evoked the landscape, daily struggles and latent militancy of the poor mestizo (mixed-race) populations.
On 16 September 1973, just five days after the Chilean coup, the movement acquired a martyr when the folk singer VIctor Jara, one of the founders of Nueva Cancion, was murdered by the Pinochet regime. His body was found dumped in a morgue on the outskirts of Santiago. A brave morgue worker telephoned VIctor's British wife, the dancer Joan Jara, who went to collect her husband's corpse.
These were the days of Latin American idealism - and all the nations of South America had their own VIctor Jara. In Cuba, Silvio RodrIguez and Pablo Milanes melded folk and Latin rhythms with the ideals of the revolution. In Argentina, Atahualpa Yupanqui and Mercedes Sosa developed their own Nueva Cancion, its focus evolving from gentle portraits of rural life to the terror and tyranny of the aftermath of General Videla's 1976 coup. In Brazil, Caetano Veloso, Tom Ze and Gilberto Gil created tropicalismo, which mixed beat music, bossa nova and samba styles.
Many artists were forced into exile or prevented from recording; others spun songs from subtle metaphors, keeping their messages hidden from government-appointed censors but not from their fans. In a bid to lift the spirits of his fellow inmates, Jara even continued singing his simple, explicit narratives and stridently militant anthems in prison, prompting his gaolers to break the bones in his hands. Those bleeding hands, along with his face and clenched fist, have become iconic symbols of resistance in Chile.
But the enduring appeal of the New Song goes beyond T-shirt and bedroom-poster iconography. In the 1990s, democratic presidents across South America seduced voters with promises of a new era of belonging - to the free market, to the west, to the globalised world of imported foodstuffs, new cars, sushi restaurants and mortgages. In Argentina, where I lived for a decade, I saw Carlos Menem's fantasy of entering what he lovingly called "el primer mundo" (the first world) collapse when, in December 2001, the economy disintegrated. As the currency plummeted and anti-government marches became a feature of daily life, security forces showered protesters with rubber - and sometimes real - bullets, in the same way as they had during the dirty war years.
Jorge Luis Borges once observed that because history is younger in Latin America, it is also more immediate and compelling. Cultural fashions do not metamorphose every few minutes - which means that young Chileans, Cubans, Argentinians and Brazilians have a back catalogue of 30 years of political music that they still believe in. When Silvio RodrIguez gives a live show in Buenos Aires, Montevideo or Santiago de Chile, two or three generations of fans turn up.
In RodrIguez's case, part of his appeal is due to the symbolic importance of Cuba, the one country whose revolutionary movement got beyond manifestos and insurgency. But non-Cuban artists from the left continue to stir up similar emotions. Their songs matter because they question and interrogate. Yes, when they perform, the lighters are pulled out, just as tears fall round campfires when Latin American twentysomethings strum Silvio RodrIguez's "Ojala" or VIctor Jara's love song "Te recuerdo Amanda". But these songs have an urgency and underlying sense of rebellion that is far removed from the dreamy rural fantasia evoked by, say, a Fairport Convention ditty.
Silvio RodrIguez has said: "We never thought of ourselves as protest singers but as part of a tradition of troubadours." But in 1970s Latin America, almost all music could have the force of protest song. Charly GarcIa, an outspoken Argentinian rock singer who rose to prominence in the early 1970s, is as provocative when he sings longingly of a girlfriend "preparing the bed for two" as when he warns: "Your friends in the neighbourhood might disappear, the singers on the radio might disappear." Simple-sounding songs about being young, falling in love and hanging out all had political undertones. As a result, the concerts of many Nueva Cancion artists were either banned or cut short mid-performance by the police.
One of the strengths of Latin American song is that it stands as an alternative to, and an assault on, the weakness of so many other Latin American discourses, especially those of the church, the mass media and government. Even in today's democracies, the Nueva Cancion movement continues to draw attention to the corruption, impunity, the plight of the "desaparecidos" (the disappeared) and the continent's collective amnesia.
As a result of Nueva Cancion's continuing appeal, a protest ethos has spread beyond the confines of Latin American folk music. Cumbia was recently reborn as cumbia villera (slum cumbia), with stories of cocaine, crime and the culling of the middle classes replacing the usual sentimental lyrics about betrayal, beauty and seduction. An album by the Argentinian singer Sandra Luna, due out in October, contains a tango about the impoverished cartoneros (cardboard collectors) of crisis-crippled Buenos Aires. Usually regarded as melodramatic and essentially bourgeois, tango actually originated when migrant Italian workers and freed black slaves mixed and challenged each other in singing and dancing contests in the slums of Buenos Aires in the 1880s. Much Latin American folk music - both urban and rural - has similarly risen from the margins.
Meanwhile, in Britain, we don't seem to have moved on very far from the great debate of the late 1990s: "Who's best: Blur or Oasis?" But at least those bands, unlike today's offerings, were occasionally witty and anti-establishment. "Don't look anywhere in anger" seems to be the message of Travis, Coldplay and Radiohead. During the anti-war marches earlier this year, some musicians and journalists pointed out that protesters seemed to lack an anthem, even something as basic as "Maggie, Maggie, Maggie - out, out, out" or a stirring "Free-ee Nelson Mandela". Music academics claim that the voices of protest have fragmented into rap and hip-hop, as well as the leftist folk fringe led by artists such as the Waterson Family and Dick Gaughan (who names VIctor Jara as a formative influence). But maybe the problem is more that musical cultures directed by commercially driven hype inevitably fail to engage with politics.
After VIctor Jara's death, scraps of paper bearing the lyrics of his final songs were smuggled out of prison. One of them broke off with the words: "Silence and screams are the end of my song." In Latin America, that message has resonated through the work of the heirs of Nueva Cancion.
Many of the movement's leading figures have performed in Europe over the years, and Angel Parra, Quilapayun and VIctor Heredia are all appearing at the Barbican's forthcoming "Freedom Highway" festival, which is named after a documentary by Philip King (in turn inspired by lyrics from the Woody Guthrie song "This Land is Your Land"). From African, British and American fringe performers to more mainstream acts such as The Levellers and Chumbawamba, all the musicians taking part in the festival will be striving to prove that, without losing any of its coolness, pop music can still be political, critical and daring.
Quilapayun, Angel Parra and VIctor Heredia perform as part of the Barbican's "Freedom Highway: songs that shaped a century" from 19-22 September; call 0845 1207356 or visit www.barbican.org.uk/freedomhighway