"opposing voices" is correct and usable in written English.
You can use it when you are referring to two different or conflicting opinions. For example: "The debate highlighted two opposing voices on the issue of healthcare reform."
For them, steamrolling opposing voices was just business as usual.
Only the leftists try to use extortion, pressure, threats to silence opposing voices.
However, the research's implied message reinforces antiwar activists' assertion that media outlets have marginalized opposing voices.
In the Soviet years, Moscow curbed opposing voices in the name of safeguarding Communism.
And China, not being a democracy, doesn't have to worry too much about opposing voices.
They proclaim to support free expression, yet have sought to restrict opposing voices.
In the Sonata Opus 109 every inner and opposing voice was granted its reflective sense of self.
In 1997, its president, Madanlal Damani, was the only opposing voice on a panel set up to consider the introduction of trading in derivatives in India.
While the top clubs have forged close links to UEFA thanks to a deepening friendship between Agnelli, the E.C.A. leader, and UEFA's president, Aleksander Ceferin, the leagues — faced with a critical leadership void at a vital moment — have struggled to present a cohesive opposing voice.
Princeton theology researcher Cole Bunzel, her opposing voice, disagrees.
In the two years since Sydney's controversial lockout laws were shoved down the throat of Australia's largest city, the Keep Sydney Open campaign has been an unabating opposing voice.
