It’s controversial. So much so, there’s a conspiracy theory about it. Pythagoras was a fan, and contemporary tuning practices are not. What we’re talking about is Verdi’s A – an A that vibrates at 432 Hz, slightly slower and therefore lower than standard A which vibrates at 440 Hz. In the debate as to what the correct pitch for concert A should be, the argument rages with pundits in both camps sticking to their guns. Musicians Colin Reid and Alan Shields explore the 432 terrain to discover whether or not there is a de nite answer.