This is generally true of tuning an instrument. It's how I've always tuned guitar. In the case of guitar you only need a starting E tone and can figure out the

This is generally true of tuning an instrument. It's how I've always tuned guitar. In the case of guitar you only need a starting E tone and can figure out the rest by yourself. In the case of an orchestra or concert band, everyone plays at once during tuning and you use the dissonance as a guide. Once there is no dissonance, everyone is in tune.