Arturo Toscanini firmly believed that "the vibrations of high notes beating frequently on a singer's brain make him stupid."
It is a notion held secretly or sheepishly by a number of music's leaders, supported by a body of folklore and some medical opinion. According to the theory, the higher the voice, the more stupid the singer particularly tenors, whose resonant upper register causes more acute brain-beating frequencies.
Basses, baritones and contraltos have more sense because they have fewer vibrations.
In Italy, a man would much rather be called a cuckold than be...