  The average individual is typically a mediocre singer, with a rather
restricted capacity to sing a melody in tune. Yet when many singers are
assembled to perform collectively, the resulting melody of the crowd is
suddenly perceived by an external listener as perfectly tuned -as if it was
actually a choral performance- even if each individual singer is out of tune.
This collective phenomenon is an example of a wisdom of crowds effect that can
be routinely observed in music concerts or other social events, when a group of
people spontaneously sings at unison. In this paper we rely on the
psychoacoustic properties of pitch and provide a simple mechanistic explanation
for the onset of this emergent behavior.
