  We present a statistical analysis of music scores from different composers
using detrended fluctuation analysis. We find different fluctuation profiles
that correspond to distinct auto-correlation structures of the musical pieces.
Further, we reveal evidence for the presence of nonlinear auto-correlations by
estimating the detrended fluctuation analysis of the magnitude series, a result
validated by a corresponding study of appropriate surrogate data. The amount
and the character of nonlinear correlations vary from one composer to another.
Finally, we performed a simple experiment in order to evaluate the pleasantness
of the musical surrogate pieces in comparison with the original music and find
that nonlinear correlations could play an important role in the aesthetic
perception of a musical piece.
