We present an overview of the most recent developments in
polyphonic music retrieval and an experiment in which we compare two
harmonic similarity measures. In contrast to earlier work, in this paper
we specifically focus on the symbolic chord description as the primary
musical representation and the similarity between sequences of these descriptions.
In the experiment we compare a geometrical and an alignment
approach to harmonic similarity, and measure the effects of chord description
detail and a priori key information on retrieval performance. For this
experiment a large new chord sequence corpus is assembled. The results
show that a computational costly alignment approach significantly outperforms
a much faster geometrical approach in most cases, that a priori
key information boosts retrieval performance, and that using a triadic
chord representation yields significantly better results than using more
simple or more complex chord representations.