HUMAN PERCEPTION AND COMPUTER EXTRACTION OF MUSICAL BEAT STRENGTH

George Tzanetakis, Georg Essl
Computer Science, CISE Department
Carnegie Mellon University, University of Florida
gtzan@cs.cmu.edu, gessl@cise.ufl.edu
Perry Cook
Computer Science and Music Department
Princeton University
prc@cs.princeton.edu

ABSTRACT
Musical signals exhibit periodic temporal structure that create
the sensation of rhythm. In order to model, analyze, and retrieve
musical signals it is important to automatically extract rhythmic
information. To somewhat simplify the problem, automatic algorithms 
typically only extract information about the main beat of
the signal which can be loosely defined as the regular periodic sequence 
of pulses corresponding to where a human would tap his
foot while listening to the music. In these algorithms, the beat is
characterized by its frequency (tempo), phase (accent locations)
and a confidence measure about its detection.
The main focus of this paper is the concept of Beat Strength,
which will be loosely defined as one rhythmic characteristic that
could allow to discriminate between two pieces of music having
the same tempo. Using this definition, we might say that a piece
of Hard Rock has a higher beat strength than a piece of Classical
Music at the same tempo. Characteristics related to Beat Strength
have been implicitely used in automatic beat detection algorithms
and shown to be as important as tempo information for music classification 
and retrieval. In the work presented in this paper, a user
study exploring the perception of Beat Strength was conducted
and the results were used to calibrate and explore automatic Beat
Strength measures based on the calculation of Beat Histograms.


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DAFX4
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