EURASIP Journal on Advances in Signal Processing
Volume 2007 (2007), Article ID 56561, 15 pages
doi:10.1155/2007/56561
Research Article

Audio Key Finding: Considerations in System Design and Case Studies on Chopin's 24 Preludes

Ching-Hua Chuan1 and Elaine Chew2

1Integrated Media Systems Center, Department of Computer Science, USC Viterbi School of Engineering, University of Southern California, Los Angeles 90089-0781, CA, USA
2Integrated Media Systems Center, Epstein Department of Industrial and Systems Engineering, USC Viterbi School of Engineering, University of Southern California, Los Angeles 90089-0193, CA, USA

Received 8 December 2005; Revised 31 May 2006; Accepted 22 June 2006

Academic Editor: George Tzanetakis

Copyright © 2007 Ching-Hua Chuan and Elaine Chew. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We systematically analyze audio key finding to determine factors important to system design, and the selection and evaluation of solutions. First, we present a basic system, fuzzy analysis spiral array center of effect generator algorithm, with three key determination policies: nearest-neighbor (NN), relative distance (RD), and average distance (AD). AD achieved a 79% accuracy rate in an evaluation on 410 classical pieces, more than 8% higher RD and NN. We show why audio key finding sometimes outperforms symbolic key finding. We next propose three extensions to the basic key finding system—the modified spiral array (mSA), fundamental frequency identification (F0), and post-weight balancing (PWB)—to improve performance, with evaluations using Chopin's Preludes (Romantic repertoire was the most challenging). F0 provided the greatest improvement in the first 8 seconds, while mSA gave the best performance after 8 seconds. Case studies examine when all systems were correct, or all incorrect.