  Preprint for a book chapter introducing Audio Content Analysis. With a focus
on Music Information Retrieval systems, this chapter defines musical audio
content, introduces the general process of audio content analysis, and surveys
basic approaches to audio content analysis. The various tasks in Audio Content
Analysis are categorized into three classes: music transcription, music
performance analysis, and music identification and categorization. The examples
for music transcription systems include music key detection, fundamental
frequency detection, and music structure detection. Music performance analysis
systems feature an overview of beat and tempo detection approaches as well as
music performance assessment. The covered music classification systems are
audio fingerprinting, music genre classification, and music emotion
recognition. The chapter concludes with a discussion and current challenges in
the field and a speculation on future perspectives.
