  Digital audio processing tools offer music researchers the opportunity to
examine both non-notated music and music as performance. This chapter
summarises the types of information that can be extracted from audio as well as
currently available audio tools for music corpus studies. The survey of
extraction methods includes both a primer on signal processing and background
theory on audio feature extraction. The survey of audio tools focuses on widely
used tools, including both those with a graphical user interface, namely
Audacity and Sonic Visualiser, and code-based tools written in the C/C++, Java,
MATLAB, and Python computer programming languages.
