Open Source Android Sound/Audio Apps

Kid3 audio tag editor can edit the tags of MP3, Ogg, FLAC, MPC & WMA files in an efficient way, convert between ID3v1 and ID3v2, set the tags of multiple files, generate tags from file names or vice versa and import from freedb, MusicBrainz and Disco

MuseScore is a free and open-source music notation software designed for composers, arrangers, educators, and musicians of all levels. It allows users to write, edit, and print professional-quality sheet music with no limitations or subscription fees. MuseScore Studio supports a wide range of instruments and ensembles, from solo piano and guitar to full orchestras and choirs. The software is easy to learn while still offering powerful tools for advanced notation and score layout. With support for MIDI input and formats like MusicXML and MIDI, MuseScore integrates smoothly with other music software and workflows. Built by a global open-source community, MuseScore continues to evolve through active development and community contributions. Support MuseScore at http://musescore.org/en/donate

CIOS Audio Core is the infrastructure and subsystem in Collective Intelligence Operation System. It is a cross platforms audio abstract interface, supports including Mac OS X, Linux, Android, iPhone OS and Windows 7.

XBMC Media Center is a free cross-platform media player software and entertainment system application framework for Linux, Mac, and Windows. XBMC is capable of playing back and streaming all popular video, audio, and picture formats out-of-the-box.