Girl With A Musical Instrument

- Membranophones, which produce sound by a vibrating a stretched membrane; they may be drums (further sorted by the shape of the shell, which are struck by hand, with a stick, or rubbed, but kazoos and other instruments which use a stretched membrane for the primary sound (not simply to modify sound produced in another way) are also considered membranophones.
- Chordophones, produce sound by vibrating one or more strings; they are sorted into according to the relationship between the string(s) and the sounding board or chamber. For example, if the strings are laid out parallel to the sounding board and there is no neck, the instrument is a zither whether it is plucked like an autoharp or struck with hammers like a piano. If the instrument has strings parallel to the sounding board or chamber and the strings extend past the board with a neck, then the instrument is a lute, whether the sound chamber is constructed of wood like a guitar or uses a membrane like a banjo.
- Aerophones, produce a sound by with a vibrating column of air; they are sorted into free aerophones such as a bullroarer or whip, which moves freely through the air, flutes, which cause the air to pass over a sharp edge, reed instruments, which use a vibrating reed, and lip-vibrated aerophones such as trumpets, for which the lips themselves function as vibrating reeds.
Sachs later added a fifth category, electrophones, such as theremins, which produce sound by electronic means. Within each category are many subgroups. The system has been criticised and revised over the years, but remains widely used by ethnomusicologists and organologists.