MEMBRANOPHONES
Membranophones produce sound by stretching a membrane over an opening. Most, but not all, membranophones are called drums. They are classified according to the following features:
material
shape
skins (head)
fastening of the skins
playing positions
manner of performance
CHORDOPHONES
Chordophones are instruments with strings. The number of stringed instruments can be reduced to four functional types:
zither
lute
lyre
harp
ELECTROPHONES
Instruments where vibrations are produced mechanically or reproduced mechanically.
DURATION is the length of time a pitch or tone is sounded. Musical time is usually organized in terms of a basic unit of length, known as a BEAT or regular pulsation. Three terms related to duration are meter, rhythm, and tempo.
Meter refers to regularly recurring pulses of equal duration, generally grouped into patterns of two, three, four, or more, with the first pulse in each group accented. These patterns of strong and weak pulses are called beats.
Rhythm is sometimes used, like duration, to refer to all phenomena related to the sounding of a tone through time. Specifically, it can refer to the uneven durations of particular notes, overlaying or operating within the meter.
Tempo: speed of the pulse or meter.
TEXTURE
MONOPHONIC, or single-voiced. (Voice refers to an individual part or line, even when we are talking about instrumental music).
HETEROPHONY usually results in a melody combined with an ornamented version of itself.
POLYPHONY occurs when two or more lines are combined, distributing the melody among the voices.
HOMOPHONY, where a single voice takes over the melodic interest, while the accompanying voices take a subordinate role.