Musical Instruments
Classified by how the sound is actually made.
Instruments are grouped by the physical mechanism that produces the sound. The orchestra uses four familiar families; the Hornbostel-Sachs system used by musicologists is broader and more consistent.
Hornbostel-Sachs
| Class | Sound comes from | Examples |
|---|---|---|
| Chordophones | A vibrating string | Violin, guitar, piano, harp |
| Aerophones | A vibrating air column | Flute, trumpet, organ, clarinet |
| Membranophones | A stretched membrane | Drums, timpani |
| Idiophones | The body of the instrument itself | Cymbals, xylophone, bells |
| Electrophones | Electronic generation | Synthesizer, theremin |
This system puts the piano with the violin, because both sound a string, and separates cymbals from drums, which the orchestral scheme lumps together as percussion. It classifies by physics rather than by seating plan.
What sets the pitch
For a string: length, tension and mass per unit length. Shorter, tighter and thinner all raise pitch, which is why a violin is small and a double bass is not. For an air column: length, and whether the tube is open or closed at one end. A closed tube sounds an octave lower than an open tube of the same length, which is why a clarinet reaches lower than a flute of similar size.