Electrophones: The Fifth Family, Added Later

Hornbostel and Sachs published their four families in 1914 — before anyone had built an instrument whose sound came from electricity itself rather than a physical vibrating body. The classification needed a fifth category once synthesizers, theremins and drum machines showed up, and it eventually got one.

Sound generated electronically

The theremin and the analog synthesizer generate their waveform electronically from the start — there's no string or reed to point to. The theremin's pitch and volume are controlled purely by the proximity of the player's hands to two antennas, with nothing touched at all.

Sound modified electronically

An electric guitar's string still vibrates like any chordophone, but once a fuzz pedal, a Leslie speaker, or a looper gets involved, the electronics are doing as much of the instrument's actual character as the string is. Where a strict classification draws that line is genuinely debated.

Case in point: a drum machine has no membrane, no skin, nothing struck at all — it's a membranophone's entire sonic signature synthesized from a circuit. The category it belongs to didn't exist yet when the family was named after it.

The fifth family is the reminder that any classification system is a snapshot of what existed when someone sat down to sort it.

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