Koenig’s wave siren synthesized tones by varying air slit obstruction height.

Evidence

Realizing this, Koenig invented his wavetable synthesis method, or wave siren. A slit of air emerging from a pressure source strikes a proximate rotating metal band of variable height. The air escapes in proportion to the height of the unobstructed portion of the slit (figure 24.10). The shape of the bands were painstakingly computed and cut, using a photographic process to reduce a large mockup of the curve to the right size for the template. However, the vagaries of real airflow around such obstacles may have caused far more deviation from a pure phase effect than any error in the curves. — Eric J. Heller, Why You Hear What You Hear- An…, 2249

Categorization

• DEFINE: Describes what a wave siren is and how airflow proportional to slit obstruction produces synthesized tones.
• SEED: A historical angle on how 19th-century acousticians grappled with the phase problem using physical analogs of what modern wavetable synthesis does digitally.