A nineteenth-century tone generator used 10 tuned forks to synthesize timbre

Evidence

Toward the end of the nineteenth century, Rudolph Koenig used a bank of Helmholtz resonator-enhanced tuning forks to build a tone generator. The forks were set in frequency, one to each equally spaced partial of a fundamental, perfectly tuned to vibrate at integer multiples of the lowest frequency member of the collection. Figure 20.11 shows one such instrument, an assembly of 10 electromagnetically driven tuning forks, each coupled with its own Helmholtz air resonator, exploiting the NFC amplification mechanism. Apart from the issue of phase control, this apparatus made possible a 10-partial version of Falstad’s Fourier applet. This instrument was built to investigate the connection between the amplitudes of many partials and timbre. It was thought for a time that 10 partials would be sufficient to imitate vowel sounds, but normally more are needed, as we saw in chapter 17. — Eric J. Heller, Why You Hear What You Hear- An…, 1902

Categorization

• XREF: Connects to physiology of timbre and vowel perception established in chapter 17 and to Fourier synthesis.
• SHARE: A mechanically realized Fourier synthesizer from 1890s — ideal for someone into acoustics or instrument history.