Double siren
From Ccpi
The double siren is an instrument used in experiments in the theory of music. It is capable of producing octaves, fifths, fourths, major and minor thirds, whole and semi-tones, beats, cancellations, etc. Notable experiments include the vibration of overtones, interference, tonal depth, and combined tones.
A double siren consists of two coaxial Dove sirens—rotating disks containing series of holes. As air is periodically allowed to move through the holes, a distinct tone is created. On top of the instrument is a crank for adjusting the frequencing of sound by rotating the holes of the upper disk. In addition, each series of holes can be opened or closed.
In 1885, Helmholtz published the first description of this instrument, in his Die Lehr von den Tonempfindungen als physiologische Grundlage für die Theorie der Musik (On the Sensations of Tone as a Physiological Basis for a Theory of Music). Each disk on his siren contained eight series of holes for producing multiple musical notes. To clarify the notes, brass chambers were placed over each siren to dampen any extra frequencies.
[edit] References
- Hafter, Ervin. Helmholtz's Double Siren. Berkeley Audiotory Perception Lab. URL accessed 2006-02-20.
- Kohl, Max. Physical Apparatus. Price List No. 50. Vols II and III. p 422.
- Pantalony, David. "Rudolph Koenig’s Workshop of Sound: Instruments, Theories, and the Debate over Combination Tones". Annals of Science. Vol. 62, No. 1, January 2005, 57–82.
- Greenslade, Thomas. "The Siren". Historical Physics Teaching Apparatus. URL accessed 2006-02-26.
