Object, Instrument, Technology

This rack has 3 square and 3 circular brass plates of varying dimensions. It was used to demonstrate the effect of changes in the size and thickness of plates on both their tone and the Chladni figures that they produce. A plate that is the same size as the one next to it, but double the thickness, will produce a note twice as high, while a plate that is half the area of the one next to it, but double the thickness, will sound a note that is four times higher.

 

 

Text
Robartes, Francis. 1692. “A Discourse Concerning The Musical Notes Of The Trumpet, And Trumpet-Marine, And Of The Defects Of The Same”. Philosophical Transactions 16 (95): 559-563.
Video
Chladni, Ernst Florens Friedrich. 2012. “Chladni Plate Demonstration From The National Museum Of American History”. Smithsonian National Museum of American History. https://youtu.be/KEttRmu2kGk.
Object, Instrument, Technology

The German scientist Ernst Chladni was one of the pioneers of experimental acoustics. His research on different kinds of vibrations served as the basis for the scientific understanding of sound that later emerged in the 19th century. 

Object, Instrument, Technology

In its simplest form the siren consists of two metal disks, each having the same number of regularly spaced concentric holes. The lower disk is mounted on the base of the siren, while the upper disk is mounted on a steel shaft just above it. As air is forced through the system, the upper disk begins to rotate. As it spins, the holes in the two disks briefly line up and then quickly close. Each time they do this, a brief puff of air is released. Each of these puffs acts like a single sound wave, and if enough of them are produced we perceive them as a continuous musical sound.

Text
Chladni, Ernst Florens Friedrich. 1830. Die Akustik. Leipzig: Breitkopf und Härtel.
Object, Instrument, Technology

Having developed several glass harmonicas, in March 1790 Chladni announced the invention of a new instrument that he called the euphone. Resembling an organ and piano, and unlike the harmonica from which it was derived, the euphone was composed of glass strips (as opposed to bowls or vessels). Each strip was a different length and generated a different tone. Chladni discussed the relationship between the lengths and the tones in his Entdeckungen über die Theorie des Klanges.

Object, Instrument, Technology

This photograph shows a three-dimensional representation of sound using paper. The spectrum (frequencies from low to high) is represented by an arrangement of single strips of paper, with lower frequencies in the foreground. The changes in the spectrum over time are visible as variations in the profile of the paper strips, if read from left to right. Such paper models were used at the Technische Universität Berlin in the 1960s to represent the sounds of speech (phonetics) and music (acoustics).

Image
“Handmade Paper Waterfall Plot: Beethoven’s 8Th Symphony (1)”. n.d.
Object, Instrument, Technology

In 1894, Olaus Henrici (1840-1918) of London devised a harmonic analyzer for determining the fundamental and harmonic components of complex sound waves. It consists of multiple pulleys and glass spheres, called rolling-sphere integrators, connected to measuring dials. The image of a curve (for example, a phonodeik tracing of a sound wave) is placed under the device. The user moves a mechanical stylus along the curve’s path, tracing out the wave form.