Acoustics: Contributors' Notes

See <mitpressjournals.jorg/toc/lmj/-/22> for full access to LMJ21 and CD tracks, as well as supplemental materials. See <leonardo.info/lmj> for more information and resources.

Hauke Harder: Grigio Uno
For sine wave generators, amplifiers and open bass speaker chassis. Composed by Hauke Harder, 1996.

Contact: Hauke Harder. Web site: <www.haukeharder.net>.

In Grigio Uno, the unique sound of individual loudspeakers is made audible. Through the operation of bass speaker chassis (without box) at low frequencies, an acoustical short circuit takes place through which the tone cancels itself out. This phenomenon depends upon the size of the loudspeaker and the frequency of the signal. By this means, the overtones of the loudspeaker-the sounds of the partial tones-are made clearly audible but present themselves in composite as a "gray" sound. In order to make the analysis of the partial tones by ear more possible-as a prism allows perception of the colors contributing to white-an additional loudspeaker, playing a sine wave a fraction of a hertz different from the first loudspeaker, has been added. Now each partial tone has its own proportional beating frequency, so that, for example, the seventh partial beats seven times as fast as the fundamental tone. This produces a kind of repeating melody among the overtones as one unconsciously focuses on individual tones as each becomes louder. It takes some time to perceive this phenomenon, and with increased listening to the cycling, one slowly climbs up the ladder of overtones.

Fig. 1.

Hauke Harder, GRIGIO UNO for sine wave generators, amplifiers and open bass speaker chassis (sound installation), at the exhibition Punto e Basta (with Stephan Ullmann) at Stadtgalerie Kiel, Kiel, Germany, 1996.

(Photo © Helmut Kunde)

Grigio Uno was presented for the first time in 1996 at Stadtgalerie Kiel, Kiel, Germany (Fig. 1), and has been presented at several exhibitions and concerts since then.

Miguel Frasconi: Transverse Crescent (Revised)
Composed, performed and recorded by Miguel Frasconi, January 2012.

Contact: Miguel Frasconi, 72 Park Terrace West, #E45, New York, NY 10034, U.S.A. E-mail: <mfrasconi (at) earthlink (dot) net>. Web site: <frasconimusic.com>.

Two glass objects. One, a 7-inch-long shard from a broken bell-bowl, concave and crescent shaped. The other, a hand-blown, very thin disc with different textures on its face, created by Amanda Lind. These two objects interact in various ways, positioned to bring out certain resonant frequencies in each object.

When one plays the same set of bell-bowls over long periods of time, the constant vibration, through both striking and finger-bowing, gradually weakens certain areas of individual bowls (Fig. 2). If they reach the point of breakage they tend to do so along harmonically induced pathways. When a bowl breaks in this way, it is as if it has been released from the confines of its fundamental single pitch and is free to vibrate at different inharmonic frequencies in different areas of its broken form. This is most clearly heard in larger broken bell-bowls but can also be heard in the 7-inch, crescent-shaped shard used in this recording.

As is seen in images of Chladni plates [1] and studies of Cymatics [2], the vibrational energy dispersal of discs can be quite complex and harmonically rich. The location on the disc of the vibrational stimulus is of course very important to the resulting timbre. The particular disc heard here, with its multitextured face and its irregular shape, is thus perfect for acoustic explorations.

The act of rubbing any two objects together, or sliding one along the other, involves a transference of vibrational energy. Aside from the performative aspects involved, the resulting timbre depends on how easily either object is brought to vibration. With a substance whose molecular structure is as ambiguous as that of glass, and with objects as prone to vibration as the two on this recording, the timbre can become quite dense. This piece explores the mutually excited, absorbed and deflected vibrational energy at play when these two unique glass objects are brought together.

Fig. 2.

Miguel Frasconi...