Voice Chamber ProjectPosted: July 11, 2014
Sound does not exist in a vacuum, particularly not the sound of the human voice. When a voice is heard in a space, the quality of the sound is defined by the quality of the collisions between the sound and the physical infrastructure of the space. Frank Sinatra crooned into mics in lounges with absorbent velvet curtains, cushy couches, and plush carpeting. Children’s choirs are often presented in large churches and cathedrals, where the overtones are free to reverberate back and forth on themselves for many seconds before fading out. Each space greatly highlights the particular beauty of each sound. As veteran pop star and aesthetician David Byrne points out in the 1st chapter of his book How Music Works, music is made to suit the space it will inhabit, and its success depends on what kinds of sound that space affords.
The Piezoelectric Voice Chamber project was an exploration into the creation of a microphone with a very specific acoustic ‘personality.’ I wondered: how can the specific materiality of a space affect the particular aesthetic qualities of the sound of the human voice?
The piezo voice chamber is a hollow volume that is airtight except for an aperture large enough to speak into. A piezoelectric transducer is attached to the surface of the chamber and connected to a 1/4” instrument jack; it acts like a traditional contact microphone in that it senses only structure-borne sound and not sound waves in the air. The captured sound can then be amplified live or recorded.
The working hypothesis for the experimental design process was: Given volumes of identical shape and form, different materials will react differently to a sound. The results had to be measurable in some way. I chose to measure the acoustic absorption of two materials: one was a “papercrete” material made from newspaper pulp, flour, iodized salt, and water. The other was artist’s plaster.
I analyzed the shape of the waveforms generated via the piezoelectric transducer when vibrating in reaction to 14 different vocal sounds in voice chambers of each material composition. In order to do this, I built a simple oscilloscope in Processing and ran the audio through my Macbook’s audio board via a MOTU 8pre audio interface. Finally, I was able to compare the shapes of the waveforms generated by the two different materials in reaction to identical sounds.
Form and material process