In the anechoic chamber

One element of studying Music from the Present to the Past is to periodically reassess one’s own definition of what music is. Perhaps the biggest challenge to any definition comes with the task of putting on your own performance of John Cage’s indeterminacy piece 4’33”. This philosophical composition was created by Cage to demonstrate that any sounds can be seen as constituting music. Each performance is unique, and consists entirely of the incidental sounds heard during its four minutes and 33 seconds.

My own, done in the library of the teacher’s college I was working at in Tanzania, the librarian as my audience, consisted not of silence, but of the wind in the trees, a door slamming, voices ebbing and flowing in the college, birds chirping and one flying past the window, a text notification, a motorbike starting, chairs scraping on the floor, me scratching my own head, the librarian’s hanky flapping, her voice demanding “sing a song!”, then the noise of her leaving the room.

The perfect place to delve into the idea of silence is in an anechoic chamber. Cage got the inspiration for 4’33” from a visit he made in 1951 to the chamber at Harvard University. Such a chamber is designed to have surfaces absorbent of sound waves, meaning that each sound one makes is heard almost entirely from oneself, not from the reflections and echoes on surrounding objects that each sound usually carries with it to your ears. Reverberation is made up of early reflections (the first distinct echoes), and dense reverberation, consisting of many thousands of diffused echoes.¹

chamber-3

These reflections and echoes, as well as giving us aural information, enable our brains to locate ourselves in our environment (auralisation is the term for reproducing these acoustic sceneries using electroacoustics. For more information see the Icons of Sound website, here.

Wedge designs in the chamber walls trap sound waves, which become standing waves and do not escape as reflections. Sounds can therefore appear as if they are in a small area around you, and sounds made further from this area sound deadened and detached.

During my visit to the anechoic chamber at UCL, I felt as if I were in a space smaller than the chamber itself. Even when there are no other sounds, we can hear ourselves: Cage’s idea for 4’33” came from his realisation in the chamber that there is no such thing as silence. He could hear his body’s internal processes. Electronic producer A Sagittariun became acutely aware of his tinnitus during our chamber visit!

chamber-5

Anechoic chambers are not usually used for acoustic purposes, apart from experiments and testing speakers and other equipment. The chamber at UCL is used for the study of speech. For sound recording, musicians tend to use semi-anechoic chambers, aimed more at blocking out external noise than elimination of reflections.

I am going to write another blog about reverberant chambers and spaces, before looking at delay and reverb technology and sharing some sound clips.

View Charlotte’s blog here.

¹Richard Dobson & CDP


Originally published at WeAreOCA.