The topic for today’s class was matter. We started off with a lecture by Dr. Vuk Uskokovic about matter on a small scale. After a short break, we transitioned into Ivana’s lecture, where she discussed her personal artworks. In particular, she showed us how sound and matter not only coexist, but are connected with one another. Matter can affect sound. An example of this concept is the anechoic chamber, or no-echo chamber. It intrigued me as I was interested in how one could make a room completely silent, devoid of sound and electromagnetic waves reflecting off surfaces. Living in a big city, silence is scarce, almost strange if possible. Therefore, I was excited to learn how sound could be absorbed completely.

Ivana explained that an anechoic chamber was a room that was designed to absorb all reflections of sound or electromagnetic waves. Interestingly, these chambers are often built with its future use in mind. Depending on the type of device being tested, the chamber may need to have specific dimensions. Despite variations in chambers, all designers maximize absorption of sound or electromagnetic waves using numerous approaches. The size of the room can impact the amount of absorption and generally has minimum dimensions. Foam wedges, often three feet deep, are used to help eliminate the reflections of these waves. The triangular shape of the foam aids in dissipating sound. These are placed on the walls, the ceiling, and the floor of the room of a full anechoic chamber. A mesh grate is installed above the floor’s wedges to allow for the device’s equipment to be set up. However, when testing heavier equipment, such as a car or industrial instruments, the mesh grate is an inadequate support. Thus, chambers can have solid floors (no wedges on the floor), making these rooms semi- or hemi-anechoic chambers. Materials that make up the walls of the anechoic chamber can also vary; some chambers contain a layer of fibreglass which is effective in absorbing the high and low frequencies of sound, while others contain layers of thick dissipative foam.

Anechoic chambers absorb the sound or electromagnetic waves. Devices that are tested are generally loud machines that need to have precise sound tests done. The room allows for this precision as most if not all waves are absorbed. However, anechoic chambers can have great effects on humans. These rooms are so quiet that it can cause people to become disoriented and paranoid. The smallest sounds, such as the blood flowing in your body, or the slight rustling of your clothes, can be exaggerated because the rooms are so quiet. This is because some sounds nearly don't exist while others are amplified. Footsteps are silenced by the room’s absorption abilities. Since these noises are silenced, people tend to hear their bodily noises much clearer. Breathing, stomach digestion, and heartbeat are all made aware of the person, and can cause them to become uncomfortable. In general, it is advised to be in an anechoic chamber no longer than 45 minutes as it may cause negative side effects to one’s psyche. People are so used to a world where there is space, sound reverberation, and constant sensory stimuli, that one’s sense of normalcy is challenged in an anechoic chamber.

The triangular shape of the foam wedges helps in dissipating sound. Sound waves interacting with the wedges at 100Hz and 300Hz.

Wedges of an anechoic chamber which help to absorb the sound waves and prevent reflection.

Resources:

“Anechoic Chamber.” Bliss Lab, blisslab.pratt.duke.edu/research/acoustics/anechoic-chamber#:~:text=Sound%20absorption%20is%20achieved%20through. Accessed 26 June 2024.

Denys, Sam, et al. Fear Influences Phantom Sound Percepts in an Anechoic Room. Vol. 13, 26 Sept. 2022, www.ncbi.nlm.nih.gov/pmc/articles/PMC9549870/, https://doi.org/10.3389/fpsyg.2022.974718.

“The Basic Rules for Anechoic Chamber Design.” Resources.pcb.cadence.com, 21 Mar. 2022, resources.pcb.cadence.com/blog/2022-the-basic-rules-for-anechoic-chamber-design.

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