of my installation at Ars Electronica is undertaken in collaboration
with Katie Egan and pertains to a question about two "singing plants".
At a point in time now almost exactly two years ago, a young pre-med
student approached me with an interesting question. She had recently
returned from South America where she had carried on field work in the
Ecuadorian rain forest. There she had encountered a Native American
brujo or "medicine man". The brujo had told her that a given
species of plant in the mountains sings a different song than the same
species of plant in the valley. The student wanted to know if it was
possible to "listen" to plant cells.
phenomena, including "sound", are the result of mechanical
movements of physical objects within or upon the surface of a solid,
gaseous, or liquid acoustic medium such as steel, air, water, etc..
In the case of the acoustic phenomena we call "sound", the
movement of physical objects occurs at or close to audio frequency so
that the resulting waves or pattern of waves passing through an acoustic
medium do so at audio frequency. When these audio frequency waves impinge
on the human listening apparatus (the inner ear) the result is that
"sound" is perceived in the human brain.
with, it seemed to me that the problem wasn't that cells are naturally
"mute". Many of them - and their flagella, cilia, pili, etc.,
- are normally at least partly engaged in activities that appear to
occur at audio frequency. Further, no non-dormant living organisms are
known to exist in vacuum or otherwise outside of an acoustic medium.
time, there were to my knowledge no existing microphones of sufficient
sensitivity to register microacoustic signatures of individual (microscopic)
cells. The function of conventional microphones generally depends on
the mechanical motion of crystals or diaphragms that react to impinging
sound waves. Sound waves generated by individual cells or microorganisms
are simply too weak to effect such movements in mechanical listening
microphones translate audio frequency sound waves into audio frequency
electrical (electromagnetic) signals. These electrical signals may then
be routed through amplifiers, equalizers, and other electronic audio
equipment and eventually into speakers or earphones where electric signals
are transduced back into "sound". At the speaker, sound is
created when a electromagnetically-driven diaphragm or crystal produces
corresponding sound waves in surrounding air .
turn of the last century Alexander Graham Bell built what was probably
the world's first optical transducer of sound waves. He called it a
"photophone". Instead of translating sound into electrical
signals, Bell built an apparatus that turned sound waves into audio
frequency pulses of light. He also built "detectors" that
would convert audio frequency pulses of light into electrical signals
that could then be converted into sound. To construct my audio
microscopes I also used optical detectors and specially illuminated
stages and microscope slides that allow only light reflected from the
surfaces of specimens to enter the objective lens of microscopes . These
optical signals are then transduced into electrical signals via detectors
mounted on the microscope eyepiece. The electrical signals are subsequently
routed through more or less conventional audio equipment so that they
may then be perceived as sound in the ear/brain of the user/observer.
stages of this work I was surprised to find a wide range and diversity
of information in the microacoustic world. At lab we find organisms
on almost a daily basis that we have never seen or listened to before.
We therefore now routinely listen to organisms for the first time. Different
organisms make different sounds in the way that say, the sounds of horses
are perceived as different than the sounds of sheep. My experiments
with spectrum analysis tend to reinforce that notion. I found that slightly
different acoustic signatures corresponded to slightly different species
of microorganisms. Paramecium multimicronucleatum for instance, has
a slightly different audio signature than Paramecium caudatum. The signatures
of a given species however tend to be uniquely distinct to that species.
So as it turns out, the two plants of the same species must indeed "sing
the same song", unless perhaps the Ecuadorian brujo knows of some
exceptional organism unlike those we have observed to date. "