Worm’s Eye View

The second iteration of our root/tree enclosure has been in place for several weeks and has seen more use than the first. Perhaps this is due to the increasingly warmer and sunnier spring weather? Perhaps it has something also to do with the configuration of the enclosure itself? A series of drawings for each iteration of the enclosure provides further opportunities to consider what it means to create an interior and exterior space, what it means to position ourselves in relationship to the tree. Critical to this analysis is the point of view of the drawing.  Four drawings for each enclosure were made, all done in parallel (isometric) projection, however the most compelling point of view in my mind, was the worm’s eye view.

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This point of view seems appropriate for the enclosures because it positions the observer looking upward into the tree, as you would be if you were seated in the enclosure itself. It also strengthens, lengthens and underscores the tree and the enclosure, and their presence, while humbling the viewer. The worm’s eye view offers a sensation of being embedded within the earth looking through transparent soil to the tree and the enclosure above. Perhaps root’s eye view is more appropriate for the context of our studio? At least one more set of drawings to add to the current two would make a more complete series, so I am thinking about the next iteration of our enclosure project and what that might look like…

Tree Listening

Another set of tests with listening to the trees today, this time using simpler microphones – two 27mm piezo discs (acoustic pickups). The simplicity of their design offers other possibilities for connecting them to the trees. I tried two different configurations today;  slotting them into spaces between the bark, and adhering them to a branch with two-sided tape. Having two of these microphones also allowed for recording in “stereo.” I inserted the microphones into the tree one on either side of one of our boreholes and began speaking into, blowing into, and prodding the borehole. (it’s best to listen to these files with headphones)

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I also tried adhering the microphones to two locations on one low-hanging branch. The left channel (ear) microphone was placed closest to the trunk and the right channel (ear) microphone was placed further out along the branch. I then began repeatedly bending the branch.

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The second recording marks a significant step in the tree listening experiments. Rather than generating a sound with an external device and recording that sound as it travels through the tree, the recording of the branch bending is the sound of the tree itself as it responds to an external stress. The result is much richer and the difference in location of the microphones is audibly detected. There is evidence to suggest that smaller plants (and perhaps trees?) produce an immediate electrical response when subjected to stresses such as having a leaf torn, or having stems shaken. If this holds for our oak trees, capturing that electrical variation and feeding it through audible output (vocoder, MIDI controller) might be one way to give a voice to the trees.

Traces

IMG_5713.JPGThe first iteration of the tree enclosure has been dismantled, but not without leaving its mark.

Keep an eye open for the next iteration.

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Tree Sounding

 

How do we gain access to tree-ness? How are symptoms diagnosed from within the inaccessibility of a tree–its history, its girth, etc? These are some of the broader landscape forensic questions we have been asking throughout the term.

This past week we worked with the German physicist, inventor, and tree expert Frank Rinn to begin to map the interior of a tree using sound.

Yup, sound.

Frank has invented and manufactures a system for sonic tomography–the measurement of a tree’s cross-sectional density by means of sound-waves. IMG_5407

With a girdle of 15+ sensors, the tree is sounded in a sort of arboreal perambulation–where each sensor is lightly tapped 5 times as the propagation time of the sound wave is  measured at each of the other sensors. The resulting measurement is a map of the speed of sound through the medium of the tree.

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Each vector in the chart to the left measures the relative time it took for the sound wave to reach a corresponding sensor. The resulting diagram of greens, oranges, yellows, pinks, and reds, is simply a visual coding of speed–with green being relatively fast, and red/pink being relatively slow (or nonexistent).

This set of measurement is then interpolated to form a density map on in the tomogram on the right. Here, a visualization of the wood density–and, perhaps, through experience in interpretation, strength–is charted in a communicable form.

As Frank is quick to point out that, while this tomographic system certainly communicates fundamental scientific information about the trees in question, this sort of imagining is fundamentally a political tool. In the politics of the visible, and in the politics of urban street-trees in particular, the ability to communicate the non-visible, the subcutaneous, allows urban foresters an immediate way to construct a slightly more informed landscape public.

At stake in this sort of measurement is the politics of diagnosis. Landscape is uniquely interpretable as a symptom: a symptom of ecological pressures, historical processes, and design intents. The traces of these (geo)histories, embedded as they are within the body of the tree, provide symptoms that can be diagnosed through a range of landscape forensic activities. Much of what we have been up to in this course is exactly this. Landscape forensics as method.

 

Listening to a Tree

Provoked by questions surrounding the nature of sound in/through/among trees, we completed our first auditory exploration on tree C7 in the allee. Carefully working through the layers of bark until we encountered the living matter of the tree, we carved a 4 inch square hollow in which to place our listening device. This device is an ElectroVoice Model 805 Crystal Contact Microphone, circa 1950 (incidentally and coincidentally,this exact model of microphone has apparently been used on trees before to record beetle movement!).

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The first tests frame the tree as a resonator, planting the microphone within the hollow and recording the output with a zoom mic. Using a mallet on the bark we circumscribed the tree with a series of taps moving first away from the mic and returning to it from the other side. This exercise produces a few new ways in which to draw/diagram the tree. The recorded audio itself (with some simple noise reduction applied) places us in the sonic space of the tree. The spectral frequency of this recording also allows us to understand the tree in a new way.

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What does the attack, decay, sustain, release profile of these mallet strikes tell us? Can the heartwood be read from the signal? Or does the variation simply indicate the difficulty in maintaining a consistent signal from point to point? Thirdly, the dance around the tree with the mallet serves as a diagram. Certainly much more can be mined from this first test. The next step will be to frame the tree as an articulator, listening for the sounds the tree itself produces, especially as it begins to wake from it’s winter slumber.