“…the forest throbs with the water-blood heartbeat of twigs… On sun-happy
branches, systole and diastole surge and draw back, the forest’s subsonic hum.”

I recorded microscopic variations in the width of a maple twig. Daily, the twig’s diameter grows and shrinks as water flows through its vessels. I turned this slow “pulse” into sound by converting the diameter of the twig into a note played on an electronic piano. The fatter the twig, the higher the note. In the changing pitch of the piano you can hear the twig’s daily cycle. Many thanks to Jonathan N. Middleton and his team at Eastern Washington University whose MusicAlgorithms I used for the data-to-sound conversion.

A multi-day sequence, April 28th to 17th May, one note for every two hours, played on chromatic scale in C. The twig is full of water at midnight (high notes), then shrinks after sunrise as water starts to flow and draws the twig inward (lower notes). The pitch also increases as the days go by because in addition to its daily water-driven pulse, the twig is adding new wood, getting wider:

One 24 hour period (May 5th, midnight to midnight), one note for every 15 minutes of the day:

The same sequence, but with one note for every 15 minutes. I cranked the tempo to 240 beats/minute. Because some hours are sunnier than others, the change in pitch is not perfectly smooth:

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