Chapter II · The Arc of a Session
Plate 01 · Bone conductionEd. of 24
speed sound travels through dense bone, vs. ~343 m/s through air
Your skeleton hears the fork before your ears do
Applied to a joint, a tuning fork's vibration reaches surrounding tissue through bone almost instantly — arriving as sensation in the body well before it registers as sound in the ear.
Plate 02 · Vascular responseEd. of 24
shear stress at which endothelial cells trigger nitric oxide release
Blood vessels respond to vibration the way they respond to exercise
The same mechanical signal that tells endothelial cells to dilate vessels during a workout can be produced by a fork's mechanical pulse against the skin, which is why forks are placed at sites of restricted circulation rather than waved at random.
Plate 03 · Instrument scienceEd. of 24
the musical designation stamped on the Otto 128 tuning fork
The forks are tuned to the same C as a piano's lowest note
John Beaulieu, a research psychologist and musician, chose that octave of C in the 1980s after studying how weighted forks — unlike standard unweighted ones — sustain a slow, low pulse long enough for tissue to entrain to it, which raises the next question: what does entrainment actually mean at the cellular level.