loading the head — 109,000 triangles of scanned bone and skin…

ACT 01 · SOUND — a wave of pressure reaches the ear

Sound is air being squeezed and let go, passed along from molecule to molecule at about 343 metres a second. Nothing travels from the source to you but the squeeze itself. A 1,000 Hz tone is a thousand of those squeezes a second, each 34 cm apart. The quietest one a young ear can hear moves the air's pressure by twenty millionths of a pascal — about one five-billionth of the atmosphere around you. The head and the skull here are a real scan; tap a tone to hear it and watch the air.

  • SCAN Skull bones, skin and the right auricle: BodyParts3D 4.0 (DBCLS), one adult male, in their measured places.
  • FACT 0 dB SPL is 20 µPa; speed of sound 343 m/s in air at 20 °C. The points show the air's compressions and rarefactions, slowed down and exaggerated.
sources
  • BodyParts3D 4.0, © The Database Center for Life Science (DBCLS), CC BY-SA 2.1 JP — skull, skin, right temporal bone, auricle.
  • Sotomayor M., Weihofen W.A., Gaudet R., Corey D.P. Structure of a force-conveying cadherin bond essential for inner-ear mechanotransduction. Nature 2012;492:128–132. PDB 4APX (RCSB PDB, CC0).
  • Greenwood D.D. A cochlear frequency-position function for several species — 29 years later. J Acoust Soc Am 1990;87:2592–2605.
  • Erixon E. et al. Variational anatomy of the human cochlea: implications for cochlear implantation. Otol Neurotol 2009;30:14–22.
  • von Békésy G. Experiments in Hearing. McGraw-Hill 1960 — travelling waves on the basilar membrane.
  • Pickles J.O. An Introduction to the Physiology of Hearing, 4th ed. 2012 — middle-ear transformer, hair-cell numbers, endocochlear potential.
  • Spoendlin H. Innervation densities of the cochlea. Acta Otolaryngol 1972;73:235–248.
  • Kazmierczak P. et al. Cadherin 23 and protocadherin 15 interact to form tip-link filaments in sensory hair cells. Nature 2007;449:87–91.
  • Corey D.P., Hudspeth A.J. Kinetics of the receptor current in bullfrog saccular hair cells. J Neurosci 1983;3:962–976 — gating springs, microsecond opening.
  • Pan B. et al. TMC1 forms the pore of mechanosensory transduction channels in vertebrate inner ear hair cells. Neuron 2018;99:736–753.
  • ISO 226:2003 Acoustics — Normal equal-loudness-level contours (threshold of hearing).
  • NIOSH. Criteria for a Recommended Standard: Occupational Noise Exposure. DHHS (NIOSH) 98-126, 1998.
  • CDC National Center for Environmental Health. What Noises Cause Hearing Loss? (dBA ranges of everyday sounds).
  • WHO. World Report on Hearing 2021; WHO 2015 'Make Listening Safe'; WHO–ITU H.870 Safe listening devices and systems (2019, rev. 2022).
  • Corwin J.T., Cotanche D.A. Regeneration of sensory hair cells after acoustic trauma. Science 1988;240:1772–1774.
  • Kujawa S.G., Liberman M.C. Adding insult to injury: cochlear nerve degeneration after 'temporary' noise-induced hearing loss. J Neurosci 2009;29:14077–14085.

Geometry: BodyParts3D, © The Database Center for Life Science, licensed CC BY-SA 2.1 Japan; the derived meshes (public/anatomy/ear.glb) are re-shared under the same licence. BodyParts3D has no middle or inner ear, so the canal, eardrum, ossicles, cochlea and canals are modelled from the dimensions above. Atoms: RCSB PDB 4APX, CC0.

EDUCATION ONLY Education only — not medical advice and not a hearing test. If you notice ringing, muffled hearing or sudden hearing loss, see a doctor or audiologist; sudden loss in one ear is urgent.Not medical advice, not a hearing test. Keep the volume low.