dB
Stapes: a small piston driving the oval windowMalleus and incus: a shared pivot with a 1.3:1 lever ratioTympanic membrane (about 55 mm²) and round window membraneTwo front dials: pressure at the eardrum and in the inner ear, on the same 0–140 dB scaleVestibule, cochlea and cochlear nerve: brightness represents a wave; particles represent neural signals (schematic)The malleus–incus lever multiplies the force on the eardrum by 1.3 and concentrates it on a footplate with about 1/17 of the area (3.2 mm²). Oval-window pressure is about 22 times the eardrum pressure, a gain of about 27 dB in an ideal transformer. Measured gain varies with frequency and is roughly 20 dB near 1 kHz. Without this transformation, most sound energy would be reflected at the air–fluid boundary. Because fluid is nearly incompressible, inward footplate motion pushes the round window membrane outward. Actual amplitudes are measured in nanometers; motion here is enlarged and scaled to logarithmic sound level. Only the outer bony labyrinth is shown, with internal fluid spaces omitted. The oval and round windows lie behind the vestibule and cochlear shell in this view; rotate the 3D model to see them. The tympanic membrane attaches along the malleus handle. Fibers from each cochlear turn enter the translucent modiolus, then leave its base as a cochlear nerve bundle descending to the support socket. The socket supports the model; it is not an anatomical nerve ending. Softer sound increases firing intervals and makes particles sparser; particle speed stays constant.Brightness traveling from the cochlear base to apex represents a basilar-membrane traveling wave. Particles along nerve fibers represent electrical action potentials, not actual light. Louder sound increases brightness and the highlighted area (schematic). The light 2D theme uses darker ink for emphasis. Wave speed is independent of sound level; particle frequency eventually saturates. Speed, brightness, spread and frequency are illustrative, not a detailed physiological simulation. The 3D display is mirrored to match the initial 2D view and does not establish left- or right-ear orientation.