jonny (good kind)This is pretty cool - reptile found that can sense low frequency sound with the saccule: https://doi.org/10.1016/j.cub.2024.09.016
(I'll edit with a direct PDF link in a sec)
Hearing evolved in fishes, where the swim bladder as a big resonant cavity reached out to touch the vestibular organ and kinda vibrate it. That is only good for low frequencies, so to some degree the history of the evolution of audition has been a quest for higher frequencies - thinning out a tympanic membrane, the evolution of the inner ear by stealing jawbones, the enlargement of the brain case to close off the middle ears (our eustachian tubes are vestigial remnants of what used to be an "open passageway" from ear to ear).
Sound is a veridical readout of the matter that produces it, so different frequency ranges contain different kinds of information, and small things including textures and material composition are only audible with higher frequency ranges. Low freqs are important too, but especially with the transition to land, needing to handle the impedance mismatch between fluid filled bodies and open air makes an organ that can hear a wide range of frequencies challenging.
So the cochlea gets all the attention as the auditory organ because its one of the most remarkably precise and Scientifically Magical organs out there, but the vestibular system is cool too. It's basically a bag of saltwater and rocks and when you jangle your head around the rocks touch little hair cells and tell you you're moving.
Because of its torrid history the auditory system is sort of a clusterfuck, but these researchers found direct projections from the Saccule through to the auditory midbrain. They're sensitive to vibration (through a surface), not sound (through the air), but still go to auditory system, so while we have no idea what the perceptual reality is like, i dont think it is unfair to say that the geckos "hear vibration."
PREreview
Tirial
T. T. Perry