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Comment by DigiDigiorno | Hacker News Reader

"[Coral larvae] don't have ears but somehow they're attracted to healthy reef sounds," he said.

"Maybe they can sense the vibrations with their cilia [tiny hair-like appendages], but we don't know.".

This sounds like more of a philosophical question, but is there a difference between hearing and sensing vibrations? Is there a certain level of signal processing required for hearing? Like, I can sense vibrations with my fingers, but I wouldn't call that hearing.

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Here is a dry land analogue. [1] Tree roots grow towards the sound of water.

[1] https://ec.europa.eu/research-and-innovation/en/horizon-maga...

It's physiological rather than philosophical. Auditory stimuli are sensed through your ear and tactile through the somatosensory system (in humans). There's some crossover in the frequencies both can detect.

There's also some potential crossover in how these may be perceived. For example, experiments which show you may in fact be able to 'hear' through your fingers; https://www.nature.com/articles/s41598-022-06855-8.

> Like, I can sense vibrations with my fingers, but I wouldn't call that hearing.

Touch is a powerful sensory input and some folks who suffer from deafblindness can truly “hear” spoken words through touch.

I tried to do that once. I almost could make out what they were saying, but I couldn't quite put my finger on it.*

*ᴵ ᵃᵖᵒˡᵒᵍᶦᶻᵉ ᶦⁿ ᵃᵈᵛᵃⁿᶜᵉᵈ ᶠᵒʳ ᵗʰᶦˢ ˢᵗᵘᵖᶦᵈ ʲᵒᵏᵉ

There’s something like the human audible spectrum similar to the human visible light spectrum.

We know for a fact that animals see and hear differently than we do by observing parts of the spectrum that humans cannot.

Interesting, Maybe it has to do with the extra analyses that the brain performs on hearing. What I hear is not the raw vibration but a amonst other things a fourier transform of it. i hear a distinct pitch. The brain uses the harmonic overtones of sounds to group them together. When I feel vibrations with my finger I just feel slower or faster vibrations.

By the way, sometimes I hear a sound so low that I am confused whether I hear or feel it.

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