… or so I’ve heard

Last week we heard some interesting things at the lecture, as is to be expected when the topic was hearing! 🙂 We learned that the tonotopic (i.e. cochleotopic) organization of auditory cortices resembles that or visual cortices, i.e. different information (sound frequencies) are handled at different locations in the brain, even if not in the region described in Figure 11.27 of the course book, which, we learned, has macque tonotopic organization pasted on human brain… Also, the dorsal and ventral signal processing paths, the “where and what” processing streams, respectively, are analogous to those of visual data processing.

We also discussed, how the brain needs to calibrate auditory location spotting with the help other senses, and how it takes time. This is in accordance with my own observation that young kids do not seem to be able to make sense of directional auditory information, which gives you an edge playing hide-and-seek – now need to be quiet when it’s your turn to run and hide. It would be interesting to test if, by altering the shapes of my own pinna sufficiently would result in the loss of directional hearing. Pulling my ears didn’t seem to suffice and produced traumatic memories from my own childhood (of exceeding my limits and being gently led back within bounds by my ear flaps). 😉

I found it very fascinating how clever engineering there is in in the ear, how the signal is amplified 20-fold, and how there are also safety mechanisms that protect the ear against too loud sounds. If there’s room for improvement, I’d vote faster protection mechanisms as there is a delay before the muscles that protect the hearing contract, as I’ve had the opportunity to learn firsthand. I wonder if some are more prone to develop hearing loss exposed to the same information and whether it’s due to the effectivity of the protective mechanisms or something else? I have some dips in the frequency band along with tinnitus, whereas some of my friend do not seem to suffer from such problems despite, even if they have run to more gigs without any hearing protection than I with earplugs.

The audiovisual integration part was very illuminating, the illusion of hearing “baa” as “faa” was very strong coupled with the visual data. I wonder if I can use this as an excuse the next time I fail to understand what my wife says: “ The visual cues very conflicting, dear, I got confused!”

Posted by Tapio Saarinen

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