… The study revealed that groups of exquisitely sensitive neurons exist along the auditory nerve on its way from the ear to the auditory cortex. In these neurons natural sounds, such as the human voice, elicit a completely different and far more complex set of responses than do artificial noises such as pure tones. In this mixed environment humans can easily detect frequencies as fine as one twelfth of an octave — a half step in musical terminology.
… Bats are the only mammal with a better ability to hear changes in pitch than humans do. Predatory species such as dogs are not nearly as sensitive-they can discriminate resolutions of one third of an octave. Even our primate relatives do not come close: macaques can resolve only half an octave.
– from Why Dogs Don’t Enjoy Music by Sandy Fritz in Scientific American (Oct, 2008)
In comments, reader kieryn makes the obvious response to the question, which she quotes from the article, of why we are so sensitive to variations in sound:
“The vexing question is: Why? [various other animals don't have our ability] These results suggest the fine discrimination of sound is not a necessity for survival” That’s so beside point of evolution. It’s like saying breathing underwater is not necessary for survival because some creatures can’t. However, if you live underwater (like a fish) then clearly the ability to breath underwater is going to give you an advantage. This is not about necessity, it’s about an evolutionary advantage. Clearly, given how social humans became and how we started to use language and how our brains developed the ability to use information such as the quality or pitch of sounds to cognitively model objects in our environment, it’s easy to understand why this ability gave us so many advantages over our competitors.
We are “exquisitely sensitive” to auditory input — signals — but we still aren’t perfect at figuring out what those signals mean.
For example consider poor Otto the octopus, trying to get his handlers to give him a break:
Staff believe that the octopus called Otto had been annoyed by the bright light shining into his aquarium and had discovered he could extinguish it by climbing onto the rim of his tank and squirting a jet of water in its direction.
The short-circuit had baffled electricians as well as staff at the Sea Star Aquarium in Coburg, Germany, who decided to take shifts sleeping on the floor to find out what caused the mysterious blackouts.
A spokesman said: “It was a serious matter because it shorted the electricity supply to the whole aquarium that threatened the lives of the other animals when water pumps ceased to work.
“It was on the third night that we found out that the octopus Otto was responsible for the chaos.
“We knew that he was bored as the aquarium is closed for winter, and at two feet, seven inches Otto had discovered he was big enough to swing onto the edge of his tank and shoot out a the 2000 Watt spot light above him with a carefully directed jet of water.”
Director Elfriede Kummer who witnessed the act said: “We’ve put the light a bit higher now so he shouldn’t be able to reach it. But Otto is constantly craving for attention and always comes up with new stunts so we have realised we will have to keep more careful eye on him – and also perhaps give him a few more toys to play with.
“Once we saw him juggling the hermit crabs in his tank, another time he threw stones against the glass damaging it. And from time to time he completely re-arranges his tank to make it suit his own taste better – much to the distress of his fellow tank inhabitants.”
– Otto the octopus wreaks havocfrom Telegraph.co.uk (Oct 31, 2008) found via Pharyngula
I totally sympathize with Otto. We (Otto and I) are not violent by nature, but if you don’t listen to us, damnit, the water pistols are going to come out and somebody is going to get wet. As to the juggling of hermit crabs, we do admit to having a certain urge to show off, but aren’t we artists all juggling octopuses at heart?
The staff at the aquarium certainly “heard” Otto’s discontent but they ignored or failed to understand him. They didn’t get the message. They under-responded.
The other extreme of incorrect response to auditory input is over-response. For example, a few weeks ago, the following happened to me while I was in Krogers [US grocery store chain] doing the weekly food-and-stuff re-provisioning. As usual, I was in a zone; same up-one-aisle-down-another getting the same stuff, same people, same everything, my mind a thousand miles away, when I hear this little “beep-beep” — high, chirpy, exactly like the focus-lock beep-beep that my Canon cameras make. Instantly I, with no camera on my person, was perfectly focused … on the canned goods. Observing color, composition, lighting, and sharpness, all in an instant. I have no idea where the beep-beep came from; probably an alarm on another shopper’s digital watch, but my response was … kind of cool. I was instantly and fully there.
I could use such an personal beep-beeper to keep me focused and on-topic. Right now, for example …
[This post was partly provoked by a failed or misunderstood or ... who knows what? ... Photoshop joke of mine. The message was not gotten. Goes to show you should not play Photoshop jokes on people who don't use Photoshop.]
-Julie
