Via Scientific American…  It’s not only our brains that make us stand out from the rest of the critters here on planet Earth.  Brains actually receive a lot of pre-processed input.  Turns out our auditory system has a few neat tricks of its own too…

Why Dogs Don’t Enjoy Music

Anyone with normal hearing can distinguish between the musical tones in a scale: do, re, mi, fa, so, la, ti, do. We take this ability for granted, but among most mammals the feat is unparalleled.

This finding is one of many insights into the remarkable acuity of human hearing garnered by researchers at the University of California, Los Angeles, Hebrew University of Jerusalem and the Weizmann Institute of Science in Rehovot, Israel, reported in January in the journal Nature.

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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.

The vexing question is: Why? 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. These results suggest the fine discrimination of sound is not a necessity for survival.

More likely, the researchers speculate, humans use their fine hearing to facilitate working memory and learning capa­bilities, but more research is needed to explore this puzzle.

I have a strong hunch about that.  It isn’t memory and learning.  It’s communication.  Speech.  Try this sometime while listening to people around you chatting: try to ignore the words and just listen to the sounds of the voices as if you were listening to birds, or dogs or some other animals.  Humans have an Amazing range of vocalizations.  You think birds are good at it, but compared to humans birds are johnny one-notes.  Think of how much information is conveyed by tone of voice alone, in a conversation. 

Consider the sentence "The cow jumped over the moon".  A human speaking those words could convey astonishment or indifference or anger or fear simply by how they inflect the speaking of that string of words.  Just by slightly changing the inflection on the word "moon" you can change the sentence from a statement into a question.  It’s not just cadence.  It’s tone.  The better you can decode tone, the better you can tell what other people mean…how they feel…the better you can grasp what is being said.  And not only that, but the greater becomes the potential bandwidth of communication.  Because now information can be carried by both words and tone of voice.

Tone is the first language we have.  Human infants don’t do words.  They do coos and gurgles and squeals and cries.  A human sitting not far from a baby knows exactly how it’s feeling by all the little non-verbal vocalizations it’s making.  Is it content?  Is it delighted?  Is it curious?  Is it upset?  Does it need its diapers changed?  It needs to tell you these things and it can’t if it has to use words it hasn’t had time to learn yet.  But as we grow older, we don’t discard the language of tone.  In fact, it grows and develops along with us.  We learn to use it better…more deftly…just like we do our verbal languages.  How much is conveyed by lovers to one another, simply by a sigh?  And the longer a couple has been together, the more intimately they learn each other’s tone signals.  Like music, how the words are spoken goes right to the heart.

That’s why we evolved the more highly attenuated detection of tone.  It’s a communication thing.  The bigger brain needed it.  Words alone weren’t enough.  And I’ll bet this is why music affects us so profoundly, yet so irrationally.  Recall this from the article… 

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.

Music isn’t pure tones though.  Not even minimalist scores like those of Philip Glass.  A gathering of instruments in an orchestra, or even a single instrument playing a melody all by itself, produces a complex layering of tones that I’ll bet hits those neuron in just the same way.  It Is communication, but a different kind.  It’s communication that goes right past the logical analytical brain with its ear for words, to the heart, which listens to tones.  Tone was the first language.

The stereotype of our pre-human ancestors is that they communicated in simple grunts and barks.  Perhaps.  But even without language yet, those vocalizations may have carried a lot of information in them simply by tone alone.  Language evolved from those vocalizations, and gave them more precision, because the growing brain needed that.  But as our capacity for language developed and grew, so did our capacity to decode tone, because that was also a channel of communication.  But they’re different channels.  The logical rational brain likes words.  The emotional intuitive brain responds to tone.  When interacting with others, the one who can decode both those things best has a big advantage. 

So Orpheus probably didn’t tame the savage beasts by the sound of his lyre, because the beasts are mostly tone deaf.  But the beast within…yeah.  Absolutely.  Here’s an experiment: Humans that are tone deaf, or who have difficulty decoding tone…how well do they interact socially?

[Edited a bit more then a tad…]