MELISSA BLOCK, HOST:
This week, a book called "The Universal Sense" arrived in book stores. It caught our attention because it's about the medium that we work in: sound. In it, author Seth Horowitz explores the ways everyday sound affect us. He's an auditory neuroscientist who contends that sound is not just part of our world, it makes our world.
SETH HOROWITZ: Sound and the mind are very, very intricately linked, and yet we almost never pay attention to sound. Sound is always there. It's our early warning system. It's also our emotional driver. It's our attentional driver. Everything you hear has some kind of an impact on you and changes how you respond to the rest of the world. So since sound provides context, it's operating in the back and is able to give us the basis for a lot of very, very complex cognitive responses.
(SOUNDBITE OF CAT PURRING)
HOROWITZ: This first sound is something that - unless you really hate cats - it's an extremely comforting sound. It's just the sound of my particular cat, named Bluto, purring.
(SOUNDBITE OF CAT PURRING)
HOROWITZ: And it's a very, very comforting sound. But if we change it...
(SOUNDBITE OF CAT PURRING IN HIGH SPEED)
HOROWITZ: ...the sound of angry bees is one that gets right into your brainstem. But here's the trick, that cat purring sound...
(SOUNDBITE OF CAT PURRING)
HOROWITZ: ...which was so comforting, and the bee sound, which was so instantly fearful...
(SOUNDBITE OF CAT PURRING IN HIGH SPEED)
HOROWITZ: ...are the same sound, except for one or two little things. The sound of the angry bees that you just heard is actually just a cat purr sped up in chorus to make it sound like there's a whole bunch of them. So by taking a single parameter of a sound, the modulation rate, and just shift it, you can change the entire emotional response that you have to a sound from something that's comforting or relaxing to something that makes you want to get out of the area really quickly. And this works all the time. Another example just to show how important context is, it comes with this next sound.
(SOUNDBITE OF MEALWORMS EATING A BAT CARCASS)
HOROWITZ: It sounds like the sound of rain falling on a roof, and it brings up associations. You listen to the sound of rain on a roof, and it's a lazy afternoon and nothing particularly going on, and you can either be a little bit melancholy or even just be relaxed, realizing there's nothing really else going on, the environment is fine, until I tell you that that's not actually the sounds of rain on a roof but is in fact the sounds of mealworms eating a bat carcass.
(SOUNDBITE OF MEALWORMS EATING A BAT CARCASS)
HOROWITZ: And your brain just went from relaxed rain on the roof to eww in about 300,000ths of a second. Emotion is one of the most complicated things that the brain has to carry out, and one of the most important drivers of emotion is sound. And the reason it's so important is because it works underneath our cognitive radar.
BLOCK: That's Seth Horowitz, an auditory neuroscientist at Brown University. He's author of the new book "The Universal Sense." Transcript provided by NPR, Copyright NPR.