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Indianapolis Star Sounding off September 12, 2005 From the screech of a professor writing on a chalkboard to the melancholy of Tchaikovsky's Symphony No. 6, the "Pathétique," probably no human sense is imbued with more emotion and passion than the ability to hear. But why? What makes sound so important to the business of being human? Robert E. Novak, a clinical professor and director of clinical education in the audiology program at Purdue University, says we process sound on three levels:
Beyond that, Novak says, sounds are pleasant or unpleasant depending on where they fall on the wavelength. Think of that piece of chalk dragging across a board at the front of a classroom. That sound comes in at the most sensitive range of our hearing, which is between 2,000 and 6,000 hertz, said Novak. "When you get a frequency in that region that's already loud, that's going to be really uncomfortable," he said. Sound is a series of wavelike changes in air pressure; we hear and discern the slightest variations in frequency because of the ear's ability to amplify the sound. The frequency range for human hearing is roughly between 20 and 20,000 hertz -- the lower numbers are "low," thumping sounds like those from a car boom box, and the highest numbers are essentially whistling sounds. "The range is greater for sound than for sight," said Jim Hunter, a vice president of design engineering at Indianapolis-based Klipsch Audio Technologies, which makes both high-end consumer and commercial audio equipment. "The power ratio is in the millions-to-one," Hunter said. Sound is wave motion -- it gets weaker as it radiates from its source, just as light does. Sound also appears to change its frequency as the source moves relative to you, the listener -- that's the secret behind the "Doppler effect" when a fast-moving train passes you. Explaining sound as an aesthetic is even more complex and subtle -- one man's Tchaikovsky is another's Eminem. Some people think the sounds of childhood always are enduring-- and treasured -- just like the sight of a first Christmas tree, or the aroma from a freshly baked apple pie set out to cool. Some people adore the sounds of nature -- waves crashing onto the shore, autumn leaves rustling in the wind, the crunch of freshly fallen snow under a heavy boot. Maybe. Maybe not. The creak of a wooden step, especially if in a slowly rhythmic cadence, is a staple of horror films. He's got a knife! He's got a knife! Sound appreciation is cultural, too. Purdue's Bob Novak says Chinese opera always sounds high-pitched, even squeaky, to Westerners. One soothing sound probably is universal, though, says Novak. "When you think of a mother's voice to a baby, that pretty much is very intriguing to babies across cultures," said Novak. "That's pretty much universal."
If one picture is worth a thousand words, what's a sound bite worth?
We don't know, either, but we decided to record some favorite sounds.
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