What it means to hear

Most everyone who hears their recorded voice for the first time has the same reaction: That doesn't sound like me.
The new exhibit ``Listen: Making Sense of Sound,'' which opens Saturday at San Francisco's Exploratorium, explains that phenomenon and, in the hands-on style this museum has pioneered, shows why in a most unusual way.
Visitors at the stop called ``Sound Bite,'' just one along a 55-exhibit, 5,000-square-foot path of auditory explorations, bite down on a plastic straw surrounding a metal bar.

Suddenly, Hawaiian house music or American Indian hip-hop floods into their ears, conducted imperceptibly along the jaw bone, the same way the bone transfers your own voice.
When you talk, you hear your voice through your ears and through your jaw bone. But when you hear it on tape, the sound comes only through your ears, explains Thomas Humphrey, a former particle physics scientist at the California Institute of Technology's Pasadena campus, who was one of the scientists and artists who spent three years putting together this ambitious show.

The exhibition was the result of the love of music on the part of many of the scientists and artists at the museum, he says. ``It was just a natural,'' he adds.
Artist Mary Elizabeth Yarbrough created Sound Bites from an art piece she once made.

She had to navigate some tricky concerns about safety for an exhibit that is as popular with children as adults.
``I worried about how I could get anyone to bite anything in a place that is like a Petri dish for germs,'' she says. Plastic straws were the solution, though she would still like to find more environmentally friendly straws.

She spiced up the experience with strains of music she figures most people never have heard.
The theme is similar at another exhibit, Pamela Winfrey's giant jukebox, programmed with music she hopes people haven't heard before, including some made by indigenous tribes and some by lesser-known Bay Area musicians, such as guitarist Fred Frith.
``It's like no other juke box,'' she says, playing a West African tune that celebrates female circumcision.

``For them, it's a big day in a girl's life, and it's joyful and a cause for celebration, even though in our Western mind it isn't,'' she adds.
In a place exploring noise, sounds and music, there is one exhibit that celebrates silence, and makes a competition of shhhhhush.
Inspired by games she made up as a kid imagining burglars coming to her house, Yarbrough created an exhibit with microphones hidden in a path of gravel.

The signals from them display numbers, or scores, to show how much sound is produced by each footstep. The object is to go across the room creating as little noise as possible. The lowest score wins.

You will be surprised at how loud you are, even when you think you are not. And almost everyone who tries wants to repeat the process to improve the score, Yarbrough says.
We all know about optical illusions.

What about auditory ones?
There are plenty of ear teasers here.
One exhibit creates an auditory hallucination, as two syllables of a word are split between stereo speakers and repeated for 45 seconds, until a word that once seemed familiar becomes unrecognizable.

In another, a familiar story is read, but none of the words are right. You can't help but laugh as your brain miraculously pieces together and translates a reading of ``Ladle Rat Rotten Hut'' into ``Little Red Riding Hood.''
And just after congratulating yourself for translating that, you enter another exhibit that will have you doubting your auditory dexterity.

You sit under a hair dryer, while interesting overheard conversations are streamed into both ears, as if you were in a salon or restaurant. In one ear, you get the conversation of a man breaking up with his girlfriend after having an affair with her friend. In the other, you hear a woman who has found a finger in her food.

This could be a voyeur's heaven, but as the conversations get more intense, the brain seems to short-circuit while trying to keep up with both.
Seeing is sometimes said to be believing, but there's a sign in the museum that proves seeing is only the brain's best guess.
After a few hours here, you won't believe everything you hear, either.

You will shake your head in wonder at the unexplored possibilities and limitations of a sense we too often take for granted.
Some of the exhibits are designed to be heard online through headphones. Check them out at .

Where: Exploratorium, 3601 Lyons St.