PALO ALTO, Calif.—An expectant hush fell over the audience of 120 people as the director of the chamber ensemble, Ge Wang, came out and asked them to turn off their cell phones. The seven other musicians, dressed in black, filed in and took their positions in a circle.

The conductor raised his hands. A low droning sound arose, as if the chamber ensemble were tuning. Then the musicians began to swing their arms in wide circles, creating rising and falling waves of electronic sound.

The Stanford Mobile Phone Orchestra's performance on Thursday used the most unusual of instruments: Apple iPhones amplified by speakers attached to small fingerless gloves.

Sometimes the sounds were otherworldly. Sometimes, they mimicked raindrops, bird songs or freeway traffic. In one piece, two performers blew into their phones to stir virtual wind chimes. In another, the instruments took on personalities based on the pitch, volume and frequency of the notes played—as if the musicians were flirting, teasing and admonishing each other.

And gradually, the audience disobeyed instructions, pulling out their own iPhones and iPods to record the performance.

From the earliest days of the iPhone, applications that mimic musical instruments have topped the download charts. But the Stanford Mobile Phone Orchestra, with its avant-garde compositions and electronic renditions of popular songs like Led Zeppelin's “;Stairway to Heaven,”; is trying to push the frontiers of the four-decade-old field of computer music.

While computer music composers once spent hours programming giant mainframes to synthesize a single sound, advances in hardware and software have brought powerful and easy-to-use music tools to personal computers and now, to smartphones.

Wang, the assistant professor of music who leads the two-year-old Stanford group, says the iPhone may be the first instrument—electronic or acoustic—that millions of people will carry in their pockets. “;I can't bring my guitar or my piano or my cello wherever I go, but I do have my iPhone at all times,”; he said.

“;It is too early to make any judgment on”; cell-phone ensembles, said Paul Lansky, a composer and professor of music at Princeton who was a pioneering figure in computer music but recently abandoned the field to focus on traditional instruments. “;You can make great music with a rubber band and terrible music with a Stradivarius violin.”;