he modern trumpet acquired its familiar form in the early 1800's. In the 1990's, a classically trained trumpet player named Ben Neill gave the instrument a makeover. The result of Mr. Neill's tinkering was the mutantrumpet, a bulked- up version of a traditional horn, with a trio of bells, six valves instead of three and a trombone-like slide attached to the underside.

What makes the instrument contemporary, though, is its electronic dimension „ switches, pickups and wires that plug into a laptop computer outfitted with sound-control software. "I was trying to take acoustic sound and colorize it," Mr. Neill said. (Samples of Mr. Neill's work can be heard at www.benneill.com/recordings.html.)

Mr. Neill is among a handful of musicians trying to bring spontaneity and showmanship to live electronic music. When Mr. Neill developed the mutantrumpet, most electronic instruments were controlled by electric drum pads or musical keyboards. Those have been replaced by the computer keyboard as personal computers have gained the processing speed to handle digital audio, and software packages have been developed to exploit that power.

To those who grew up watching musicians perform using traditional instruments, programmed electronic shows often seem bloodless. "There's a whole laptop performance trend today," Mr. Neill said, "and it looks like the guy is typing a letter while he's onstage."

For Mr. Neill and the other inventors, their devices allow them to make live electronic performances exciting. In addition, while many people have created experimental electronic devices that produce random sounds, these inventors have constructed instruments whose sounds can be predicted and that require mastery, even virtuosity.

"There's a progression toward things being more and more automated," said Leon Gruenbaum, a 38-year-old classically trained pianist and clarinetist who usually performs jazz and his own music. "With automation," Mr. Gruenbaum said, "it's often made clear to you what was unique about the human component."

Mr. Gruenbaum, a New Yorker, set out to build an instrument that would allow him to play unusual sequences as fast as he could hear them in his head. "I was very much interested in creating something along the lines of a piano or a clarinet or any other instrument," he said.

He devised the whimsically named Samchillian Tip Tip Tip Cheeepeeeee (which can be heard at www.samchillian.com). It is an off-the-shelf Kinesis ergonomic keyboard modified and connected to a small black box with an embedded processor and MIDI circuitry, which is linked to a sampler that generates sounds. The instrument resembles the laptops that Mr. Gruenbaum and others criticize as contributing to banal live performances, but what makes the Samchillian special is that it is a relativistic MIDI controller. Unlike conventional instruments in which each key is associated with one note, the Samchillian's keys have been assigned to intervals. When Mr. Gruenbaum hits the comma key, for instance, he may produce a middle C. When he hits it again, he gets a C an octave higher. Hit a third time, it will generate C an octave above that.

Mr. Gruenbaum, who holds a patent on the device, programmed the left-bracket key to record a sequence of notes and play them back in specific patterns triggered by the musician, on the fly.

The instrument is also programmed to play in unusual tunings, using a 10-tone scale, for example, as well as a traditional 12-tone scale. In concert, Mr. Gruenbaum appears to be furiously tapping a computer keyboard strapped to his waist, and he sounds like a cross between Charlie Parker and Eddie Van Halen. Because he fears this might be visually dull, however, he often performs in costumes, including a cardboard-box hat with blinking lights and a clear plastic shower curtain worn as a shirt.

Mr. Gruenbaum began performing on the Samchillian in 1994 and has since become a regular onstage with Vernon Reid, the former lead guitarist for Living Colour. In 1998, he recorded a CD of his own music ("Foolifingo!") and is forming a band to record live performances for a new CD.

Mr. Neill's mutantrumpet converts sound into MIDI files, as the Samchillian does. Breath dynamics are measured at the mouthpiece with a pitch-to-MIDI converter, and several pressure-sensing pads translate touch strength with continuous-control MIDI converters. And as with the Samchillian, the mutantrumpet allows sequences to be triggered and manipulated in real time.

"The human body is very irregular," Mr. Neill said. "Machines are perfect. It gets interesting when you have a machine that can translate the irrational information from a body."

Mr. Neill mostly plays his own compositions. He lives in New York and performs at dance clubs and jazz and computer music festivals around the world. He has recorded several CD's and is working on a new one.

Sometimes, the new digital instruments require playing in a style that resembles performance art. Dan Brotman, a native New Yorker, built the shaka, a six-foot piece of metal across which he has strung eight piano strings, mounted on bridges and hooked up to electronic panels, and large guitar pickups that amplify and control the sound. Mr. Brotman, who performs in New York clubs under the name Urban Rhythm, plays the strings percussively, hitting them with mallets, sticks and guitar-type slides. He has used the instrument to record two CD's on the label, Futuremusic.

The shaka's technology is simpler than that of both the Samchillian and the mutantrumpet, but like his fellow innovators, Mr. Brotman is interested in creating a performance that excites audiences. "I'm trying to engage the crowd," he said.

All three musicians say it took them a few years to master a satisfying technique. Despite the learning curve, all three have also been asked about building copies of their creations for other musicians.

"I'd like to see other people playing the Samchillian," Mr. Gruenbaum said. "Jimi Hendrix did things with an electric guitar that Les Paul never thought of. I'd love to see what somebody else could come up with for the Samchillian that I would never think of."