WASHINGTON — For science-fiction buffs, it's probably a common-sense solution. Two months after arriving in Iraq, a second lieutenant with the 16th Military Police Brigade was handed the Phraselator, a hand-held device that promised to digest his English phrases and produce a prerecorded Arabic translation with an Iraqi accent.

But after a brief test last year, the soldier gave up the gadget, deciding that, while helpful in some instances, it wasn't useful to his unit, which conducted raids and provided convoy security. Even such simple phrases as "What is your name?" are spoken differently in Fallujah than in Baghdad, he found. "This may have been the reason why many of the Iraqis ... did not appear to understand the Arabic phrases and words" stored in the device, according to a report prepared for the Army.

An Annapolis, Md., firm, VoxTec International Inc., developed the device and said it has steadily made improvements. But the goal of having a machine replace a human interpreter remains elusive, and the military is mounting a multimillion-dollar campaign to find a more capable successor, one that can translate both sides of a conversation, from English to Arabic and vice versa.

"What people would really like is that 'Star Trek' universal communicator, but it doesn't exist yet," said Lynne McCann, former chief of the Army Foreign Language Proponency Office. "That would solve everything."

The stakes are high for the military, which suffers from a shortage of interpreters and has had to rely increasingly on contractors — 6,500 in Iraq and 1,500 in Afghanistan. It can be a dangerous job. Of the 648 contractors killed in Iraq since the war began in March 2003, 153 worked for the division of L-3 Communications Corp. that currently holds the linguist contract, according to Labor Department figures.

Battlefields often turn into impromptu laboratories for new technologies — with mixed results. VoxTec, which was a unit within Marine Acoustics Inc., was asked to rush production of its Phraselator, then a single prototype, shortly after the Sept. 11 attacks, said Ace Sarich, the company's vice president of development. The device is about the size of a large personal digital assistant and is programmed with about 700 Arabic phrases that can be recalled after it "hears" the equivalent English phrase or a soldier chooses a sentence from a text list on the device.

While VoxTec continued to improve the device, the military began testing a device made by a California company, Integrated Wave Technologies Inc. It had developed a similar hands-free version of a translation machine that fit into an ammunition pouch, allowing soldiers to say key phrases that are then turned into full Arabic sentences.

"You say 'house search' and then it will say in Arabic: " 'We're here to search your house. Please stay in this room. Do you have any weapons?' " said Tim McCune, the company's president.

Over the past few years, Integrated Wave Technologies has produced 1,300 of its machines and VoxTec has made 5,000 devices. They cost about $2,500 to $3,000 apiece. Neither product, however, proved robust enough to replace human interpreters. What soldiers really needed, the military decided, was to have a conversation with the people they encounter, not just give orders.

"In years past, there wasn't a great need for the individual soldier to speak a foreign language to do his mission," said Wayne Richards, branch chief for technology implementation at U.S. Joint Forces Command. But in Iraq and Afghanistan, soldiers are increasingly interacting with civilians, giving advice at checkpoints or guidance during home searches, he said.

So the Pentagon turned to the Defense Advanced Research Projects Agency to enlist some technology powerhouses, setting aside $20.8 million this year for translation technologies. Military officials said they do not expect the automated devices to replace human interpreters but to augment them.