Booming sound waves halfway around the world, a team of U.S. scientists hopes to resolve one of the hottest scientific debates of the age: Is global warming fact or fantasy?

The team will set sail soon for a volcanic island near the icy fringe of Antarctica to begin a series of underwater tests which, if successful, could develop into one of the most ingenious and closely watched global experiments in history.The expedition of oceanographers and marine biologists plans to embark on two research ships from the west Australian port of Fremantle on or about Jan. 9 and drop anchor some two weeks later off Heard Island, a remote and uninhabited Australian territory in the south Indian Ocean.

There the scientists will lower a giant loudspeaker into the sea and, for 10 days, transmit intermittent low-frequency signals, which they hope will be audible to highly sensitive listening devices located at 17 or 18 monitoring points around the globe - some as far as 10,000 miles away on both east and west coasts of North America.

At this stage, the Heard Island experiment is no more than a test to see if sound can be transmitted clearly over vast stretches of ocean. If successful, however, scientists involved with the project say it could develop into an international cooperative effort to prove or disprove that the oceans are growing warmer.

The entire project hinges on the fact that the speed of sound increases with the temperature of the medium through which it travels - the inference being that any warming of the oceans would cause a slight but measurable shortening of the time it would take for the Heard Island sounds to reach the monitors. The farther sound travels, the easier it is to spot any changes in speed and the more accurately they can be measured; hence the extensive range of the experiment.

As warming would be gradual, scientists say it would take at least 10 years to glean reliable data.