MILPITAS, Calif. — Long a niche specialty, high-end PC audio is working its way into the mainstream retail market, as the most recognizable names in multimedia add-in cards are releasing products to run high-quality sound and 3-D audio effects across the PCI bus.

Opposing salvos were fired this month. Creative Labs Inc. released a Sound Blaster Live! board, the first hardware for the Environmental Audio program Creative announced earlier this year, and Aureal Semiconductor Inc. (Fremont, Calif.) produced version 2.0 of its A3D technology, which was released on the Vortex 2 chip. Aureal's part will be available on a board from Diamond Multimedia Systems Inc.

Diamond, which is among the critical OEMs using Vortex 2, allied with Aureal in July to codevelop future generations of Diamond audio cards and releasing cards for Vortex 2.

The Aureal-Creative rivalry pits Aureal's technology and its early market-share lead against the franchise of Creative's Sound Blaster line of PC add-in cards. Aureal has grabbed the lead, but Creative and other competitors have banded with Microsoft Corp. to develop Environmental Audio as an extension to the Direct Sound API.

The rivalry intensified in February when Creative sued Aureal, claiming the patent assigned to the Vortex AU8820 part infringed on a patent held by Creative subsidiary E-Mu Systems Inc. Aureal has requested a summary judgement, a move which would settle the case before it hits trial court next month.

Still, the entrance of Creative to the 3-D audio game is encouraging to Aureal, because Creative's name power could help push sophisticated audio technology into the PC mainstream, said Toni Schneider, Aureal's vice president of strategic alliances. "The main thing for everyone is to make sure 3-D audio gets adopted into [game] titles," he said.

Creative this month began worldwide shipments of Sound Blaster Live!, a card based on the EMU10K1 audio chip developed by E-Mu (Scotts Valley, Calif.). The card is a pivotal piece of Creative's Environmental Audio platform, introduced at the E3 trade show in May, which the company hopes will become a standard for audio on the PCI bus.

Environmental Audio is largely the fruit of Creative's past acquisitions, incorporating wave-table synthesis technology from E-Mu and stereo speakers from last year's prize, Cambridge SoundWorks Inc. The combined technologies allow Creative to control sound from its origin as data bits to the actual playback over speakers, said Dana Massie, director of the E-Mu/Creative Technology Center (Scotts Valley).

E-Mu's 10K1 chip is the core of Creative's offerings and the driver for the SoundBlaster Live! card. Also, Creative is releasing its own set of Environmental Audio extensions, labeled EAX. Creative has been spreading the extensions through the industry freely and intends to make them an open standard, Massie said.

On the technology front, Aureal's Schneider claims its A3D technology has more sophisticated ways of creating a "room" sound than does Sound Blaster Live! Creative adds reverberations to match the surroundings — echoing or muffling sounds as appropriate — while Aureal goes further by doing the same for multiple rooms that might be off-screen but within hearing distance, Schneider said.

Aureal also claims its chip is significantly cheaper than Creative's. Diamond boards are expected to range no higher than $150, compared with $200 for SoundBlaster Live! And Aureal's Vortex is able to handle applications that use Creative's EAX extensions, while Creative's offerings can't take advantage of A3D, Schneider claimed.

But Creative has its own tricks, stemming from E-Mu's work with musical synthesizers. The 10K1 chip is able to play sound from up to four multiple sources — such as RealAudio streams, telephony signals, or CDs, for example — despite the different sampling rates used by each. The chip's sample rate converters use an eighth-order interpolation developed by E-Mu to shift each signal to a uniform 48-KHz sampling rate, the output standard for AC97.

The goal there is to eliminate pauses that occur when new sound streams interrupt existing ones by stealing processor cycles. "The new standard [AC97] says you can never not be available," said Micah Stroud, Creative's product marketing manager for audio.

Creative is also trumpeting Environmental Audio's ability to enhance the sound in legacy applications, making the EAX extensions applicable to thousands of past game titles. "It turns out it takes only half an hour to turn on Environmental Audio extensions, and the difference is breathtaking. The game makers love it," Massie said.

Aureal, for its part, says A3D 2.0's enhancements will work on A3D 1.0-enhanced games, which are already on the market. Meanwhile, the company expects to see games supporting A3D 2.0 to hit shelves in time for Christmas.