Environmental audio extensions

Environmental Audio Extensions

Creative EAX logo
Original author(s)	Creative Technology
Developer(s)	Creative Technology
Last release	5.0
Development status	deprecated
License	proprietary

The Environmental Audio Extensions (or EAX) are a number of digital signal processing presets for audio, present in Creative Technology's later Sound Blaster sound cards and the Creative NOMAD/Creative ZEN product lines. EAX displaced the alternative A3D (Aureal 3-Dimensional) in 2001. As of 2010, EAX is rarely used, with modern games utilizing the CPU to process 3D audio rather than relying on dedicated hardware.

EAX is a library of extensions to Microsoft's DirectSound3D, itself an extension to DirectSound introduced with DirectX 3 in 1996 with the intention to standardize 3D audio for Microsoft Windows, adding environmental audio presets to DS3D's audio positioning. Ergo, the aim of EAX has nothing to do with 3D audio positioning, this is usually done by a sound library like DirectSound3D or OpenAL. Rather, EAX can be seen as a library of sound effects written and compiled to be executed on a DSP instead of the CPU, often called "hardware-accelerated".

The aim of EAX is to create more ambiance within video games by more accurately simulating a real-world audio environment. Up to EAX 2.0, the technology was based around the effects engine aboard the E-mu 10K1 on Creative Technology's and the Maestro2 on ESS1968 chipsets driven Sound Cards. The hardware accelerated effects engine is an E-mu FX8010 DSP integrated into the Creative Technology's audio chip and was historically used to enhance MIDI output by adding effects (such as reverb and chorus) to the sampled instruments on 'wavetable' sample-based synthesis cards (Note: it is often confused with the "wavetable synthesis" developed by Wolfgang Palm of PPG and Michael Mcnabb in the late-1970s, however not related). A similar effects DSP was also present on Creative's cards back to the AWE 32. However, the EMU10K1's DSP was faster and more flexible and was able to produce not only MIDI output but also other outputs, including the digital sound section. A person who has been exposed to MIDI effects processors will quickly recognize the parameters that EAX controls, and the names of many of the presets