Dr. Ahnert and Dr. Feistel started to develop simulation tools for use in ”electro-acoustic” consultancy jobs, starting with direct sound only. Later they added reflected sound, all in conjunction with commercial loudspeakers. Then Auralization was introduced.

To achieve reasonably natural Auralization, EASE requires the calculation of impulse lengths of 1 to 4 sec duration. For anything but very simple rooms these calculations can take a long time even with a fast computer. Therefore, further calculation of the important late reflections was not considered to be feasible. Instead of a calculated tail (containing the late reflections) a statistically estimated one was added to the calculated first part of the impulse response before auralization procedures were started.

The resultant auralizations are quite realistic, but as explained above, they are saddled with long calculation times and approximations in the late reflections.

While Dr. Ahnert and S. Feistel and the other EASE developer in ADA were working on EASE, several European Universities developed highly specialized room acoustic software from their academic perspective. Odeon (Denmark), CATT (Sweden), Caesar (Germany) and Ramstete (Italy) are examples. These programs were developed by resident scientists and students, refined over many years and were targeted at achieving a high degree of acoustic accuracy coupled with relatively short calculation times.

The AURA module in EASE is based on the physics developed by the Aachen University as incorporated in their Caesar software. Like these other similar programs, Caesar is first and foremost an academic program and therefore somewhat limited for commercial use. For instance, Caesar works only with Omni-directional sources.

In AURA, ADA has augmented Caesar to include commercial loudspeakers, even line-arrays and clusters, in other words, any array of speakers for which ADA can develop their proprietary DLL’s. A connection to the EASE Probe enables post processing, which is also not available in the original Caesar. Most importantly, however, Aura can do a complete STI calculation from the impulse response, which greatly improves on the RASTI approximation via Alcons produced by EASE3.0 or older version of EASE.

AURA also incorporates diffusion (scattering) into its calculations enabling you to study the effects of diffusion on the room’s acoustical performance.

AURA calculates all known room acoustic measures which ISO 3382, the European Acoustic Standard, recommends for a complete description of acoustic environments. This includes:

- Early Decay Time (EDT)
- T10, T29 & T30 Reverberation Time Calculations
- Lateral Fraction (LF)
- Lateral Fraction Coefficient (LFC)
- Clarity (C80)
- Definition (C50)
- Sound Strength
- Center Time
- Echo Criteria for Speech and Music
- Plus Direct SPL, Total SPL, STI and Articulation Loss

A Scattering Wizard is the latest addition to AURA. It allows real-life approximations of scattering coefficients when a materials scattering coefficient is not known.

Summary:
With the addition of Aura, EASE has not only caught up with the academic simulation world, it offers through its connected other features, like commercial speakers, room editing, vision, etc., a unique set of tools, not available in any of the classic academic programs. For the professional user it is now possible to stay within EASE for all conceivable acoustic or electro-acoustic work.