While Dr. Ahnert, S. Feistel and the other EASE developers in ADA were improving and expanding EASE, several European Universities were developing 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 targeted at achieving a high degree of acoustic accuracy coupled with relatively short calculation times. In addition, they included diffusion, which enabled these programs to calculate all known room acoustic measures which ISO 3382, the International Acoustic Standard, recommends for a complete description of acoustic environments.

Perhaps a word of explanation is in order. The classic measures simulated in EASE and EASE JR, such as RT60, D/R Ratio and Critical Distance, are useful indicators of the acoustic performance of the room and its sound system, but do not fully take into account the subjective listening experience. Over the years, acousticians have developed other measures that more fully reflect the listener’s tonal perception of sound. ISO 3382, the International Standard on Room Acoustic Measurements defines these measures.

- Acoustical Measures offered by AURA include: - Earl Decay Time (EDT) - Reverberation Time (T10, T20, T30) - Lateral Fraction (LF) & Lateral Fraction Coefficient (EFC) - Clarity (C80) - Definition (C50) - Sound Strength, - Center Time - Echo Criteria for Speech & Music - STI & Articulation Loss

The AURA module is based on the algorithms Aachen University developed for their Caesar software. Like the 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.

The Caesar algorithms that are the basis of AURA significantly reduce the amount of calculation time required and, when coupled with speedy computers, allow reflection based studies that encompass the entire impulse response length. This usually eliminates the need to add a statistical tail to the impulse response and improves the realism of auralizations.
AURA also includes a Scattering Wizard that allows real-life approximations of scattering coefficients and a Diffuse Rain option that allows the program to accurately include the effects of diffusion in its simulations.

Summary:
With the addition of AURA, EASE has not only caught up with the academic simulation world, it has passed it by offering 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 the EASE family for all conceivable acoustic and electro-acoustic work.