Chapter 11: AURA

A U R A

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EASE 4.3 User’s Guide & Tutorial

Chapter 11: AURA

The AURA, Analysis Utility for Room Acoustics, module is an extremely powerful acoustical analysis tool.

Based on the CAESAR algorithms developed by Aachen University (RWTH), AURA allows the calculation of all key room acoustical parameters defined in ISO3382, the International Standard on Room Acoustic Measurements. These include

Early Decay Time (EDT) Reverberation Time (T10, T20, T30) Lateral Fraction (LF)

Lateral Fraction Coefficient (LFC) Clarity (C80)

Definition, C50

Sound Strength Center Time Direct SPL Total SPL

Echo Criteria for Speech and Music STI and Articulation Loss (AlCons.)

AURA is a tool for producing more accurate and realistic acoustical simulations. AURA initially creates an Echogram (Reflectogram) and then extracts from the Echogram most of the measures simulated in Standard Mapping, plus a number of standardized acoustical measures that give the user a more detailed picture of the room's acoustics and performance.

Whenever an adequate number of reflections are simulated, an AURA simulation is more accurate than one created solely from statistical mapping, which estimates the diffuse field from reverberation time values calculated using generalized formulas. Statistical mapping, however, requires less time and computer horsepower to produce its simulations.

We will use a new model for our AURA exercises. You will find the room in the Examples folder under EASE40 Data. It's identified as AURA1.

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AURA provides two simulation methods, AURA Mapping and AURA Response:

AURA Mapping will map the acoustical measures (according to ISO standard 3382) on Audience Areas or at individual Listener Seats by developing an Echogram. AURA Mapping results are adequate for mapping purposes but not for Auralization.

AURA Response, on the other hand, calculates a Reflectogram, from which a Binaural Impulse Response can be extracted and used for Auralization.

Before we start exploring Aura’s capabilities, let’s take a look at the room using Area Mapping to get a feel for its performance.

Select Area Mapping from the Calculations pull down menu. The first thing you will notice is that the Main floor Audience Area is obscuring the Balcony Audience Area. The designer forgot to move one of the audience areas so this wouldn't happen. No problem, return to the Edit Project module and select Area Layout from the Edit pull down menu. Then select Move from the Edit pull down menu and grab the Main Floor Audience Area and move it out of the way.

Now click on the Direct SPL icon. Select all five loudspeakers and both Audience Areas in the Settings setup screen Also check All Mappings,then click on Next. When the Items and Noise screens open, accept the default settings by pressing on Next. In the Calculation window make sure that Map with Shadows is turned On and then press OK.

Return to the Area Mapping screen and rerun the Direct SPL simulation. As you can see from the 1000 Hz to 4000 Hz plot shown below the loudspeaker system is producing fairly smooth, high level direct sound coverage except in the corners of the audience areas.

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Next, run an STI simulation. As you can see the intelligibility looks pretty good.

This would also be a good time to look at the room’s RT60. Return to the Main menu and from the View pull down menu select Room Info/Draw RT.

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