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EASE 4.0

IN THE TWO YEARS SINCE THE INTRODUCTION OF EASE Version 3.0, the software has experienced many upgrades, but Version 4.0 represents a major change to

EASE 4.0

Sep 1, 2001 12:00 PM,
Ron Sauro & Theresa Meyers

IN THE TWO YEARS SINCE THE INTRODUCTION OF EASE Version 3.0, the software has experienced many upgrades, but Version 4.0 represents a major change to a more intuitive and easier-to-use format with more realistic and accurate calculations and presentations. Just how different is it? The jump it made from 3.0 to 4.0 is easily as big as the jump it made from 2.0 to 3.0, and if you don’t remember that, read on….

Originated by Dr. Wolfgang Ahnert of ADA (Acoustical Design Ahnert), Berlin, the Enhanced Acoustic Simulator for Engineers developed over several versions into the de facto standard for sound-system modeling software. The program helps architects, engineers, consultants and contractors discover sonic characteristics before a building is finished. Version 4.0 contains enhanced capabilities and new additions that remove previous limits for many design elements. These additions also extend the visual detail within models and significantly cut the time required to produce complex models.

WHAT’S NEW IN 4.0

The most significant additions to the program are phase data for loudspeakers or systems; Caesar, a complex acoustical mapping module; and EASEVision, an architectural rendering module. EASEVision includes a texture editor, a light-source editor and the new EASE function that allows loading of EASE mapping files (both 3-D bitmaps and 2-D files). EASE now saves the calculation instead of just the picture.

Souped-up Speaker and Filter Data

EASE 4.0 offers upgraded speaker data designed to make calculations more accurate than before. All new phase data and phase balloons create views of what speakers can do not only in magnitude and frequency but also in phase, allowing the simulation of new complex line arrays that use phase changes to control the directivity of the line array.

Complex filters for loudspeakers extend the function found in version 3.0 that allowed users to input a single crossover point and set the level of each speaker. The new filters remove these restrictions, allowing the use of phase/delay data in the calculation of the total response of the speaker and/or cluster. This produces not only more realistic simulations, but also makes it possible for users to simulate some of the newer types of speakers, such as DSP process or control speakers, which require phase data for calculations.

In previous versions of the program, information on speakers was set, and phase differences were not taken into account. In EASE 4.0, Custom Speaker Dynamic Link Libraries allow designers to use proprietary information without divulging their techniques through a series of commands that are hidden via a black box with an input and output function. Users can now simulate line arrays without the release of proprietary control information to the public, allowing them to change the parameters of those speakers for aim, distance and frequency, just as in real life. The information afforded by the Custom Speaker DLLs is also incorporated into the balloon calculations so that the balloon of the line array can be simulated. This new set of data makes it possible to compute the direct sound pressure level field for any speaker model or speaker DLL.

If data is imported from EASE 3.0, EASE 4.0 will allow calculation of the minimum phase behavior based on the frequency response of the speaker, but it can replace this calculation once phase measurements are available from the manufacturer.

Hail Caesar

EASE 4.0 represents the launch of Caesar, the new modeling module. While it is an extra-cost item, it is well worth it. Developed by the scientists at The University of Aachen, Germany, and ADA, the module allows calculations of acoustic parameters with exceptional accuracy. Calculations available through the program include direct SPL; total SPL; early decay time (EDT); T-10, T-20 and T-30 (decay times calculated using 10, 20 or 30dB ranges); definition; center time; LF; LFC; sound strength; echo speech; and echo music. Did you get all of that?

Until now, EASE has functioned as a sound-system design program that allowed users to create buildings in virtual reality and simulate the parameters for such calculations as direct SPL, total SPL, alcons, RaSTI, level and clarity. These parameters, although full of information, don’t completely describe the acoustic performance of a room. For that, designers need to look at acoustic parameters such as EDT, echo, T-10, T-20 and T-30, and others. The Caesar module converts EASE into an acoustic design tool as well as a sound-system design tool, making it possible for EASE to compete directly with such programs as CATT-Acoustics and Odeon. This represents a major change in the direction of the program.

The module also has the ability to calculate a Caesar RSP/BIR (binaural impulse response) file, which is the binaural impulse response of the room using a new hybrid algorithm (see the Caesar Sidebar). Ray tracing in Caesar has also been given a boost with the addition of a new algorithm. The particle-loss algorithm increases calculation speed by nearly 20 times. This option is perfect for initial calculations, but EASE reminds you that energy loss is the preferred method for final calculation accuracy.

In conjunction with Caesar, diffusion can be used for calculations that are made with ray tracing. In Version 3.0, the co-efficients simply weren’t available, and it didn’t matter whether a surface was rough or smooth — the reflection angles were calculated using the isotropic method. The fact is, a certain amount of diffusion happens in real life. So the new version takes those realities into account using Lambert’s Law as a basis for the diffusion coefficients, but these diffusion calculations are only used in the Caesar module.

The Caesar module offers an easy and expedient method for analyzing a room accurately for pure acoustics with sources such as the human voice. The ability to calculate directional sources and receivers in addition to omnidirectional sources and receivers is opening up a new world for acoustical designers in EASE 4.0.

Ray-Tracing Module

In version 3.0, the program had a maximum of 19 orders of reflection. Version 4.0 removes those limits, allowing users to create real ETC tails.

Lights, Texture and EASEVision

Three additions found in EASE 4.0 — the new EASEVision rendering engine, the texture editor and the light-source editor — enable users to enhance final designs through added textures, lighting, colors, shadows and shading, making the models more realistic for the customer and, therefore, a better sales tool.

EASEVision is an architectural rendering engine that contributes a whole new dimension to designs, literally. Shadows and shading take on new meaning in EASE 4.0, allowing sharp detailing of both with very fine resolution and color rendering. This makes the computer model much easier for the client to visualize. While not photographic quality yet, it’s getting close.

The texture editor and light-source editor offer a significant step in improving the realism of models. The light-source editor gives users the capability of inserting realistic lighting details into their models. With the click of a mouse, luminaire locations, different directional characteristics, colors and intensities can all be modified and viewed within the model.

Added to this is the texture editor, which enables users to import bitmap textures, then edit, change and insert those textures into the model for life-like images of brick walls, carpeting or even the view out of a window. These textures are not only for diffuse lighting (pictures on the wall) but also simulate reflective light (mirrors), transmitted light (glass), shininess (metallic or smooth spots), self-illumination (monitors) and bump mapping (3-D structured surfaces).

EASEMapping Viewer

In another leap of time-saving programming, EASE 4.0 incorporates EASEMapping viewer, enabling users to load EASEMapping files. Until now, every time a user calculated a map it either had to be printed out or thrown out. If you wanted to see it again, it had to be recalculated. There was no option to save it. EASE 4.0 changes that, allowing calculations to be saved as an EASEMAP file. The new EASEMapping viewer can reload and display a saved selected map calculation from the EASEMAP file thus allowing it to be re-rendered at any time. These selected map files can then be compared in multiple windows, which users can manipulate at will. This means that all calculations for a room can be accomplished at one time, saved, and then displayed without the time-consuming recalculations.

A New Interface

Along with these new modules, EASE 4.0 also sports a different and improved look and feel. Icons and redesigned menus bolster ease of use, and the program now allows for instantaneous jumps from module to module. Creating new projects, mapping functions and ray tracing are now easy-to-use “wizards”. The programming in 4.0 is task-oriented rather than data-oriented (as it was in the earlier versions), making the program readily navigable for average and experienced users alike.

New icons take users directly to functions, such as calculating direct SPL, without having to open a new window or select the function with a mouse. Users will also appreciate the new desktop that allows flexibility to create individual user-preference shortcuts and place them within easy reach. Mapping wizards save time by placing all setups of calculations in a single spot.

Object Function Means More Power

The new Object function offers the greatest increase in power in the new version of EASE. This function, equivalent to creating blocks in AutoCAD, allows users to select any items in the drawing including vertices, faces, edges, seats, lights or speakers; group them together and then save them into a separate file as an object. This object can then be imported into the model, duplicated, rotated or moved in any of three axes to allow rapid insertion of complicated details. Objects can also be edited and modified. This function represents an incredible time savings to the designer and should slash 25 to 50 percent off the input process

EARS Enhanced

Other enhancements to EASE 4.0 include changes in EARS, the auralization module. This module now has the capability to convolve different sources and different program material and combine them so they are related in level to each other. The EARS module within EASE 3.0 only allowed one source convolution to be mixed with another convolution without automatic relative leveling, making realistic assessment of areas such as classrooms (with the competing sounds of a teacher’s voice and children at play) impossible. By removing these limits, EASE 4.0 takes a step toward more accurate calculations and representations for designers.

A Kemar dummy head has been added to the list of possible receivers, which allows selection of binaural calculation parameters. While it wasn’t possible to see Head-Related Transfer Functions graphically represented in 3.0, EASE 4.0 does allow the user to show both the directionality and magnitude of HRTF balloons. These can be rendered in a solid form and vivid colors to depict energy levels similar to those shown by a speaker balloon.

Probe Improvements

Also enhanced in EASE 4.0 is the Probe, which can now compute Modulated Transfer Function and Rapid Speech Transmission Index. In version 3.0, the RaSTI calculation was a conversion directly from Alcons. EASE 4.0 offers actual calculations at all the pertinent frequencies. Users can now also calculate the entire tail of a room impulse or an Energy Time Curve to give a more realistic impression of the room. Local decay computation is also possible, using essentially the same calculation as Seat Local RT (Reverb Time) in EASE 2.1. This provides more accurate EARS and ETC simulations.

Introducing Maps with Reflected Energy

Users will also be pleased with the changes in the standard mapping/render-mapping functions in EASE 4.0. Users now have the ability to map using reflections as well as the calculations based on direct sound and statistical reverberation. Early reflections, calculated to a time determined by the user, can be included in standard mapping and render-mapping calculations, making for a more accurate representation of what is actually occurring in the space. Local ray tracing allows users to generate a ray trace from any seat, resulting in the calculation of local decay time as well as calculations of early reflections.

Other mapping improvements are also incorporated into EASE 4.0. In EASE 3.0 all mapping was done by type and single frequency. EASE 4.0 eliminates these restrictions. Users can now select one of three ways to complete mapping. Single creates a selected map at one frequency; All Frequencies creates a single map at all frequencies; and All Maps builds just that — all maps at all frequencies.

Better Project Data

In addition to the new Object function and light-source and texture editors mentioned earlier, project data in EASE 4.0 has been improved with changes to the Extrusion function. Until now, Extrusion functions have been limited to faces. Now vertices and edges can also be extruded, giving designers additional flexibility and creative capabilities while dramatically saving them time. The limit on the number of vertices has also been lifted in EASE 4.0 (the limit was 10 in version 2.0, and 64 in 3.0). Users can also activate or deactivate multiple items.

Of special note is the new ability to import out of CAD 2D and have 2-D vector files become useable 3-D files in EASE 4.0. This represents a huge savings in time because, on the typical project, as much as 60% to 70% of the time is spent just rebuilding the model from faces and vertices to match architectural drawings.

Other Enhanced Capabilities

Materials databases now can have longer names, more complete descriptions of all materials and more information on the data testing procedures. Data on file includes the phone numbers and addresses of manufacturers where available. Other enhancements found in version 4.0 include the support for long file names of up to 255 characters, long item names up to 255 characters, and a higher maximum number of items, now exceeding 32,676.

Printing pages with specific details is easier, too. A new printing engine in version 4.0, EASEPaD (EASE Page Designer) replaces Arrange, with functions that are like CorelDraw, so users can add words, highlights, labels, pointers and model images into typewritten pages.

Because of the significant upgrade this version of EASE represents, it may be time to upgrade your operating system as well. Windows 98 is recommended as the minimum operating system; the program will run also on Win ME, NT 4.0 and Windows 2000, as well as Windows XP.

The initial release of EASE 4.0 is scheduled to coincide with the 2001 AES convention. Renkus Heinz is the worldwide distributor for EASE, and Telex/EVI and JBL also offer the program through their dealer networks.

Overall, EASE 4.0 represents a significant jump in the program’s evolution and the productivity it offers. Contractors can get information in less time than required for version 3.0, and the information will be more accurate.

EASE 4.0 marks the program’s evolution into the realm of pure acoustic modeling. Having been used only for modelling sound systems, it’s now entering into the world of architecture and lighting design. The result should be more acoustically accurate designs, a decrease in the time necessary to produce those designs, better communication of concepts to clients and decision makers, and an increase in overall profitability for the designer.

Ron Sauro is the owner of Northwest Audio and Acoustics. Teresa Meyers is a freelance writer.

Operating system: Windows 98 recommended

Memory: 128 MB minimum

Hard Disk: 300MB available disk space required (full install).

Processor: 166MHz Pentium or higher

Manufacturer: Acoustical Design Ahnert; [email protected]

Caesar and EASE
Friends, Romans, Contractors: Lend Me Your EASE!

EASE 4.0 adds Caesar, an acoustical simulation engine, to its existing electro-acoustical simulation capabilities. This module combines a 3D-CAD interface and loudspeaker and materials database with a hybrid image source/ray-tracing algorithm. A new simulation capability, diffuse scattering, allows the calculation of standard room acoustical parameters according to ISO3382, and also the creation of binaural impulse responses for auralization.

Historically, electro-acoustical simulation programs have had several flaws, which Caesar improves on.

If the user was interested in more than just the direct sound coverage, electro-acoustical simulation programs used the mirror image method to account for the room’s influence on transfer of sound. But, for reasonable calculation times, the classic mirror image algorithm can calculate only three to five reflections in medium-size rooms; calculation times for higher orders of reflections exceed other (hybrid) room acoustical algorithms. If a full impulse response was required, a random tail, calculated from the reverberation time using diffuse field theory, was often appended.

This has some strong disadvantages. The mirror image method only allows geometrical reflections. Surface scattering, which is of high importance in most cases, cannot be taken into account — it is assumed that the surfaces are scattering perfectly. Many rooms where electro-acoustical installations are implemented (long or low-ceiling flat rooms, for example) do not have diffuse fields, which can lead to large calculation errors.

Also, Caesar’s loudspeaker database of source characteristics allows it to avoid traditional room acoustical simulation software’s assumption of simple loudspeakers with magnitude-only directivity data. The assumption that sound sources would all possess ideally spherical directivities is the result of other programs’ lack of a source characteristics database like Caesar’s.

The New Ruler

EASE combined with Caesar requires no assumptions like a diffuse field present in the room. Only the room/surface condition and the calculation time (and the quality of the input data) are relevant to the accuracy of the simulations. Depending on the goal of the simulation, different algorithms are used. For calculation of monaural room acoustical parameters, the ray tracing algorithm is applied. Binaural impulse responses for auralization are calculated using a combination of the hybrid mirror image method and a modified ray tracing algorithm.

Room Acoustical Parameters

Caesar/EASE supports the following parameters: early decay time (EDT), reverberation time (T10, T20, T30), lateral fraction (LF), lateral fraction coefficient (LFC), clarity (C80), definition (D50), sound strength (G), center time, direct and total SPL, and echo criteria.

These are calculated from energy-time curves (ETC) measured or simulated using an omnidirectional microphone, and, where needed, a figure-eight microphone (per ISO3382). Because the ETC’s temporal fine structure is not important, a ray-tracing method, which collects the energy for each receiver in an ETC at time intervals of one millisecond and calculates these values in twenty-one ⅓-octave bands from 100 Hz to 10kHz, is used.

Two echo criteria, for music and speech, are also calculated from this data. Usually all of these parameters are evaluated for a large number of receiver positions to allow a color-mapped display of the results.

ISO3382 requires the use of omnidirectional loudspeakers and microphones to measure most of the parameters. For lateral fractions, a figure-eight microphone is required. ISO3382 also states that “the null of the figure-eight microphone shall either point to an average center-stage position or exactly towards individual source positions.” In the case of a multisource setup, the user has to choose the main or primary source. All receivers will then orient automatically towards this source.

To allow faster calculation, the absorption at the walls can be calculated with a particle-loss method instead of the energy-reduction approach. Rather than reducing the energy of the sound particle, the number of sound particles is reduced over time. For an infinite number of particles, the results of both methods are identical. For a finite number, however, particle loss is faster but less accurate.

Auralization

For auralization, higher demands are placed on the calculation of the ETC. The early reflections need to be calculated with exact temporal structure, while the scattered reflections are also necessary in the early impulse response to make it sound natural. Therefore, a combination of the hybrid mirror image method and ray tracing is implemented.

The mirror-image method is used to calculate the geometrical reflections for the early part because it supplies a time resolution only limited by the accuracy of the floating point accuracy of the CPU. The ray-tracing method is used to calculate the early scattered reflections and the complete late part. The late part of the impulse response is characterized by its statistical properties, not by the fine structure, where the low time resolution of the ray-tracing method is not a limitation. The fine structure of the pressure-impulse response is added statistically in the post processing. In this case, energy reduction must be used, or the errors in the late part of the ETC will lead to an impulse response, which sounds unnatural because the ETC will have intervals with zero energy.

A criterion for the transition between algorithms is required. For Caesar implementation, the reflection order is preferred over the time-limit method. The main reason for this choice is that strong late reflections, typical for flutter echoes, for example, will not be detected if time is used as the limit.

It’s arguably the best simulation going.

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