Ease 3.0 for Windows
Mar 1, 1999 12:00 PM, Leslie McLeod
The new version 3.0 of EASE will include all of the functions of its DOS predecessor, but the number of new features far outweigh even this venerable legacy. Although EASE has become the de facto standard in sound system modelling software, the development of a 32 bit version went far beyond porting this familiar tool to Windows. Through the use of OpenGL, a Windows graphics protocol, the program allows detailed rendering that precludes waiting for recalculation when changing views of the 3-D model. The integration of real-time auraliza-tion, from the DSP code experts at Lake DSP in Australia, provides access to this powerful feature from within the program. In fact, you can now listen to direct sound from loudspeaker sources just seconds after you select a listening position.
Conceived by Dr. Wolfgang Ahnert of ADA (Acoustic Design Ahnert), Berlin, and programmed and compiled using Visual Basic by Rainer and Stefan Feistel, the Enhanced Acoustic Simulator for Engineers (EASE) has risen to the forefront of computer modelling tools for acoustical and sound system design. This has happened over the past decade by garnering support from the widest spectrum of loudspeaker manufacturers and by yielding measurable correlation between model and finished project. With more than 2,000 users around the world, EASE has become familiar to architects, engineers and building owners that need to know sonic characteristics before the building is finished. The new 32 bit version will extend the level of detail possible within the model and reduce the processing time required to analyze or listen to the results.
Although the functions of the previous versions of EASE (modelling) and EARS (auralization) have been integrated into this new version, the result forms a group of 12 software modules. The program loads a base application that includes all of the Project Data. From this module, other applications are called as functions require, and then the data generated in these external modules are communicated back to the Project Data module using OLE (Object Linking and Embedding) automation functions of the Windows OS. This data is also distributed to other modules automatically or by selecting Upload/Download commands within each module. The modules can be run as stand-alone applications should a narrow investigation be required.
The database for acoustical materials and loudspeakers has been extended to offer far greater detail. All data is in 1/3-octave resolution and loudspeaker polar data can be imported with 5 degrees accuracy. Data that does not reach this resolution (such as importing projects from the previous version) will be interpolated automatically. The program will convert data from previous EASE 2.1 projects, including wall materials and loudspeaker data, and it will now import CADP2 data. The result is a program that allows many current users of either software application to import existing projects and extend investigations using the new facilities of this powerful program. Complete EASE projects can be packaged for filing with the project or sharing with other users. This feature generates a single compressed file with all of the related project data.
The mapping functions of EASE play an important role in the analysis of sound system and room acoustical behaviour. Through the use of OpenGL source code, EASE is able to control graphical elements and perform screen redraws quickly. This results in fluid rotation and fly-through animation of the model. Providing more than simply cool graphics, the program allows the user to move readily through the model to visualize the relationship between surfaces in the model, loudspeakers in a cluster or sound levels on a painted map. The use of OpenGL extends to all of the 2-D and 3-D mapping and rendering functions so that users never have to recalculate or redraw a coverage plot while examining minute details within any part of the model.
The program is made up of a family of applications that interact using OLE. These modules include EARS, the auralization component of the program, which was a separate, optional program in the previous version and is now fully integrated into EASE but remains an extra-cost option, for listening to the model, and EYES, the mapping and rendering component, which allows all of the acoustical and loudspeaker data to be visualized. This visualization extends beyond the basic mapping of previous versions, to include new information, such as the colour of surfaces based on their alpha value (absorption coefficient) at any selectable 1/3-octave band. This new view will allow the user to see the degree of acoustical absorption each surface provides in a selected 1/3-octave band with darker colors indicating greater absorption.
The visualization extends to new capabilities in showing loudspeaker components. The walls of horns and cabinets of loudspeaker systems can now be mapped in the same colourful way as faces and areas. The array now takes a solid-looking form within the model that is true to scale. The 3-D representation does not, however, interfere with the acoustical properties of the loudspeaker devices, so these faces on the loudspeaker components (Case Faces) do not produce inappropriate shadows when calculating coverage maps.
Loudspeaker data has been increased in resolution to 1/3-octave and 5 degrees increments for polar data. Acoustic origins are now defined independently for each band of the loudspeaker to improve the way the model calculates interference within a loudspeaker and among components in an array of loudspeakers. This can extend to the acoustic origin being defined as existing in space between two components of the loudspeaker at the crossover frequency. There is a mechanical reference point defined for the loudspeaker, which is independent of the acoustical properties, for use as a rigging reference or locating point when creating documentation for positioning the unit onsite. The loudspeaker information includes user-defined crossover and EQ in addition to the overall level, signal delay and orientation settings.
The loudspeaker data is now in separate files for each loudspeaker device rather than the combined catalogue files of the previous version. A project will now include pointers to the database of loudspeakers rather than create a new catalogue of data for each project. Data for loudspeakers supplied by manufacturers, however, does not currently include all of the parameters available for modelling in EASE 3.0. It may take some time for this new level of information to become available from all loudspeaker manufacturers.
Loudspeakers can now be combined into arrays, which can then be stored as pre-defined components for later use. The user can develop a complex array that may include driver alignment delay, frequency shading or even beam steering and save the result as part of the loudspeaker component library. A new Balloon-Show feature also allows the interference patterns of an array to be examined in detail. This includes 3-D mapping of the far-field response from the combined devices that may be viewed from any angle, including anywhere inside the balloon. The calculation of interference is selectable between complex power summation (interference), the Ureda method and simple power summation. Mapping the level, speech intelligibility and arrival time of sound from loudspeakers is no longer restricted to audience areas. Now, any face in the model can be painted by these mapping functions. Although only far-field calculations are valid for detailed analysis, the intensity of sound on nearby surfaces can warn the user of potential problems associated with nearby beams or overhangs.
Acoustical materials can include 1/3-octave data (available from some of the major suppliers by request but rarely published in this resolution), but importing Version 2.1 EASE data includes an automatic interpolation of octave-band data to this new format. The wall material data includes a field for 1/3-octave diffusion-coefficient data; however, this information is currently unavailable and awaits support from the industry.
Viewing the model has been enhanced to include the Omniview, familiar to CADP2 users, where a 3-D, side, front and top view are all active on the screen. This enhances the speed of entering and editing the model when it might be difficult to maintain a reference from just one view. To maintain a sense of scale, 2-D and 3-D grids are available to improve the accuracy of freehand drawing. The user can elect to snap to the grid and ensure that objects are placed exactly. The grid spacing can be resized to suit different aspects of the drawing process.
Using the conventions of 32 bit Windows software, the new version of EASE puts context-sensitive commands just a right click of the mouse away. In the event an error is made in creating or editing the model, the levels of Undo are unlimited, although they can be reduced if resources are limited on the user's computer.
New tools have been added to expedite the process of building a 3-D model, including more powerful duplication modes, such as linear and curved arrays familiar to AutoCAD users. In addition, a Sequence command provides a method for entering a series of objects. such as faces or loudspeakers, that are not evenly spaced. These commands can create a complex series of balconies, stepped ceiling planes or doorways in just a few steps, and 3-D objects can now be trimmed (Freeform Cut) to truncate complex surfaces as they meet at a single plane. Objects can be grouped to allow movement, duplication or removal in fewer operations. Grouping can allow loudspeakers to be reoriented in a locked array.
Extrusion offers an interactive graphic method of creating 3-D objects, for example, to generate walls and ceilings directly from the floor plane. With up to 64 vertices defining a single face in the model, complex shapes can then be extruded in a single pass. Duplicate allows selected objects to be copied and pasted in a single pass. Selecting vertices within a model has been enhanced to allow visually overlapping vertices (due to the current view perspective) to automatically bring up a dialogue that offers selection from the list of vertices in the immediate area. Solving problems with faces that do not form a plane has been improved with a Flatten command available on the right mouse (contextual) menu, and the Face Properties dialogue box includes a spinning view to improve the visibility of non-flat errors in the current face. A table for the current object can be accessed from the right mouse button to allow exact numeric entry of details in the location or other properties of the object.
A special function called Seat Grid allows the user to fill an area with seats. This can instantly populate a seating area with hundreds of listener seats. Sound sources can then be examined for their interaction with sound reflecting surfaces that impact these seats, a powerful new tool for reviewing the shape, size and location of reflecting panels in venues.
The auralization features offer the greatest increase in power in this new version. The familiar EASE Probe now includes a Walker that can generate instant auralizations of direct sound at the current location. To listen to the acoustical conditions of the model, ray-tracing speed has been greatly enhanced by full access to 32 bit math and the latest Pentium processing. Now, complex models can have a maximum four seconds of impacts (sound rays from the source that reach the listening position) rendered and made audible right from within the program. Additional late reverberation can be added to the reflectogram after the initial impulse response of the room is calculated. The resulting combined impulse response is then convolved for auralization within the EARS module of the program.
The EARS module includes a licensed algorithm from LAKE DSP of Australia that generates the auralization in real time from streaming audio. With typical latencies of less than 300 ms, this software engine allows instant comparison of various listening locations or conditions with complete binaural localization. A cross-correlation algorithm developed by Dr. Floyd Toole of Harmon International, will allow these binaural HRTF (Head-Related Transfer Function) files to be heard with the same 360 degrees localization over stereo loudspeakers. The LAKE processing functions also support the TIM file format, which will allow measured transfer-functions to be directly compared to those derived within the EASE model. Real-time streaming of audio through the LAKE process within EASE will require a PC with a full-duplex sound card and provide the functionality that has previously required more than $10,000 in DSP hardware. Half-duplex sound cards will limit the user to playing back WAV files through the auralization filter.
The Walker function can also be used to produce animated AVI files that allow the user to display a dynamic moving view of the rendered model to the client. The Walker View is a form of the probe function that allows 3-D navigation within a fully rendered view of the model. The Walker is moved to areas of interest to the user, and buttons are available to probe that location for data in the form of reflectograms, 3-D Waterfall displays and directional hedgehog displays along with comb filters and other aspects of the frequency response. A Walking button will set this view in motion, automatically moving through the model.
Bringing EASE to the Windows OS has been a long-awaited event for users of this comprehensive modelling program. The new features not only address the requests from users, but also raise the standards of computer modelling for sound system and room acoustics. Be aware, however, that the variations in Windows 95 implementations will require the attention of the user during installation to ensure that support for OpenGL is available. The removal of memory restrictions in Windows 9x and NT allows users to create more detailed models and analyze the results, both visually and audibly in ways that should push forward the craft of sound-system design. The initial release of EASE version 3.0 for Windows is scheduled to coincide with the 1999 NSCA convention. Renkus Heinz is the world-wide distributor for EASE, while Telex/EVI distributes the program exclusively through its dealer network.
Now, when the sound system designer tells the architect that a problem will sound bad, it is far more convenient to make this problem audible. Tools, such as EASE 3.0, may actually make room acoustics and sound system design more tangible to the other members of the building design team. The result should be better room acoustics and sound systems as the modelling process allows more detailed study of conditions and better tools to communicate the criteria to the decision makers involved the process of creating buildings.
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