AES Hears EASE and EARS

EASE and EARS Electroacoustic Modeling Software

November 19, 1997

Report by Gary Louie

A joint meeting of the PNW Section of the AES and the Seattle chapter of the Acoustical Society was held November 19, 1997 at Ivar's Salmon House in Seattle. The presentation was by Ron Sauro on the EASE electroacoustic modeling software. Mr. Sauro, of Tacoma, WA, is a consultant who has collaborated with the German developer of EASE, Dr. Wolfgang Ahnert.

Rick Chinn introduced the AES to the ASA members, and passed out a list of AES contacts. ASA program chair Ioana Park introduced Ron Sauro, a leading EASE expert. A video projector displayed the PC screen for the attendees.

Ron explained the gestation of EASE/EARS (Electro Acoustic Simulation for Engineers and Electronically Auralized Room Simulation) in the former East Germany by Dr. Wolfgang Ahnert. It is not a Windows program yet, but has a windowish interface. It started on a Sinclair, went to Amiga, and then to PCs. The Win 95 version is imminent.

Ron described EASE as an acoustic design program, not a systems design program like some other audio programs. It is intended as an acoustic research tool, but systems can be integrated into the modeling. Ease of use is perhaps not as important as getting the right acoustic answer.

Computer models of the acoustic space must be constructed, and model building to the "90 percentile" is needed for 90% accuracy in the acoustic predictions. It can be a chore to draw the model in EASE as in other CAD jobs - several days for an experienced operator, depending on the complexity. XYZ coordinates are used for the modeling. Some tools are better than common CAD programs, although you can import CAD data for use.

To model the acoustics, one assigns acoustic material characteristics to surfaces. Data is available for a wide variety of materials, as well as varied sound sources such as human voices and lathes and all major speakers.

In sound system design, marketing specifications are often slightly at odds with real world performance. EASE gives real specs in situ.

Ron cited an example of a theater in Florida with LCR speakers to be used in mono. The model showed what happens - delays, critical distant, direct/reverberant ratio, RT60, SPLs, RASTI, Alcons, etc. EASE has an Acoustic Probe mode which others do not. This investigates acoustics at any place in the model. Ray tracing showed an analysis of balcony reflection.

EARS is Electronically Auralized Room Simulation, generally referred to as auralization. It takes into account human response factors with a room acoustic model. It can put your ears anywhere in a model room. Ron handed out 6 headphones to demonstrate. An anechoic recording used on an EASE model of the Berlin Philharmonic hall was compared to a real recording with a dummy head. There was some high frequency loss in the simulation, which Ron felt was the PC soundcard, but the simulation was very close.

Software with this capability is obviously a powerful sales tool as well as an engineering tool. Ron played an example of a problematic church sound mixing position, with obvious severe acoustic problems heard in the model. He convinced a church committee to change the position before construction. The architect wasn't convinced - until post construction proved him wrong.

The program is only at the alpha development stage for Windows, but is expected to cost approximately $4500 with EARS when it becomes available.

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