Acoustical Analysis And Voicing
Dear Gary: I am writing to offer a few comments regarding the first installment of the series “The Art & Science of Home Theatre” in Issue 78 Perry Sun suggests that the only agreed-upon method of acoustic calibration is measuring loudspeaker sound pressure levels. Though he may be right in general, I would like to think that we acousticians have more to offer when “Voicing” a home theatre system than that. As an example, my company offers design, modeling, and testing services in addition to room voicing, but in regards to audio calibration, voicing requires a lot more equipment and time to perform than do the video calibrations of today. Typically, modeling precedes voicing. Modeling is software-built estimation of the room’s acoustical characteristics and is an aid in determining design changes to construction materials and methods, room dimensions, loudspeaker/listener locations, acoustic treatments, etc. Voicing itself takes a solid day to perform about two dozen tests, sometimes more, depending on the problems encountered. (This does not include basic system re-wiring, which is needed most of the time.) Voicing is not just measuring and calibrating the electronic equipment, but also the acoustical properties of the room so that they both interact optimally. These tests, however, mean little without experienced ears to offer judgments before and after them. In addition, there are currently no measuring devices for a few very important issues such as depth of image, width, height, fill, and tonal balance. Seasoned ears are the most important tools in the bag. I believe that lack of knowledge is the primary reason that acoustic calibration has been neglected. By that I mean not only knowledge of electronics and acoustics but experience in listening and troubleshooting. Most of today’s [home theatre] dealers are hesitant to talk about acoustics, but they understand that it is the most important component in the system. It has the loudest voice and the last word in the audio chain. Video was scary talked about before the efforts of Joe Kane. And because of his work and the improvements in technology, video set-up requires a fraction of the time and money it did before. Before the LaserDisc A Video Standard existed, I had to borrow equipment from friends at Grass Valley Group to calibrate display devices because I could not afford such equipment. I think in 1989 the first color analyzer I purchased was around $7K. Prior to A Video Standard nobody knew what a good picture was or how to achieve one. It took years to develop a successful video calibration program. The same can be done for audio. True, it will be a little harder to implement because our brains have a harder time comparing audio than they do video. All people have the real world as a visual reference, but few have ever heard unamplified musical instruments or real artillery, etc. Also, video is two-dimensional and has many technical constraints making it easier to set up. As Perry mentions, there is an art to voicing, but to clarify the term, as it should be interpreted in this context, I believe that the artful attributes are derived from science and experience rather than expression and that it has more to do with approach and governing principles and methods than it does opinion. It’s a matter of understanding what’s going on and what can be done to control the conditions so that the original signals are reproduced faithfully. Every room is a new puzzle to solve with different noise control and sound quality issues along with budgetary, physical, structural, and ergonomic constraints. I believe that there is a single “optimum” configuration for a given scenario. The art is making it fit.
Norman Varney, A/V RoomService, Ltd.
normanvarney@avroomservice.com
Managing Editor and Surround Music Editor Perry Sun Comments:
Thank you for taking the time to generously share your insights into the importance of acoustical analysis and setup for home theatre. This is such an important step in helping to achieve the goal of optimized sonic performance. My wish is that there were more respected individuals like yourself who not only recognize the importance of room acoustics and their interaction with audio reproduction equipment, but also have the knowledge, experience, and insight to create the most effective solutions possible.
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