The Sound Environment
Jun 7, 2013 11:20 AM,
By John Storyk, co-principal, Walters-Storyk Design Group
How acoustics and architecture can enhance conference room performance.
In the halcyon days of the Industrial Revolution, boardrooms for mega financial corporations, shipping and railway conglomerates, were basically luxurious, wood paneled meeting rooms. These environments had little concern for technology and possibly even less interest in acoustics. At best, the designers of these rooms did pay some attention to making them reasonably quiet, thus allowing the chairman and other members of the board to hear each other speak. As we know, things have changed dramatically. Today’s modern boardroom is more like mission control. While needing to accommodate advance audio and video playback and broadcast, these rooms still have to remain architecturally exhilarating. At times those dual prerequisites present stark contradictions to what AV and acoustic designers would propose as effective installation guidelines.
Historically, acoustics have been a design afterthought. Acousticians are more often called in to correct problems after construction has been completed than at the optimum moment for their most creative and cost-effective contribution: before the important design initiatives have been set in stone. Small disclaimer, I am an architect and an acoustician, so I am suggesting that readers make every effort to involve acousticians and AV technologists at the beginning of the design process. In my only Management 101 class, I was taught to discuss all issues early and engage all stakeholders immediately. This is particularly important today, when the number and variety of new media connectivity options seems to be spiraling exponentially. How long will it be until we find ourselves dealing not just with 3D visuals and 5.1 audio but also with holographic imagery and fully immersive 20.2 surround sound? Let’s explore only some of the key issues during this design process.
Acoustics: Quietness vs. Internal Room Acoustics
Clients and designers must always remain aware of which of these two acoustic paradigms we are discussing. Keeping environments quiet is typically quite distinct from creating environments that deal with reflection control, decay rate, and ultimately intelligibility of audio. Noise criteria levels need to be agreed to early in the design process. Making a room over quiet (i.e. levels lower than NC25, although possibly a design asset, might be very wasteful financially). Ultimately, any environment can be made to be quiet (i.e. not disturbed by outside noises) if sufficient funds are available to meet the task. But this effort is designed to ameliorate the effects of the audio response within the space. These are extenuating frequency and time domain concerns, and they are concerned with two major issues: geometry and surface treatments.
The dance of these design elements, if performed correctly, will result in appropriate speech intelligibility and the full frequency audio response required in rooms with film and/or video presentation capabilities.
Ergonomics vs. Acoustics
Geometry, when associated with boardroom design, really means ergonomics, the arrangement of people and critical equipment—ultimately the positioning of transducers (microphones, speakers, and ears). It is the composition of these elements along with the surface treatments in the room that will ultimately determine what we hear. It may be strange to read the next sentence, as this is an article on acoustics. But I would never alter an ergonomic design requirement because of a predisposed acoustic standard. Most likely this is because I am an architect at heart, notwithstanding my love of acoustics and music. The positioning of the room’s population along with the situating of critical AV technology required by boardroom occupants (specifically visual imaging such as screens, LCDs, etc.) is our first priority. With the electro-acoustic software design and measurement programs and advanced materialization technology available in our design palette today, we can virtually make almost any environment work with enough intelligence brought to the design process. Towering walls of glass and large ceiling expanse of hard flat plaster can become acoustic absorbers. Low ceiling (low volume) environments can still deliver full frequency (think music) performance for effective playback. Large volume spaces can allow meeting participants to enjoy excellent audio intelligibility.
All parameters in acoustics are frequency dependent. This is one of the first fundamental concepts that any student must learn in trying to deal with acoustics. Most boardrooms need only deal with the speech frequency (we can use 300 to 3000Hz as an approximation for this range). However, many of today’s more complex boardrooms and multi-media presentation rooms have to address frequency ranges outside of these values. If film, video, or music is being presented, a much wider frequency range needs to be addressed and accounted for in the internal room acoustic design. Music is possibly the most difficult area, particularly low frequencies, which comprise most popular cultural presentations (think movies; think 5.1; think urban music; think subs; etc.).
Although there are presentation room environments which will have their acoustic parameters determined solely by full frequency (music) guidelines, for the most part, today’s modern boardrooms need superior intelligibility. The speech intelligibility of an electro-acoustical transmission system can be measured quantitatively. Various metrics are used, such as ALcons, STI, RADTI, or STI-PA. These metrics (although widely used and respected) do not, in certain cases, relate directly to the speech intelligibility as perceived by the listener. This phenomenon is well known in professional practice, but a more accurate metric is (unfortunately) not currently in sight. And too, a “good sounding system,” will not always have a high speech intelligibility index or vice-versa (e.g. the telephone). These, of course, are areas that exemplify the need for skilled professional acousticians.
It might seem that today’s advanced audio-video-control technology may not have much to do with traditional room acoustic analysis. To a certain extent this is true. Decay rates and thus a room’s resulting intelligibility are for the most part independent of an environment’s AV system. However, understanding the basic parameters of the audio systems (delivery and playback) early in the design process could substantially improve the ability to determine the correct acoustic design solution. In general, the more microphones and the more playback speakers in a system, the easier it will be to control undesirable reflections, which will usually result in increased intelligibility. This is not to say that we would always opt for this type of system, but a balance between microphones and playback elements vs. increased room surface treatment should be an early discussion that involves the architect, the acoustician, and the systems designer.
Needless to say, I view all of these disciplines as design elements. There are often large boardroom or media-sharing conference rooms that require individual microphones and playback systems for no acoustic reasons, such as presenter control. When this is a standard requirement, much greater flexibility will be available in room surface treatments control. I cannot emphasize more strongly my original point. A qualified acoustician should be involved at the earliest stages of a project’s design. The time and financial savings of preventing acoustic errors at the design stage can be astronomical.
Walters-Storyk Design Group (WSDG) has designed more than 3,000 media production facilities in the U.S., Europe, the Far East, and Latin America. WSDG principals John Storyk, Beth Walters, and Dirk Noy lecture frequently at universities and industry events, and contribute regularly to industry publications. WSDG is a seven-time winner of the prestigious TEC Award for outstanding achievement in Acoustics/Facility Design, including 2012 for Jungle City. WSDG maintains offices in New York, San Francisco, Miami, Buenos Aires, Belo Horizonte, Basel, Beijing, Barcelona, Mexico City, and Mumbai.