Introduction
Ask most frequent presenters what is the ideal venue for public speaking and they’ll likely tell you, “Whichever one is full.” Especially for certain types of presentations like sales or investment pitches, a larger audience can translate directly to a more successful venture. But ask a sound designer, an architect, or an engineer and you’re sure to get a very different answer — one that’s less concerned with how many butts are in the seats and more focused on how those people are experiencing the presentation, play, speech, or other performance. Since nearly all stage performances outside of improv comedy are one-way in nature, the primary interaction between audience and performer is auditory. The study of the dynamics of that interaction is known as acoustics.
In short, acoustics is “the science concerned with the production, control, transmission, reception, and effects of sound.” For presenters, this means when you talk, your audience hears what you are saying. Ideally, your audience’s ears would be close (but not too close!) to your mouth or amplifying equipment, i.e. speakers. But in most real-world situations, especially large or multiple use auditoriums, that’s just not feasible. So how do engineers and other technicians make sure that the sound reaches all members of the audience as optimally as possible? With their knowledge of acoustics!
As Brigham Young University’s Department of Mechanical Engineering notes on its Acoustics Research portal, a common misunderstanding of acoustics restricts its scope to musical, vocal, and architectural pursuits (which is what we are chiefly concerned with, as presenters.) However, in an effort to present a comprehensive picture, we should note that the applications of acoustics are actually quite diverse. Navigational SONAR (SOund Navigation and Ranging), ultrasound imaging, and seismology all fall under the umbrella of acoustics, and those are actually just some of the more common examples.
The Acoustics of Auditoriums
There are a variety of methods available to engineers and architects to achieve the optimal acoustical properties in a given space, not the least of which is the liberal application of sound-dampening and acoustically reflective materials. Depending on the relative location of a given surface, a sound designer may want the sound coming from the stage to bounce off and either travel to the audience or to an area where it will not be heard, if the reverb is judged to be harmful to the overall sound mix.
On the other hand, much of the acoustic material typically visible to the audience is devoted to a different task altogether: absorbing or dampening the sound waves that emanate from stage in front of them. Most of the time, the idea behind the application of these materials is to keep the sounds from echoing off of the walls of an enclosed space, a phenomenon which, if left unchecked, would likely produce a very aurally confusing experience for the audience. The National Institute of Building Sciences, in their Whole Building Design Guide, provides some general rules for acoustic material application:
“Strategies to achieve the recommended NC [Noise Criteria] and STC [Sound Transmission Class] ranges include, for example: Type II vinyl wall covering and fabric covered acoustical wall panels for the interior wall finish in the auditorium; Type II vinyl wall covering for the stage area; Type II vinyl wall coverings for 1/3 of the front of the orchestra (audience) sidewalls and fabric covered acoustical panels for 2/3 of the back of the orchestra (audience) sidewalls; fabric covered acoustical panels for rear walls; and a plaster and plywood combination—because of their reverberation characteristics—for the ceiling.”
The use of fabric panels for their acoustic properties is not a new idea by any means — they’ve been deployed in recording studios for decades. Here’s an example of some portable panels in use during the recording of violinist Diana Yukawa’s album at the infamous Abbey Road Studios in London, England.
It may be difficult to imagine that the same principles that make for a good recording studio are also applicable to presentations and public speaking. But according to William Elliott, an architectural acoustics expert, exhibiting in an auditorium that is multiple use in nature actually isn’t a death knell for good speaking acoustics.
“Although the multi-purpose nature of the auditorium may appear to place many constraints on the acoustical environment, there is a set of design principles that, if followed, will produce interior acoustics that always complement the sound source, whatever (or wherever) it may be. An auditorium with proper acoustics encourages the audience to contemplate the acoustical content (be it oratorical, dramatic, or musical) of the sound source. An auditorium with poor acoustics is immediately apparent and detracts from the presentation.”
In his post for Christian School Products, Elliott goes on to explain that there are four basic elements to the acoustic success of a school auditorium. This type of space is the ideal test case for presenters since, like many event spaces on the road, the usage is diverse and unpredictable. Presenters may often arrive to give a talk or pitch and find that the room is not used exclusively for presentations, or is poorly equipped to handle them. A school auditorium needs to be available for musical performances, dramatic plays, announcements, and other events, so a careful engineer will have prepared the space with this diversity in mind.
1. Background noise is generally identified by the Noise Criteria metric introduced above, and is a measure of all of the sounds generated by the environment of an arena. The lower this number, the better. The Sound Transmission Class is essentially the other side of the same coin – this measures how easily sound “leaks” into and out of a given room.
2. Reinforcement of the desired sound is a term that refers to the ways that the audio from the performance area is amplified or reflected directly to the audience.
3. The distribution of sound is mostly a function of the shape of the event space, and to a lesser extent is affected by the interior wall design. Large, flat surfaces can negatively impact distribution, and need to be broken up by some dimensional elements.
4. Reverberation time is the most variable characteristic of auditoriums, and small changes in materials can mean the difference between perfect sound transmission and a jumbled mess of echoed speech. Crucially, the hard surfaces of certain stadiums can be extremely reflective and, therefore, disruptive.
Other Features
The effectiveness of the sound design may the single most important aspect of a given auditorium’s engineering, but the presenter’s comfort level and success is tied to various other factors as well.
Sloped floors, for instance, become exponentially more important for public speakers as their audience grows. After all, what kind of sense does it make to spend all your time making sure the audience can hear the stage if most of them can’t see it? Movie theaters learned this lesson years ago, as nowadays it would be difficult to find a screening room that did not offer the visually superior, more efficient, and more accessible stadium-style seating.
Lighting design is a complex enough topic that it deserves an essay of its own, but suffice to say that the ideal arena provides a means of spotlighting the stage and plenty of flexibility. The appropriate capacity is key, too, but the needs of every speaker and pitch are infinitely variable and there really is no perfect amount of people to speak to. A skilled presenter understands that sometimes we present to one person in an intimate setting, and sometimes we present to thousands. Finally, it’s a good idea to make a habit of checking that your room will be safe in case of emergency – that could include lighted exit paths, fire sprinklers or extinguishers, and proper signage.
Conclusion
So the ideal venue for public speakers and presenters is a full one, but also a safe one. It’s one that provides the appropriate amount of space for the audience in attendance, and optimizes that audience’s experience. That optimization can be done in a variety of ways, the foremost of which (when it comes to presentations, anyway), is acoustic engineering. Within acoustics, the disciplines of engineering, architecture, and design are combined to create the ideal experience for audiences – and presenters sure are thankful.
