The famous opening line of Ella Wheeler Wilcox’ poem Solitude reads: Laugh, and the world laughs with you. It’s a lovely image of shared mirth, and it turns out to be surprisingly true. Psychologists from Le Bon to Freud to Turner & Killian have studied the collective behavior of crowds over the past two centuries. Regardless of the theoretical underpinnings supporting their conclusions, each psychologist has observed that crowds of people act together as one unit in ways that cannot be predicted by looking at the prior behavior of each individual in isolation. Laughter, they observe, spreads in crowds as if it were contagious.

As it turns out laughter is—quite literally—contagious. Neuroscientists at the College of London reported, in a 2006 study, that when you hear the sound of laughter, a part of your brain “lights up” and prepares the muscles in your face to smile and get ready to laugh. If you have ever felt that upward twinge in your cheeks when you hear someone laughing hysterically at something you considered just mildly amusing, you know exactly how this feels. That same study found that you also have similar “mirror reflexes” for other positive sounds (cheering, and the like) though not so much for sounds with negative associations. Additional studies have even found that laughter occurs up to 30 times more frequently in social situations than when you are alone.

What we find, then, is that your response to positive experience is much stronger in a group than alone. This is one of the key things that cause live performances to be such powerful events. As laughter or applause ripples through a hall, the sound of the audience response around you helps to reinforce your own experience, and you respond accordingly. For any number of reasons, you will laugh and cheer in crowds more freely than when by yourself.

Actors are aware of this, of course, and they will subtly modify their performances based on the audience response that they hear. In a theater where a skilled actor can clearly hear the audience response, you end up with a feedback loop: the actor delivers a line, hears the audience response, modifies the upcoming lines ever-so-slightly to try to achieve more of the response they desire, the audience responds, actors adjust, and on and on. This is one important part of the “energy” that exists between performer and audience during a live performance that is not present during rehearsals.

You probably noticed, though, that there is one crucial feature that is necessary for all this to occur: everyone needs to be able to hear each other. In a theatre, it is obvious and indisputable that the audience needs to be able to hear the actor. As acousticians, we know that this is the #1 “pass/fail” issue in a theatre. However, if you design a theatre to that standard alone, you end up with a nicely appointed lecture hall. Whether introduced by accident or intentionally included in the design, the ability of the audience to hear one another responding to a performance has proven to be a key feature in the world’s best theatres.

There’s not much of a trick to it, really, but it is overlooked too often. For starters: Place as many hard surfaces as possible near the audience. It really starts out that simply. The floor? We see too many floors with carpets on them, when it would be better to have a hard floor finish (except the aisle, that is… carpet is fine there in a drama theatre). Seats? Too often padded upholstery is everywhere, even the parts you don’t sit on; the backside of the seat back and the underside of the seat pan can do wonders for audience response when they are hard surfaces (wood, metal, or plastic if you must). There are even a few additional things that can be considered in the seat design (seat back height, wood reveals around the front side of the back, etc.) when necessary.

There are also some room layouts that work better for propagating audience response. Wide, single floor spaces designed like cinemas are not terribly effective, as the response all tends to ripple forward towards the stage. Spaces with balconies and side boxes work much better, as the audience response sound moves from side to side, up and down, passing from one part of the audience to another.

Of course, all this assumes that everyone hears the actor’s lines in the first place. If you’ve ever sat in a theatre and realized that one half of the room is laughing at an apparent joke and the other half (who are looking at the actor’s back) are sitting there quizzical, then there is a much bigger problem. But that is another topic for another day (so check back soon for that one!).

The next time you go to a show, take a look around at the room as you find your seat. Will the sound of laughter and applause come at you from a number of directions? Are there a myriad of sound reflecting surfaces near you in your seat? If not, brace yourself… you may be in for an evening of feeling a bit more detached from the show than usual. You may feel like you’re the only one laughing, even when you’re not (and no one wants to be that person!). If the space is well suited to the audience, though, settle in and be ready to cheer as you can only when you’re in the midst of an attentive crowd.