Last updated: July 8, 2023
Advice by Tony Palermo, professional radio sound effects artist
One of the most effective sound effects you can employ for radio drama is the murmuring of a crowd--what is called "walla walla." Here's info on the theory and practice of this important sound effect.
Sound effects can be used both as actions performed by characters--fights, gunshots, running feet--and as background sounds to paint the scene--factory machines, crickets chirping, lapping waves... and groups of people talking, gasping, yelling, panicking, etc. These crowd sounds are easy to render--they're just vocalisms by your cast or sound effects crew--and help to add depth and realism to what can often be a sterile background that principal characters speak over.
Crowd backgrounds are an atmospheric mumbling known as walla walla. Walla is cheap and incredibly evocative in conjuring up barrooms, quilting bees, legislatures, pirate ships, etc. You can create convincing nightclubs with a few clinking glasses and plenty of cocktail crowd walla. The next time you're in a restaurant, take a moment to listen to how all the differing conversations mix into an indistinguishable jumble that can tell you the setting, the size of the room, temper of the crowd--even the time of day.
You may be tempted to just sneak a tape recorder into the restaurant and record a real crowd, but you'll have more control if you leave walla to your cast or sound effects crew. Walla stolen from real life may come off as just noise under your scripted dialogue. Pre-recorded walla from sound effects collections are often blandly generic. It is better to create the precise type of walla necessary and you can easily conduct that homemade walla to rise and fall as the action demands. If a fight breaks out in your radio-scripted restaurant, your custom walla can erupt right along with it.
Good crowd sounds for radio require non-distinct mumbling punctuated with a few real words, some laughs, coughs, etc., but you don't just carry on multiple real conversations at a low volume. American radio dramatists call this mumbling "walla," while in the U.K. it's called "rhubarb," in Germany, "rhabarber." The story goes that crowd backgrounds sound like a group saying "walla walla walla," but it's really just the practice of using nonsense syllables. I've heard productions where people will literally mumble the words "walla walla walla walla"--or "rhubarb, rhubarb, rhubarb" which is cute, but can often be heard for what it is, which immediately appears fake to the listener. Don't risk getting caught. It's better just to mumble animatedly, reproducing the inflections and fluctuations of conversation--without much use of real phrases.
I've heard of some producers breaking walla voices into two groups. One will repeatedly say, "peas and carrots" while the second group replies, "ugamumble". With both these phrases mixing, the result is an unintelligible murmur. Other strategies include reciting the alphabet, but I suggest walla actors just grumble and mumble with little peaks and pauses to simulate speech. They should also laugh or cough occasionally, as the scene calls for it.
Film and television sound design has a different approach to walla. They use real words and avoid mumbling. They even employ full sentences and some producers encourage professional "walla groups" to create little conversations based on research about locale, time period, etc. However, in a film, the screen is showing the principal actors as they speak, focusing the audience's attention on what is being said. Film walla is done in post-production so technicians can also easily mix down the separately recorded walla tracks so the main dialogue is easy to hear. Radio walla is different.
Radio has no visual close-ups to focus the listener's attention, so real phrases in the walla can easily steal the focus from the scripted dialogue. And radio walla is usually recorded at the same time the principals are speaking--and often just a bit distant from the main mics. Film-style walla, with its distinct conversations, is ill-suited to the unique relationship between radio drama and the listener. That's why radio walla uses indistinct mumbling. You don't want a walla quip or phrase to break above the murmur or into a pause by the foreground characters. That could divert the listener and even step on an important line of dialogue, thus harming the story. As in many other areas, radio technique differs from those used for visual storytelling. So, let radio be radio and remember to mumble.
When scripting radio dramas, I treat walla as a sound effect--which it is. You can intersperse it with sound cues or break walla out into its own separate cues. Be descriptive with walla. Treat it like a character. Give the crowd an attitude. I often script exact words to be ad-libbed into the walla, keeping it "on-topic" and not just generic mumbling. And, there are many types of crowds: sports fans, jetliner passengers, fighting armies, pygmy tribes, buffaloes being stampeded off a cliff, etc. It's not just "walla." As with other sound effects cues, be precise with your instructions.
Here are some typical radio script cues with walla:
SOUND: PLATES/FORKS. WALLA--DINNER. WINE GLASS TAPS (3X). WALLA--HUSH.
WALLA: WALLA--(GASP) AD-LIB: "WHAT?" "OH MY!" "HEAVENS NO!"
SOUND: FIGHT BELL RINGS (2X). WALLA--FIGHT CROWD--CONTINUE UNDER.
SOUND: WALLA--NITE-CLUB--UNDER WHOLE SCENE. GLASSES CLINKING.
WALLA: WALLA--HUBBUB--”WHAT?” “AT THIS HOUR?” "AN OUTRAGE!"
SOUND: WADING THRU
OCEAN OF BONES. WALLA--FRIGHTENED CRUSADERS.
Before copying scripts for the actors and sound effects artists, I mark up my master script by circling all the walla parts so they'll stand out. I also compile walla parts into a separate list so I can explain what I want to cast and SFX crew quickly.
Before we begin running through the script at rehearsal, I'll go over the list of walla parts with cast and crew and demonstrate they kind of effects I want. For example, "In scene two, we're in a train station. I need travelers murmuring in a really big space, so stand way back from the mics." Or, "As the crusaders wade through the ocean of bones, I want frightened men. Throw in some shivers and teeth chattering, even some whimpering. There are 100 crusaders here, so everyone can walla."
I also trim down the number of walla voices needed as the crowd size dictates. I may pick certain actors to do walla in a scene and have everyone mark their scripts as to whether they're doing walla at particular cues.
Most importantly, I always explain, "A little walla goes a long way, so keep it low and watch for my cues to bring it up, down or cut it out." If the walla voices are too loud, they can overwhelm the scripted dialogue and even make it hard for the sound effects crew to hear the dialogue--causing them to flub important SFX cues. Loud walla also forces the foreground actors to speak louder--just to be heard over the din--and that can ruin the desired effect of one character speaking to another--with a crowd in the background.
I've found that walla should always be lower than what performers expect. Left to themselves, actors chatter away at too loud a level. They seem to think the engineer will balance the mix with a knob, but the environment of the studio or stage should be where you control the balance. Radio drama performance hinges on the performers listening to each other, so try to make things easily heard and that means keeping the walla down. Big crowds are more people talking, not people talking louder. It isn't the volume, but the multiple mumbling that is essential. Volume is a function of distance and in radio, we can put that crowd as far back from the main voices as we want. It'll never appear unreal because the listener can never see the size of the crowd or how close they are to the main voices. Thus, once you have 5 or 10 walla voices going, the audience will only think: crowd--no matter how big you say it is.
Walla is a background sound, so have the walla voices off mic to add ambience. Also, have walla parts performed by actors who are not otherwise speaking in the scene. You don't want people mumbling too close to the main microphones. There'll be a disparity in ambiance and their mumbling may be detected by listeners--as mumbling.
Since I direct radio drama "on the floor" just a few feet in front of my cast, I lead the walla myself, mumbling along and using hand gestures to indicate volume and intensity. I find this conducting approach very effective, as I can totally shape the nature of the walla and sustain it though long scenes. If you direct from a glass control booth or from a chair far from the stage, you may have some difficulty in getting your hand signals for walla cues noticed. Many actors tend to start off a scene with good walla and then let it fade down or even die. Be careful to keep it going. When explaining the walla, go over the hand cues to raise or lower volume, vary the intensity and cut it out completely.
I sometimes prepare a separate script, just for walla. I use colored highlighters to indicate when a walla cue begins and then draw a vertical line through all the other dialogue, sound, and music cues to indicate how long that walla runs. In performance, I'll give this walla book to some extra people in the studio and have them do nothing but walla. You can also hand out a special highlighter--say purple--and have your regular actors mark up their scripts for just the walla parts.
To prove just how powerful a tool walla can be, the next time you rehearse a scene set in some public place, do it once without walla and then again with walla and notice how that scene comes alive. You don't want to overuse the effect, but there's a realism that walla contributes that can't be beat by even the most emotive foreground actors working alone or by any amount of pre-recorded walla sound effects. Walla can be employed to break your drama out of the studio and expand your listener's theater of the imagination to fill an entire world. So unleash the Mongol hordes, to the cheering of thousands!