The Art and Science of Good Sound Design

Whether your needs are as simple as amplifying announcements from the podium or as complex as balancing voices with instruments in a large space, paying attention to sound design can make or break your concert.

In anticipation of pleasing an audience, we develop a program we think will be engaging, we select a venue of appropriate size and location, and we choose production elements—attire, staging, lighting, positioning, choreography—that will help deliver a compelling performance they will long remember.

Often though, little attention is paid to what is, for a choral concert, arguably the single most important element for the audience—the sound. Months of painstaking preparation can be laid waste by inadequate preparation or execution of getting the sound to your audience. The tragedy is that many of the pitfalls can easily be avoided by paying attention to basic sound design.

Microphones

Even if your chorus has never amplified its concerts and has no plans to do so, there's likely a need for some sound design at its most fundamental level—the use of a microphone and amplification to make announcements, introduce a program, or host a dialogue with the performers as part of a before- or after-concert enrichment program. That is as deserving of the same level of advance planning and preparation as every other aspect of your performance.

Many choruses perform in venues without sound equipment or technicians but providing your own is not as hard as you might think. Good-sounding public address systems with sufficient power for small- to medium-sized venues have become much more affordable and easy to use in the last several years. For example, Fender—the same people who make electric guitars and amplifiers—have a line of rugged, portable, and powerful public address systems called Passport that start under $400 and are quite easy to set up and configure (used Passport systems are listed on eBay and elsewhere for even less).

Rental is another option. If you're not served by an audio equipment rental company in your area, online rentals are available through ATS Rentals, which will ship a portable PA system to any location in the continental US for low daily/weekend rates.

It's not enough to invest in the equipment, though. Someone needs to be trained in how to use it properly and given an opportunity to rehearse in the venue--along with the performers. Too many organizations leave operation of the sound board to a hapless volunteer at the last minute and then wonder why they come across as unprofessional when something goes wrong.

Saving money by using a volunteer only works when the volunteer is trained to do the job correctly and given support to do so. Investing in a sound technician could be the best option if a capable (and preferably experienced) volunteer is not available.

When to Hire a Sound Technician

For larger choruses performing in fully equipped concert venues, the sound design challenges and its solutions are usually more complicated. Depending on the complexity of your program and the challenges of your venue, you may need to consider consulting a sound technician to help you use the equipment to its fullest advantage.

Too many organizations leave operation of the sound board to a hapless volunteer at the last minute and then wonder why they come across as unprofessional when something goes wrong. Saving money by using a volunteer only works when the volunteer is trained to do the job correctly and given the support to do so.

"Getting the best sound is always a challenge, regardless of the circumstances," says Jeremy Satchell, assistant conductor of the Towne Singers and general manager of Hollywood Sound Systems, a prominent provider of audio systems for all manner of live performances throughout Southern California.

"A lot of times the audience is conditioned to expect audio problems," says Satchell. "Too many of us have attended over-amplified events where distortion and feedback are a chronic annoyance. So there can be a little tension in the air from the get-go. The other universal challenge is what I call 'ampliphobia'—the fear of having one's voice amplified. Public speaking is a frightful experience for many people, and the added prospect of being amplified only makes matters worse. Having to sing raises the bar even higher, of course."

Experts who coach in the field of public speaking provide pretty consistent guidelines for overcoming the "yips": Calm down. Be prepared. Think positive. And practice, practice, practice.

These same rules apply to public singing. And Satchell suggests a few others, based on his experience working with choirs and soloists. (He has assisted in sound design and audio production for an annual show choir showcase, with amplified performances that typically feature choreography, costuming, and fast-paced staging.)

"I go through a little primer on microphone technique each year to cover two vital points just prior to showtime," says Satchell. "The first is, sing naturally—don't make changes to volume, diction, or phrasing just because you're singing into a microphone. A microphone is much the same as a human ear, so you should sing to it just as if you're singing to another person."

"The second is, sing consciously into the microphone, not away from it. This is best explained with a demonstration. I have the kids sing 'on-mic' and 'off-mic' in rapid sequence so they can understand the huge difference it can make. It doesn't take long for them to get the message."

Having established a reasonable baseline for the soloists, the tasks remaining are to think through the elements that may contribute to or detract from audience engagement in and enjoyment of the program.

"The key question is always, 'What do we need to amplify?'" says Satchell. The answer is provided by consideration of the four elements that most affect the way the sound is heard by the audience: the space, the musicmakers, the equipment, and the configuration.

Architectural Acoustics

Space has a major bearing on sound design and the need for audio support (amplification), and there are three elements to assess when considering a performance space: shape, size, and materials.

The best performance spaces are designed in such as way so as to distribute and reflect sound equitably throughout the space. Carnegie Hall and other celebrated performance spaces are designed in a slightly oval shape with walls that have a fixed arc. That permits the sound to be reflected equally to all parts of the space. In addition, ceilings in top-of-the-line performance spaces are sometimes built in a convex shape to help project the sound back down to the listener without bias (that is, without hot spots or dead spots).

In many instances choruses are performing in spaces that have not been explicitly built to maximize acoustical properties. In assessing the liveliness of an unfamiliar space, a sound technician will perform a rudimentary test to assess the space's reverberation properties, the most useful benchmark for determining the need for audio amplification. Lots of reflective surfaces and relatively absorbing material (including people) makes for a good reverb.

"We usually choose a spot on the stage and another out in the audience, maybe 30 feet away," says Satchell. "We'll clap our hands together and then count the seconds until the reverberation from the sound dies away. A good reverberation tail is generally anything over two seconds. In such a case, you know you've got a pretty lively space and amplification needs are likely to be modest. Anything less than one second generally suggest that amplification and reverb should be added to the mix."

"A microphone is much the same as a human ear, so you should sing to it just as if you're singing to another person." -Jeremy Satchell, Towne Singers and Hollywood Sound Systems

Another key to assessing reverb in an unfamiliar space is choir tuning. If tuning the choir in a new space varies more than it does in the choir's regular rehearsal space it's probably because the singers can't hear each other in the manner to which they've become accustomed.

The sound is being dispersed and/or absorbed to a greater degree than they are accustomed to; the solution is to move singers closer together, or have them assemble in an arc facing inwards—or both. These configurations are subject to the constraints of the facility—whether risers are needed and options for moving them, to name just two.

Instrumentalists vs. Singers

Finding the right balance among the performers is another major issue. Most instrumentalists have a natural advantage over singers in volume potential (it's been said that one trumpet is, on average, the volume equivalent of six to eight singers). This can pose real challenges for audio techs, especially in the case of instrumentalists who aren't particularly interested in lowering their volume levels for the sake of the choir.

"I think the best practice is to make them self-policing," says Satchell. "I've found it works best to use monitors pointed directly at their heads. If the amplification is pointed away from them, they really have no practical vehicle for judging their relative volume. They tend to naturally raise the volume."

Equipment

Compromises are inevitable in the choice and deployment of supporting audio technologies. For instance, if it is desirable sound-wise to place a microphone in a position that could be objectionable to some members of the audience, you will probably want to find another solution.

Many performance venues utilize so-called "hanging microphones," which have both good and bad features. They're generally not ideal for choral amplification because they face straight down (and chorus members generally don't sing facing straight up). On the other hand, their downward-facing attitude means that they won't pick up an overly-aggressive church organ, nor will they pick up annoying buzzes or motor noises from nearby lighting fixtures.

Arranging Singers

Creativity in choir configuration and placement should be done with an understanding of the laws of physics as they relate to sound transmission.

Studies have shown that the human ear and brain cannot differentiate between sounds that are out of synchronization by up to five milliseconds, but that they can (and do) recognize as different those sounds that arrive at the ear more than five milliseconds apart. In a dry, temperate room (68 degrees F) sound travels at 1,125 feet per second, and that means that we can recognize audio as being out of sync if the sources are as little as six feet apart.

So the placement of groups of singers at disparate locations in a performance space can create head-scratching audio nightmares because the sounds coming from the different groups will be unlikely to arrive at audience members' ears at the same time. "You need a conductor who directs slightly ahead of the beat and chorus members who respond to the conductor's visual cues rather than audio cues," says Satchell. "That's a rare combination, and tough to pull off successfully."

Surprisingly, time of day can have a significant effect on audio requirements, requirements that can change during the course of a performance. Changes in both temperature and humidity affect the speed of sound and the acoustical properties of reflective surfaces and even some of the technologies used to bolster audio. Some loudspeaker systems employ wooden cones to project high frequencies, the throats of which can constrict or expand with varying temperature and humidity—this means the sound tech must adjust gain throughout the performance.


This article is adapted from The Voice, Winter 2010-11. 

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