Venue Acoustics On Tour

Pity the poor touring concert pianist. Each venue will provide the pianist with an instrument, and little chance to alter its tonal qualities or playing characteristics. The pianist must give the audience the performance they paid for, with little control over the very device that creates the sound. An excellent piano offers an opportunity to realize the performer's full potential. However, a poor instrument will be difficult to excuse to an entire concert hall of eager fans. When the audience leaves, they may have no idea whether this venue was the pianist's dream or nightmare.

This situation should be familiar to anyone working in live sound. Whatever the quality of the sound system, it can only be heard by the audience after the influence of the venue's acoustics. If the acoustics do not favor the style of the music (or in too many situations -- any music) then the audience will never hear the show the way it was intended. While this can often be frustrating to even the most qualified FOH sound mixer, it can be disastrous to those that heed the "old roadies tales" of venue acoustics.

My favorite "old roadie tale" is the one that offers a solution to excess reverberation. "If the room is too reverberant you must turn up the volume until the rig overpowers the reverberation." An interesting premise. With enough power, a sound system can tame those echoey sports arenas, cavernous clubs and cacophonous community halls! You wish ...

On the one hand, those of a more scientific bent understand reverberation to maintain a linear relationship to the sound power produced by the sound source. As the source rises in volume, so too does the level of the reverberation. On the other hand, our perception of reverberation is definitely non-linear. At lower sound levels, the late reverberant energy may be masked by the background noise of the venue. At extremely high volumes, the human ear's natural protection mechanism will react like a compressor. This may actually increase the perceived reverberation in a similar manner to the way compression increases the apparent level of microphone leakage.

The result is most likely to be the reverse of this "old roadie tale", as the rig is pushed to towards the pain threshold, the perceived reverberation will actually increase. Unless, of course, the sound system's protection limiting dramatically reduces the transients in the mix. Then the most obvious cues to reverberation, transients, have be squashed to the point that they no longer trigger the obvious aspects of the rooms decay. Not exactly an improvement in the overall sound quality of the show but a slight reduction in the sense of room reverberation.

Anyone that has tried to install enough acoustic treatment into a venue to tame the acoustics knows how impractical these physical measures are to take on the road. Instead, it is necessary to be careful in the selection of loudspeakers used and be very selective in the orientation of each device in an array. Stacking the same 10 boxes on each side of the stage, in each venue, is the best way to ensure the room acoustics rule the sound of the show.

If you are suspicious that a tour will include problematic venue acoustics, ensure that you have a sufficient range of loudspeaker coverage patterns available within the selection of boxes you take with you. Highly directional loudspeakers can allow you to reduce the sound that is directed at walls, ceilings, and back on to the stage. If the first thing that the direct sound hits is the audience, the room acoustics will have the least impact on the sound of the show. Couple this with the ability to trim the low-frequency devices to lessen the excess coverage/output in the low end and you may have fewer bad nights on the road. You will need the resources to carefully select loudspeakers for the tour. Even more important, you will need the time, during the load in, to develop a suitable configuration for each venue.

This is an excellent situation for computer control of the system amplifiers. If you can quickly shade the levels (and even better the frequency spectrum and signal delay) for each loudspeaker component, you will have a better chance of maintaining good audience coverage while reducing the spill onto surfaces in the building that will increase the level of reverberation. The trickiest part in all of this is the lobing produced by interaction between loudspeakers. Horn design, driver spacing and cabinet orientation will interact in an array to generate frequency dependent lobes in the coverage pattern of the array. These are often the cause of bad reverberation in a venue. The lobes may send narrow bands of sound energy off at odd angles. The result is a weird quality to the reverberation of the venue that makes it all the more obvious to the listener.

It is not easy to effectively cope with unsuitable room acoustics when on tour. So many variables will work against you, not the least of which is the time you have to deal with these thorny issues and still be ready for sound check. However, during your next sound check, try and take a few minutes to walk around the venue and listen to how your rig is interacting with the room. You may see potential for changing the configuration for tomorrow's show.

United Entertainment Media Inc.
460 Park Avenue South, 9th Floor
New York, NY, 10016
Ph. 212-378-0400
FAX 212-378-2160

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