Expert Viewpoint: Reverb Matters
Jan 1, 2009 12:00 PM, By Peter Janis
Making money with acoustics.
There are tremendous business opportunities in the field of acoustics for sound contractors. The obvious markets are music schools, gymnasiums, and houses of worship. But there are many more: cafeterias, museums, call centers, dance studios, libraries, classrooms, and industrial applications. In fact, if you actually stop and think about it, the market for acoustics is absolutely huge — but it remains largely untapped.
What few contractors realize is that the science known as “acoustics” is actually not that complex. More importantly, as an audio specialist, you have a tremendous advantage over the typical drywall contractor: You know how sound actually behaves. For instance, you know that high frequencies with their short wavelengths are more directional, and therefore, they can be controlled using simple vectors. You also know that in a PA system, it takes about 20 times more power to drive a low-frequency bass driver to get those long, low-frequency waves to move. This tells you that controlling bass will require a whole lot more effort than controlling high frequencies. So for now, forget about managing bass — it's hard and often impossible. Focus your efforts on the easier-to-pick fruit, where sound becomes directional above 400Hz. This happens to be where the voice-communication range starts — another important piece of knowledge you should hold.
The markets can be broken out into four basic categories: industrial, commercial, institutional, and music-related.
This category includes bottling plants, printing presses, metal fabricators, wood shops, and other noisy industrial environments. The key motivator in this market is industrial safety. The Occupational Safety and Health Administration (OSHA) established a standard that requires industry facilities to implement a noise-monitoring program when exposure to noise exceeds an 8-hour average of 85dBA.
Safety also comes in the form of communication. If someone yells, ‘Be careful — a grand piano is about to drop on your head,’ and you do not hear the call, someone can get hurt. Treatment in such environments is usually in the form of acoustic panels spread around the perimeter to control the reverberant field and increasing the density of the acoustic panels around offending equipment. The easy way to identify an industrial customer is to get yourself a noise-decibel-level meter and offer the local industrial community a free sound-measurement test. Make up a simple chart with, say, 12 readings, and have a second page with grid paper to sketch the floor plan. Walk around the plant with your meter and write down your decibel readings in the various areas. If the noise level is above 85dB, you are potentially in the money.
This category includes boardrooms, call centers, cafeterias, lobbies, restaurants, health clubs, community centers, houses of worship, airports, and arenas. Ninety-five percent of the acoustic problems in these markets are voice- or communication-related. Increasing the size of the PA system will generally cause more harm than good in such situations. Simply stated, the problem has to do with too much echo in the room, which makes it impossible for the brain to discern the information being broadcast.
To improve intelligibility, you have to reduce the echo. Once again, treatment is a matter of strategically placing acoustic panels on the walls or hanging them from the ceiling to reduce the RT60, or reverberant time of the room. The more acoustic panels you put up, the less reverb you will have. For voice, an RT60 of less than 1 second is preferred. A simple clicker (or hand clap) with a stopwatch is all you need to evaluate the problem. If the echo lasts beyond a couple of seconds, you have a new customer.
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