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HOW LOUD IS TOO LOUD?
by David W. Scheirman

AN OVERVIEW OF SOUND SYSTEMS USED IN THE CONCERT INDUSTRY, LIKELY FUTURE DEVELOPMENTS REGARDING SOUND LEVELS AND ENVIRONMENTAL NOISE ISSUES
David W. Scheirman
Concert Sound Consultants
321 High School Rd. NE #252
Bainbridge Island, WA 98110
(206) 842-9876 phone (206) 780-5775 fax
Email - dsound@dsound.seanet.com

Introduction

Large portable concert sound systems have the ability to effectively communicate artistic values for large-group entertainment. The technical growth displayed in recent years in the field of large-scale sound reinforcement is impressive. However, only recently have internal, industry-specific control structures like formal training for system operators and peer group awareness of public health issues and community noise concerns been developed.

A situation now exists wherein the specialized technology's ability to deliver pleasure or pain has surpassed the larger society's ability to monitor or control the process. A concertgoer in search of entertainment can encounter aural bliss, or ear-shattering chaotic noise, or something in between. Large-scale concert sound is improving as distortion levels decrease and veteran system operators' skills improve. The concert sound system is seen by many to be a valid and crucial extension of a contemporary musical performance.

A Contemporary Challenge

Most contemporary music events feature sound that is of a much higher quality than was available a decade ago. Yet, for some individual listeners, audience groups and community environments, there are concerns. A concert event that features amplified music may not be totally compatible with local noise-control ordinances. Of course, the same could be said of carnivals, auto races, ball games and other forms of public entertainment. Outdoor concerts in particular can be perceived by some members of the surrounding community as being "too loud". And, as a recent headline proclaimed, "Supreme Court Accord: Rock Music Is Loud". (1) A recent Supreme Court case considered the issue of right to freedom of expression vs. a municipality's police power to control noise levels at concerts in public places. (2) In such situations, just how loud is too loud? Before such a judgment is made, we must first know more about the source of the alleged noise how it is generated and controlled, and how it fits into a greater cultural context. The challenge to the concert sound industry is to address this issue from within, and to create viable solutions that work. The challenge to the noise control engineering community is to better understand the nature of the live sound system, its operators, and the entertainment industry that it serves.

To that end, a look at the sound reinforcement technologies in use, the socio-economic and political processes that influence their use, and an examination of current patterns and future trends is presented here.

The Typical Large-Scale Concert Sound System

A typical portable concert sound reinforcement system comprises a set of integrated subsystems that have been specifically designed to function as a specialized, roadworthy tool for musically addressing large audience groups in both indoor and outdoor environments. In the United States during the past twenty-five years we have seen a shift from voice-quality to music-quality systems. Today, custom-built portable systems serve the entertainment industry. These are carried in semi-truck trailers and set up, used and removed on a daily basis.

Let's examine a typical custom touring system set up for use with amplified music, serving an average crowd size that exceeds 50,000 persons in outdoor stadium venues. Such temporary systems are the mainstay of a sound reinforcement industry that supports and enhances a wide variety of special events in our culture today. While the vast majority of events that place on a daily basis in auditoriums, arenas and outdoor locations are smaller than the one detailed here, the basic design format would be similar. The hypothetical system detailed here is a composite of typical available touring rigs in North America, Western Europe, Australia and Japan. This type of sound reinforcement technology is now being exported to other areas of the world as well, such as South America, Africa and Eastern Europe.

The typical system utilizes a stereo 4-way active electronic crossover with additional lowpass filter for subwoofers. It requires a 480V primary AC power supply with 120V or 240V 400-amp 3-phase dedicated electrical power distribution systems to energize up to 90 dual-channel solid-state power amplifiers. Each power amp is capable of delivering up to 1,200 watts per channel for a total system electrical power generating capacity of nearly 200 KvA (Kilovolt-Amperes).

Two different control stations are used to adjust the level and frequency response characteristics of the total system. These include a main mixing, or 'house' position and a stage area or 'monitor' position. The stage monitor system serves the artists. 40, 50, 60 or more microphone and direct signal lines are used.

A total of 152 modular speaker enclosures house the following transducers in the main system:

Bandpass Loudspeaker type Quantity

Very low Frequency (20-80Hz) 18" or 24" 48 units
Low Frequency (28-250Hz) 15" or 18" 256 units
Midrange Frequency (250-1.2kHz) 10" or 12" 384 units
Upper Mid Frequency (1.2k-8kHz) 2" driver w/horn 256 units
High Frequency (8kHz-20kHz) compression tweeter 384 units


The described system will perhaps require two 48' semi-trailer units for transport, and a locally-hired labor crew will assist four touring sound technicians in setup. Chain-motor hoists or forklifts will be used to stack the modular speaker cabinets. The entire system will be out of the trucks, up and ready for testing and preparation for the specific concert event within 4-8 hours, depending on the environment and access to the venue.

Such sound systems are usually under the direct control of employees hired by the equipment owner, or "sound company". The contracting event promoter or touring entertainment client will usually rely on these persons for system design format and operating parameters.

Noise Control Concerns

Such a system represents a million-dollar investment, and is usually operated in a conscientious and responsible manner. Depending on the musical genre under scrutiny, some systems are obviously operated at higher sound-pressure levels than others. If the sound system operator's style is well-suited to both program material and artist/audience expectations, most parties will enjoy "good sound". Problems can develop when the sound system and the event that it serves has an effect on the greater community environment. If the sound of the event is perceived on a recurring basis in areas outside the boundaries of the concert venue, isolated complaints can escalate into a regional legal dispute.

Noise control engineers should be aware that such disputes are often the result of class difference or cultural bias; for example, the specific entertainers or style of music may not be appreciated by some residents of adjacent neighborhoods, or there may be objections to increased area traffic flow, general crowd behavior, and such. In these instances, there is often an attempt to use noise-control ordinances to scale down the concert events' impact on the community.

Public Health Considerations

The measured sound-pressure levels within the audience area of a major rock concert using the system detailed herein may average 110dBA, with 118dBA peaks, more than two hundred feet away from the stage area where the speaker system is located. Federal safety guidelines warn that listening to sound measured at 110dBA SPL for more than half an hour can result in some temporary hearing loss.(3)

Yet, standing-room-only crowds will cheerfully position themselves directly in line with powerful speaker systems for hours at a time in rock concert settings. Sound-pressure levels in the front rows at a very loud rock concert can exceed 124dBA. Yet, the average person would normally consider 95dB SPL to be too loud (4). Listeners seem to be less critical of louder sounds when listening to music that they enjoy.

Musicians working on such stages often wear hearing protection devices. So do workers in related industries at the site (video cameramen, security personnel, and lighting technicians, for example). The actual sound system operators rarely use such protection, as it usually impairs their ability to perform their duties.

Hearing protection devices are rarely used by audience members who have come to enjoy the music; the awareness level of a potential hearing health hazard is very low among the listening public.

Current Patterns

Some general patterns can be identified in the touring sound industry, some of which will have an impact on the above concerns. These include the following:

• Loud music is readily accepted by youthful listeners
• Economic compensation for popular concert enterainers is increasing
• Touring Sound Systems are getting more powerful
• Low frequency reproduction technology is advancing rapidly.
• Powerful, full-bandwidth music systems are finding their way into more and more areas of our society
• New educational programs are being developed to sensitize sound system operators to noise control and health issues

The area most where these patterns are perhaps most noticeable is in the series of outdoor entertainment amphitheaters known to the entertainment industry as 'sheds', due to the partially-roofed simple building structures designed to serve audiences in the 10,000-20,000 person range. Often built to present classical music along with popular music styles, these venues are frequently located near residential neighborhoods and are thus more prone to experience neighborhood noise complaints than if the facility were isolated in a rural area. These facilities make up a minor part of the overall touring entertainment industry, but they constitute an important one, particularly in the summer season.

While most of these facilities rely on the touring sound systems that accompany musical groups to provide audio for the concert presentations, some of them do have installed 'house' systems. These are typically spurned by touring shows in favor of the hired system that travels with the show by truck. The systems used in this type of facility are perhaps one-third the size of the system detailed earlier in this paper.

Many of the amphitheaters have permanently installed or seasonally leased supplemental systems for the perimeter lawn areas located beyond the edge of permanent seating rows. These are almost always used by the visiting shows.

Some facilities have attempted to impose sound-pressure level limits in response to community pressure. The exact level at which a show can be operated without offending any parties inside the facility or in adjacent neighborhoods is difficult to determine, and can be the subject of lengthy and costly investigations. Few facilities of this type have found and met an ideal compromise that will serve the expressed needs of the touring musical shows and the surrounding neighborhood.

The number of these facilities is increasing, and more such venues are on architectural drawing boards. Yet, the issue of community impact of the noise levels generated by louder shows hosted by these facilities is still an active one. Sometimes, the ideal combination of leased sound system, architectural features and public-relations programs can defuse a difficult local situation.

In the future, noise control engineers can expect to encounter an increasing number of situations such as those described here, and undoubtedly new ways of meeting this challenge will be developed and worked into the fabric of the entertainment, sound and noise control industries.

Future Trends

With popular music having a strong impact on the younger generation, and with the 'Sixties' generation now firmly positioned in adulthood, there is a greater tolerance of 'loud' music than ever before. This leads to a polarization against more mature members of the society. This, when coupled with more powerful sound systems that are available to serve public events, can mean that there will be stronger pressure brought to bear on already-straining community relations near outdoor concert venues.

As economic compensation to entertainment artists increases, so does their ability to purchase and hire more extensive and powerful production systems to get their message across to their audiences. This includes not only staging and lighting faculties, but sound systems as well. Thus, situations can develop wherein counterculture groups that deviate from social norms are readily equipped with more powerful tools for communication to large audiences. This can accelerate social change and lead to rapid transformation of society, or it can create wider generational and cultural gaps.

Another trend that we can expect to see is the continuing improvement of low-bass speaker systems, and development of a better understanding within the sound industry of how to use the lower part of the audio spectrum for emotional impact. This means that the overall electrical power requirements for portable sound systems will continue to rise (At high SPL's, the lowest frequencies require roughly 100 times the energy needed to sound as loud as mid-high frequencies). (5)

The improvement of low-bass systems could mean that the sound of live shows can be leveled off and maintained at certain volume levels, yet still offer a dynamic sense of excitement that meets audience expectations. For this trend to move in the most healthful and manageable direction will require the application of more new and creative educational programs for soundmixers and system operators.

Conclusion

With full-bandwidth, powerful sound systems becoming more prevalent, the creation of community noise-control problems and crowd health hazards is a future possibility. This could lead to excessive governmental restrictions being imposed on communities, concertgoers, and the sound industry, leading to a negative economic impact for the entertainment and concert sound industries. To prevent this from happening, internal industry educational programs are already being instituted, and information on new technologies is being shared throughout the concert sound industry.

The author believes that the most appropriate way to ensure the responsible operation of high-powered commercial sound reinforcement systems will involve internal industry educational programs, not hastily-created, restrictive local or national legislation.

References

1. New York Times, Feb. 28th, 1989
2. Benjamin R. Ward, et. al. v. Rock Against Racism (Docket No. 88-226)
3. Wayne Harris, "Sound And Silence", Car Stereo Review, March/April 1989
4. Rick Chinn, "Volume Levels and Live Music", Stage & Studio, Feb. 1989
5. Mark Engebretson, Guest Editorial, "More Comes To M.O.R.", Recording Engineer/Producer Magazine, May 1989