Here are further details on the various services we offer:
When sound or vibration travels out-of-doors, through the air or ground between a source (factory, airplane, highway, etc.) to a receiver location (an office, home, etc.) we classify this as "environmental."Obviously there are specific instances of environmental noise and vibration that can be (and are) expanded upon below, but this is the general category.
Much of our work is done in this area.One might think that only "big business" uses acoustical engineers on projects, but our work is also been for neighborhood groups and even individuals.
Some jurisdictions have noise and vibration regulations that can be applied to a particular situation, whereas others do not.A municipality might have a regulation, but it may or may not be enforceable for technical reasons.
Of particular note are our environmental sound monitor systems.We have battery-powered devices that can be placed in many different locations, on utility poles, rooftops, etc., to measure and record sound levels for, if needed, many days.These devices can show, down to the second, what the sound level was at a particular time.This information can then be correlated with a log of activities and other measurements to calculate many of the metrics that are used in assessing environmental sound.For example, the "day-night sound level" is something used by the FAA for aircraft noise and by HUD for assessing housing.We sometimes use these instruments for site development to document existing conditions in an area before a new residential development, industrial site, etc. is built on the site."Before" and "after" measurements can show how much effect, if any, an operation imposes on a neighborhood.
This refers primarily to sound measured inside of a commercial or industrial operation.It principally is concerned with the noise exposure (both sound level and time duration) that workers get on the job.OSHA has standards regarding noise exposure and calls for engineering controls, a hearing protection program and other mitigating measures when excessive noise exposures can be found.
Beyond just noise exposure, however, there are other attributes to a noisy environment that may not be obvious.While the sound levels in an office may not be (and certainly shouldn’t be) as loud as might be found in a manufacturing area, high sound levels in an office can cause difficulty with understanding conversations in a meeting, in a telephone conversation, etc.Certainly high sound levels can interfere with concentration.Whether from outside sound sources or building HVAC systems, office noise can be a significant disturbance.
The sound that aircraft (fixed wing and helicopters) make in and out of airports and other operational areas is a concern to not only neighbors but also the operators of the aircraft.Someone might find it hard to believe, but many aircraft owners, especially people who operate helicopters, do make serious attempts to minimize neighborhood noise.There are flight procedures that can be utilized, and by planning approach and departure routes the effects on neighbors can be reduced.
We have done studies for individual aircraft owner/operators, state government for regional airport studies, and studies around several major international airports.
Besides adjusting flight routes, etc. to mitigate the noise, in the case of neighborhood schools and other sensitive receivers there are techniques that can be applied to reduce the interior sound levels to cut down on disturbance.For example, in a classroom frequent aircraft noise may be so substantial as to cause the teachers to have to stop teaching while a plane passes overhead.Through architectural and other controls these disturbing sounds can often be reduced.
For new aircraft operations we conduct studies to document existing sound levels and also to make projections of how the proposed operations will affect the existing sounds and what neighbors can expect to hear.In several instances we have helped communities develop noise regulations oriented around aircraft (helicopter in particular) operations.
Commercial and Industrial Noise to Residents
This is a version of environmental noise.In particular, noise regulations often apply to, specifically, residential receivers, so they are a special group.Obvious sources of sound might be industrial operations, but office buildings and shopping complexes, as well as highways, can also be significant sound sources unless controlled.
A common source of sound is heating, ventilating and air conditioning (HVAC) equipment on these various structures.With a shopping center potentially having many dozens of rooftop units, the combined effect can be significant if not addressed.On the other hand, there are mitigation measures that can be used, including selecting appropriate equipment as well as other control measures to reduce these sounds.There are also engineering tools that can be used to predict what the combined sound effect is from all of the operating equipment.
Associated with this would be motor vehicle operations at an office complex, industrial plant or shopping center.Needless to say, nighttime deliveries or the parking of refrigerated trailer trucks at a grocery store next to a residential area could be expected to create complaints if this is not addressed in the design and operation of the facility.We have in use analytical tools for investigating these matters, as well as conducting measurements if necessary.
Motor Vehicle and Railroad Noise
Noise from highways and rail operations is special.In some instances local or even Federal regulations exempt certain types of operations from enforcement activities.This doesn’t mean that things can’t be done, but it can complicate the issue.For example, rail operations along a right-of-way may be exempt, but rail yards, the parking of idling locomotives and other kinds of activities may be covered by regulation.In turn, railroads recognize the need to be good neighbors and do investigate issues.A proposed rail operation might be studied to determine the sound impact on the neighborhood and also what mitigation measures can be used and what effect those will have on the sound levels.
Motor vehicle operations are usually studied from the standpoint of traffic on a particular site, such as a shopping center, overnight shipping hub and the like.Vehicles on the public streets are generally exempt, except when new construction becomes a factor.Roadside noise barriers can provide benefit to certain residences, but they do not reduce noise for all people
The building or improvement (widening) of an existing street may trigger the need for noise control measures.On the other hand, if a residential development is going into a location near a highway, the developer may want to investigate the sound so that a determination can be made about what needs to be done in development to improve conditions for the residents, which, in turn could improve the marketing of the units.
This specialized branch of acoustics can cover quiet a few things; we do not do them all.The design of a music hall, for example, is not something we do because it is so specialized.However, the acoustical characteristics of offices, churches, schools and the like certainly are areas in which we work.By balancing the design of a room, selection of materials covering various walls and the ceiling, and the possible use of a sound reinforcement system, and working along with the architect, substantial improvements can often be made.
It is a common misconception that talking louder in a bad acoustical environment makes things better.We have seen this philosophy applied in offices and even in courtrooms.The problem is not one of loudness but rather speech intelligibility.In an acoustical environment with a lot of echoes, speaking louder, even using a sound reinforcement system, simply makes the unintelligible sound louder, not clearer.This, of course, affects understanding what is being said (maybe even leading to misunderstanding) and the ability of people to learn.Consequently, a good acoustical environment can be important in a school, office, conference room and even a courtroom.Imagine the effect of someone in a jury misunderstanding what a witness says because of the poor acoustics in the room.
Mechanical Systems Sound and Vibration
Sound and vibration comes about because something is vibrating.Whether it shakes the structure or ground it sits on, or transmits those vibrations though the air, determines whether it makes sound, vibration or both.Obviously, one way to reduce the sound and vibration that someone hears or feels is to reduce it at the source.
Our work with mechanical systems includes HVAC components, cooling towers, generators (including standby units), material handling, conveyors, and many other sources of sounds and vibrations.We often work with architects or other engineers to develop feasible, cost-effective control measures.In some instances it may be as simple as identifying what component on a particular device is making the sound and then aligning, replacing, improving or otherwise changing just the one thing, rather than, for example, completely enclosing a source.On the other hand, sometimes a substantial enclosure or barrier is needed.
Regulation Enforcement and Development
Although we are not a government agency, we have done work for individuals, municipalities, and other agencies to provide them with data that otherwise support their enforcement efforts.We have also helped develop noise regulations where none exist or existing regulations need to be modified.Part of the "trick" is to develop a regulation that is technically sound as well as one that addresses the problem.Simply setting a low sound level may cause problems in other areas, not just fix an existing problem.In one case we saw a municipality change their sound level limits in an attempt to control a manufacturing plant, only to find out that those limits also applied to all the other sources in town, including the municipality itself!As it turned out, the industrial operation they thought was making the noise wasn’t actually the one causing the problems, once it was investigated.The result was the municipality had to change its regulation another time.We also see many instances where municipalities, etc. copy a regulation from another jurisdiction.The problem with that is if the basic regulation or code is flawed, they’re simply repeating the same mistakes, with the result being an unenforceable regulation.
We have conducted training courses for industry and government for many years.Our staff developed and taught the Advanced Noise Control Course for the U. S. Department of Labor’s OSHA Training Institute for over a decade.We have presented courses for the Department of Defense as well as State and local agencies.For many years we taught week-long courses for a leading acoustical instrumentation manufacturer.
A quality sound level meter can be purchased for one or two thousand dollars.However, that does not make the operator skilled in its use.Just as any tool can be misused, so can measurements made with a sound level meter be substantially incorrect if not done properly.We have seen all too many instances where someone at a manufacturing plant or a local law enforcement officer buys a "sound level meter" from a local electronic store, only to find out later that the instrument cannot be calibrated, meets no recognized standard, and, in some instances, specifically cautions the user against using the device for enforcement.And this is before they even begin making measurements!How an instrument is used can affect the readings by five or ten decibels.Just as a police officer needs to know how to use a radar gun, or a surgeon needs to know how to use a scalpel, the proper use of sound and vibration measurement takes training and experience if it is to be done correctly.
Design and Installation of Noise Monitoring Systems
Our expertise with instrumentation and computers has been combined into our ability to design and building long-term, permanent noise monitoring systems.These can be placed in strategic areas and used to measure and record sound levels, generate alerts when certain conditions are met, and to document the sound in an area over time.In some instances these systems have been used to correlate sound in different areas to show what is or isn’t producing the sound.
These systems all use commercial components but are put together with application-specific software to control and operate the systems.They are usually connected together using wireless communications methods so that they can be spread out over, in some instances, several miles and still maintain second-by-second information into a central system.With monitors located in and around a noise source as well as in adjacent neighboring areas, suspected or alleged high sound levels can be documented or refuted.
Much of the above can be applied in legal proceedings.Besides conducting measurements to show whether an operation complies with a regulation or not, making measurements to assess how the sound or vibration in question compares to regulations or guidelines, and then testifying on all of this, falls into the area of forensic acoustics.We have testified in proceedings in front of local boards and courts, county, State and Federal courts, qualifying in all as an expert in acoustics.