J & A Enterprises, Inc.
Noise and Vibration Control Engineers

16 Broadway
Salem, MA 01970
01 + 978-741-1551
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All J&A projects can be subdivided into two major categories:

  • Existing noise and vibration problem solving, and
  • Design of preventive noise and vibration control treatments and solutions.

For resolving existing problems, J&A has at its disposal the proper instrumentation to fully diagnose the problem and give suggestions and recommendations for mitigation treatments. J&A will compare the existing noise and/or vibration levels with the levels allowed by appropriate noise/vibration standards and regulations (if applicable), and design treatments enabling compliance with the set noise and vibration targets.

For the new projects, in order to prevent noise and vibration problems from the outset, J&A will work in close contact with the manufacturer, owner, or builder providing necessary input at the early stages of this project, and supervising the implementation of the treatments throughout the construction.

If requested J&A will help establishing realistic noise targets to be achieved for a project. J&A will act as an expert witness on noise and vibration issues.

There are several types of calls that come to J&A concerning noise and vibration control.

  • There is the manufacturer who needs to make his product quieter in order to comply with international noise/vibration standards, and successfully compete on increasingly demanding world and local markets.
  • There is the industrial enterprise seeking compliance with the OSHA's or other regulations setting requirements for the workspace; or seeking to lessen noise impact of their operation activities on the residential neighborhood.
  • There is the client who wishes to control noise and vibration within his personal living space.
  • There is the organization that would like to optimize acoustical characteristics within their building, be it a school (with the new stringent requirements for the core and ancillary learning spaces), a business's auditorium or a doctor's office spaces.
  • There is the client who wishes to shelter his or her home from the noise of a busy street, or the neighbor's noisy air conditioning unit.
  • There are neighbors who register complaints when objectionable noise and vibration encroach from an outside source (be it voices and music from the neighboring apartment, or footfall noise from the room above; or some construction work being done in the neighborhood).
  • There is a municipality that needs a traffic noise impact survey, and the solution to mitigate traffic noise impact on the community; or that requires a predictive noise study, if a truck stop or an enterprises is planned to be built in the area.

When acoustical disputes arise, there are two major actions that J&A will commonly take to develop recommendations informing the client of his options.

First, acoustical measurements are taken of the existing noise and vibration problem. Questions to be asked are:

  1. What equipment is being used and what is its location relative to living spaces?
  2. Are there some parts of the equipment that are a greater source of noise and vibration than others? For example, in an air conditioning system there are fans and compressors. The problem may be emanating from either or both parts of the machinery.
  3. Knowing the brand of machinery and contacting the manufacturer for history, model standards, and steps the manufacturer may have taken to solve the problem are areas to be investigated.
  4. What are the decibel levels at the site and at points radiating from the site?
  5. What specific products already exist or can be tailor-made to mitigate the problem?

Secondly, it is important to research the state and local regulations for standards relating to noise control between properties. The question has to be asked, "Is there a legitimate basis for complaint?"

Whether there are legal grounds for action or not, J&A can recommend products and procedures that will quiet the offending source of the aggravation in the most cost effective manner possible. When possible we try giving several levels of noise and vibration control solutions for the client to select the treatments he sees as most satisfactory within the existing budget.

Examples of Past Projects

Environmental Monitoring - Lewiston, ME
In late 2011 J&A Enterprises completed an environmental monitoring project for the in-water noise during a marine construction project. The US Army Corps of Engineers required that specified in-water noise levels (SEL, and Peak Levels) should not be exceeded during marine pile driving operations. The in -water noise limits were mandated for the protection of endangered marine species inhabiting the waters at the job site. J&A engineer Aaron Korby deployed to the construction site during pile driving operations to monitor the underwater sound levels in accordance with the US Army Corps requirements.

Korby observed that piles installed with a vibratory pile driver were all safely within the environmental noise limits required by the Corps. However piles installed by impact driving were approaching the allowable noise levels. It was suggested that the construction contractor should employ underwater noise mitigation by using an unrestricted bubble screen from compressed air. This technique reduced the in water sound levels to within the specified limits. In deeper water where the noise situation was more severe, the compressed air hose was changed to a more effective configuration having more perforations of a smaller diameter. The effects of water depth and tidal current were noted over the course of the pile installation. J&A provided the contractor with a complete technical report to document the measured in-water sound levels of all the piles in order to demonstrate compliance with the permit requirements. Report contains comparison of in-water noise spectra during pile driving with vibro-hammer and with drop-hammer; and with and without noise mitigating treatments, showing the effectiveness of these treatments.

J&A has the capability to provide similar in-water noise monitoring services for other marine construction projects throughout the US and in other regions. Depending on the sensitivity of the habitat and the environmental conditions, such monitoring services might be required by authorities for variety of construction projects such as offshore wind-farms, marine terminals, waterfront projects, pipeline installation, bridges, or transmission tower installation. Please contact J&A Enterprises at 978-741-1551 to discuss the requirements of your project.

Machinery Noise and Vibration Evaluation - Smithfield, RI
Many products and machines sold in the European Union (EU) are required to meet stringent noise and vibration standards as determined by the European Community (CE). A globally recognized, EU notifying body, TUV, approves results of acoustic testing in order to demonstrate that machinery meets requirements. J&A has gained approval for its professional testing capabilities and certified instrumentation by TUV to conduct Annex VI sound power testing on certain construction machinery for the CE Certification.

Residential Complex - Newton, MA
J&A was hired to address several noise problems in the newly built residential complex in Newton. Several Carrier air conditioning units caused complaints of the residents of the complex and their neighbors. The noise exceeded State of Massachusetts and City of Newton noise regulations. J&A designed full gazebo-type enclosures with the air intake and discharge silencers, which dramatically reduced the noise to the levels allowed by the noise ordinances. The solution took into account stringent Carrier requirements for the allowed increase of the backpressure for the a/c units’ fans.

Food Plant - Lowell, MA
The plant’s rooftop incinerator generated high levels of noise in the neighborhood. J&A has determined that elevated noise levels were largely due to the incinerator blower. The uncharacteristically high aerodynamic noise was indicative of the blower unbalance. Balancing of the blower reduced noise dramatically and eliminated the need for the construction of intended noise barrier.

Air Compressor
A pre-production unit of a small compressor intended for hospital environment was submitted to J&A for noise treatment design. J&A proposed extensive restructuring of the unit architecture, selected low-noise cooling fan, determined its optimal position inside the casing by monitoring temperature of the bearing, head and motor casing. Proper ventilation, alongside with noise and vibration isolation and damping treatments enabled J&A to reduce noise by 18 dB(A). J&A’s affiliate company Soundown Corporation supplies precut insulation as designed by J&A for the production series of the unit.

Land Based Very Quiet Generator Set:
J&A supplied three 15kW generators for mounting on trucks used in an acoustic surveillance program. The generators had to have very low noise emissions even at low frequencies. J&A selected a commercial generator, and made substantial modifications to the exhaust, intake, ventilation, enclosure and mounting in order to achieve the specification.

Newton, MA
J&A was hired to design treatments for complying with OSHA noise regulations at the workstations of one of the Bayer’s plants. Our noise measurements showed that the main noise excesses were due to the operation of the vacuum pumps. Complete enclosures for the two types of pumps were designed. The enclosures incorporated silenced air intake and air discharge for the normal aspiration of the enclosed pumps, as well as the additional fans selected prevent the pumps from overheating.

College Residential House - Cambridge, MA
A two family house in Cambridge, MA housing professors had poor noise isolations, which was causing friction between the neighbors. J&A has developed noise insulation treatment and has supervised its installation. Both neighbors were quite pleased with the results of improvements.

Diesel Truck Stop - City of Portsmouth, NH
Under the contract with the City of Portsmouth, J&A conducted an extensive noise survey (including 24-hour noise measurements and monitoring of activities) of a diesel Truck Stop on US Route #1 in Portsmouth, NH. Working with the City’s Planning Department, J&A conducted a preliminary noise impact study: met with the residents adjacent to the site, developed and distributed a questionnaire among the residents to assess the perceived severity of the noise problem. Noise of various noise sources was measured and studied (refrigeration truck units, idling engines, pneumatic tools used for tire change, truck air brake release, noise of truck horns, etc.). The report containing the results of the findings, comparison to the City’s Zoning Ordinance, EPA and Federal Highway Administration guidelines and regulations, as well as the design of the noise mitigating treatments, was submitted to the City (each recommendation was accompanied with predicted noise levels, and approximate cost of the treatment). The findings of the survey were presented to the City Council, Planning and Public Works Departments at an open meeting with residents present. Written response to the residents’ questions was submitted to the Planning Department as a follow-up of the meeting.

Swampscott church steeple picureChurch Chimes
A church in Swampscott, MA has installed chimes marking each quarter of the hour. A big residential area was affected by the sound considered by some residents as intrusive. J&A was invited to resolve the dispute. J&A has developed a system of screens redirecting the chime sound away from the residential area. The church has also agreed to the J&A proposal to modify the chimes marking only one-hour intervals. The church clergy and the residents considered both these measures a reasonable compromise.

Mobile Carrier Manufacturer - Auburn, MA
On several occasions J&A was hired to design noise control treatments for the new generation of mobile carriers equipped with generators, fans and other noisy equipment. J&A specified exhaust silencers to be used with a particular type of equipment and designed air intake attenuators and soundproof enclosures to keep the noise inside the vehicles and outside noise pollution within the required limits.

Emergency Generator Noise Pollution - Hartford, CT
A neighbor complained of the noise of the emergency generator installed in a building of an insurance company in Hartford, CT. J&A was hired to document noise emission at the property line and design measures to reduce noise pollution. Noise barriers and air intake silencers designed by J&A have provided significant noise reduction and stopped the neighbors’ complaints.