MB Industries L.L.C. Blast Resistant Buildings & Ballistic Resistant Buildings

An import design feature of every MBI Building is sound quieting. We use top grade materials and special construction techniques that will provide you a functionally quiet building that will remain quiet even when the building is placed in a noisy environment.

Interior building noise from the MBI provided air conditioning system is nominally 60 dB. Therefore the external building sound field is usually the driving condition on the interior sound levels. Placing the building mounted HVAC away from the external sound direction will help interior levels.

Reflective interior noise (echo) is generally not a problem in MBI building due to the use of anti-reflective acoustic ceilings.

2. When it comes to sound, a dB is a Sound Pressure Level (SPL) referenced to 20 u-pascal.

40 dB is a library
60 dB is a normal home
65 dB is a busy office
85 dB requires a company OSHA hearing program
90 dB is a loud mechanical unit and has an 8 hour stay time. Work in this area would require hearing protection.

Protection against the effects of noise exposure shall be provided when the sound levels exceed those shown in Table G-16 when measured on the A scale of a standard sound level meter at slow response. When noise levels are determined by octave band analysis, the equivalent A-weighted sound level may be determined as follows:

Equivalent sound level contours. Octave band sound pressure levels may be converted to the equivalent A-weighted sound level by plotting them on this graph and noting the A-weighted sound level corresponding to the point of highest penetration into the sound level contours. This equivalent A-weighted sound level, which may differ from the actual A-weighted sound level of the noise, is used to determine exposure limits.

When employees are subjected to sound exceeding those listed in Table G-16, feasible administrative or engineering controls shall be utilized. If such controls fail to reduce sound levels within the levels of Table G-16, personal protective equipment shall be provided and used to reduce sound levels within the levels of the table.

Whenever feasible, employers are required to reduce the noise at the source through engineering solutions. When this is not possible or economically feasible it is acceptable to use hearing protection as a temporary solution. The term hearing conservation as defined by OSHA includes the following aspects, which the employer is responsible to carry out:

Monitoring of the noise environment. If the TWA (Time Weighted Average) noise level is exceeding 85 dB(A), a hearing conservation program is required.
Selecting hearing protection devices appropriate for the environment or environments at hand. Several different types of hearing protectors are required to be offered to the employees, in order to introduce a level of personal choice. The employer is responsible to pay for the original equipment as well as replacements. The employees are required to use the hearing protection, and the employer is responsible for the enforcement.
Training and educating employees in the proper use of hearing protection, the importance of full time use of hearing protectors when working in a noisy environment. Education and training is considered an essential and ongoing activity.
Establishing a baseline audiogram for each noise exposed employee, and annual hearing tests thereafter in order to monitor the hearing health of the employees. Have the audiograms evaluated by an audiologist or physician.
Take corrective action when it is concluded that a noise induced hearing damage is occurring. Corrective action can entail further education and training in the use and importance of full time use of hearing protection. Seeking the use of hearing protectors better suited to the environment and the individual. Using, what is called administrative controls, which simply means to reduce the exposure time for the employee in question. If these efforts fail, an employee may be transferred to a quieter job.
The above summary of OSHA’s hearing conservation requirements is not intended to be complete. The complete regulation (29CFR-1910.95) is available on the internet.

It addition to our standard sound protection package, addition sound protection can be engineered and provided by MBI. This can include the following upgrades.

Noise