- Apply acoustical foam or fiberglass blankets to ceilings and walls of room.
- Maximum noise reduction: 6-9 decibels (30-40% decrease in loudness).
- Advantages: No inconvenience to workers.
- Disadvantages: 75% of the room must be treated regardless of the size of the noise source.
- What materials? Hanging acoustical baffles from the ceiling, walls to be covered by acoustical foam or quilted fiberglass blankets.
- Apply acoustical foam or fiberglass blankets behind the noise source.
- Maximum noise reduction: 1-2 decibels if noise sprays noise our into room, 4-6 decibels if noise is sprayed directly onto wall (such as noisy vent on the back of the machine).
- Advantages: No inconvenience to workers
- How much foam? Treat the wall behind the machine with about twice the square footage of the “shadows” of the machine on the wall.
- Build an acoustical curtain system around the noise source.
- Maximum noise reduction: 6-15 decibels.
- Advantages: Very good noise reduction.
- Concerns: May have to incorporate view window for visibility and/or sliding panels for access.
- What size? At a minimum, 8′ high. Typically they should be double the height of the noise source.
- Build a complete enclosure.
- Noise reduction: Up to 20-30 decibels.
- Advantages: Maximum noise reduction.
- Concerns: May have to incorporate view windows for visibility and/or doors for access as well as ventilation baffle(s) for air flow.
A note on decibels:
- A 5 decibel noise reduction represents a reduction of 50% of the acoustical energy produced by the noise source.
- OSHA also states that a 5 db noise reduction represents a 50% decrease in the risk of hearing loss. (Noises reduced by 5 decibels sound about 30% quieter.)
- A 10 decibel reduction represents a 90% decrease in acoustical energy and sounds half as loud.