The Best Foams to Reduce Noise

Acoustic foam has long been used in both marine and industrial applications to help decrease noise, reduce vibrations and protect workers. Sound abatement foam has been used by boat manufacturers to not only isolate but also attenuate sound and vibrations from marine engines while other sound deadening foams have been used in a variety of industrial environments to reduce noise pollution and also create a safer environment for workers.
The science of how sound reduction foam works is outlined below.

Do you want sound absorbing or sound blocking?

The difference between sound absorbing and sound blocking is most easily depicted in how a recording studio’s foam lined walls work. You might think that that foam is absorbing the sound but that is not the case. The open cell foam that is being used on these walls allows sound waves to pass right through them. In order to block the sound the foam would need to be heavy and dense to stop the sound waves from passing through. Acoustic foam is used to reduce the echo and reverberations that would otherwise cause problems with the recording. It does not block the sound from escaping the room.

Foam plays a large role in reducing noise and vibrations in many settings, and both open and closed cell foams can be used to control the acoustics of a room. 

Sound Control Foams

Foam that have the ability to absorb sound are excellent for marine applications where a loud, vibrating motor would make the experience uncomfortable. Without marine foam the engine would ruin the boating experience.

Closed-cell cross linked polyethylene foam is the ideal solution for these types of applications because this dense foam absorbs and blocks sound, creating a better experience for boat passengers. 

In industrial environments, both closed-cell sound deadening foam and open-cell foams are used to create a safer environment for workers. Closed cell foam products are used to block sounds and reduce the sounds in an environment, while open cell foams are used to prevent sounds from reverberating across a room. Both can be helpful in controlling and reducing the noise in a given area, which can help meet OSHA regulations on noise control.  

Noise requirements from OSHA

It is important to be aware of the OSHA requirements for employers. OSHA requires a hearing conservation program when noise exposure is at or above 85 decibels averaged over 8 working hours, or an 8-hour time-weighted average (TWA). Under OSHA’s Noise Standard, the employer must reduce noise exposure through engineering controls, administrative controls, or Hearing Protection Devices (HPDs) to attenuate the occupational noise received by the employee’s ears.  A combined open cell and closed cell foam application is a good start towards meeting those requirements.

Choosing Between Anti-Static and Conductive Foams

Special ESD foam that protects static-sensitive electronic devices, components, and parts for shipping and storage is a necessary solution for many of today’s devices.  When choosing a foam for these types of items, it’s best to ensure that they meet EIA-541 Packaging Material Standards for ESD Sensitive Items. When it comes to choosing between anti-static and conductive foams, it helps to understand the differences between the two. 

What is Anti-Static Foam?

Anti-static (ESD) foams help dissipate electro-static charges, which can easily damage sensitive electronic devices and parts. These types of foam have a surface resistance that measures between 109 – 1012 ohms and are made from a static dissipative polyurethane and polyethylene material.  

Their pink coloring makes most ESD foams easy to identify. ESD foams are chemically treated with anti-static agents that allow them to not generate static charges.  They prevent static from being built up by the friction of the item rubbing up against them while in motion. However, they will allow static charges to pass through them. When using this foam in shipping to fully protect static-sensitive devices, make sure the item is placed in a silver conducive bag that will shield it from outside electrostatic charges.

Generally speaking, anti-static foam is not reusable. 

Static Dissipative Foam

Static dissipative foam is a type of foam that allows for static charges to flow to the ground more slowly than conductive materials. Controlling the speed in which charges go to the ground, helps the foam protect the material encased inside of it. This type of foam is generally either carbon-impregnated and colored black or surface treated and colored pink. Static dissipative foam has a low (or no) initial charge and prevents discharges to or from human contact. These types of foam have 105 to 109 ohms.. 

What is Conductive Foam?

Conductive foam is a type of polyethylene foam that is filled with carbon. It is generally identifiable by its black coloring and has a surface resistance of less than 106 ohms. Conductive foam protects electronic devices and components by acting as a Faraday cage, which blocks electromagnetic fields from reaching whatever it is surrounding. This type of foam makes it not necessary to place the item in something that will shield it from outside electrostatic charges. Conductive foam is known to drain batteries if their conductive ends come in contact with the foam. Be sure to shield batteries from the foam if you are using this type of foam to ship or store electronic devices by using a layer of insulation or another type of static dissipative foam.