Insulating your product design with better sound dissipation can enhance its desirability.

By Carrie Ellis, Editor

Thinsulate™ is used by appliance manufacturers for quiet operation.

According to 3M Acoustic Solutions Product Development Specialist Jon Alexander, "Today’s consumers want appliances and office products that are not only reliable, energy efficient, and well built; they want them to be q-u-i-e-t ... Recent developments have given design engineers greater flexibility in sound management, while reducing part size and weight."

However, he admits, the most difficult thing about acoustics is that although most designers know what it can add to the desirability of a product design, it's difficult to quantify. While some acoustics can help positively differentiate a product from the competition, it can also be perceived as a negative characteristic. Alexander believes that with technology such as voice-activated products growing in popularity, noise may emerge an even more critical issue if it interferes with the performance or perception of a product.

All About What Your Customer Wants

Low noise levels are often a sign of quality, but preferred noise levels differ not only by culture, but also by function. Americans tend to favor vacuums and off-road motors that make a certain amount of noise to ensure proper and consistent operation, not to mention the capacity for power output. In contrast, one feature that characterizes a Lexus as a high-status vehicle is its propensity for being quiet.

Some cultures opt for visual assurance of proper operation of a product, like a light indicating that the vacuum is functioning. In other cultures, the noise a product makes can be more reassuring. As far as regulations go, Europe is far more stringent than the U.S. in regard to industrial noise control requirements. In conclusion, what may be noisy to one culture isn't necessarily noisy to another.

Many studies, some of which include jury testing and demographic difference studies, have been conducted on the topic of the effects of noise in relation to product desirability. These small factors can enormously impact the consumer's perception of a product. When designing a new product, here are some different aspects of noise you may want to consider: the actual level of noise as it relates to general standards, the demographic's comfort level and expectations with noise, and noise feedback.

Design engineers must not only worry about what to use as an acoustic absorber, but must also consider its thickness and size pertaining to surface area. You must also evaluate the optimal placement for that absorber, which entails first searching for and locating the pathways of sound in a product, determining whether the result of using a sound absorber would be worth the process and figuring how to best place the absorber to be most effective. But then you must decide how to attach it, which includes considering manufacturing clearances and tolerances of the material used.

Where To Start

Alexander says other items to consider during the materials selection process are:

• Weight and compressibility.
• Hydrophobic--or a material's propensity to absorb water.
• Effects on other features, such as efficiency or size.
• Ease of use, along with handling, cutting and attachment options.
• Cost effectiveness when installed.

Alexander suggests, when choosing the practicality of using a particular sound absorber, you also delineate what the company is looking for in terms of noise levels. Or more specifically, ask yourself: What value would sound absorption bring to the product, and essentially the end-user?

Alexander says one of the first instances he can think of that designers built acoustic dissipation into their design plans for structural purposes--breaking the sound  barrier--was about 50 years ago. Breaking the sound barrier is so loud that it can literally disrupt the security of the aircraft's infrastructure. As a result, engineers began to manufacture a special fiberglass to absorb the impact better, first with military, and soon thereafter, commercial aircraft.

The Options

The materials used for absorbing sound have progressed slowly and steadily over the years. Alexander says, "Appliance manufacturers have traditionally relied on a variety of nonwoven acoustic insulation materials, including fiberglass, material remnants (shoddy, needled felt, fibrous material) and various synthetic insulation materials. Traditional sound absorbers, however, can present challenges, such as issues of weight, effectiveness, conformability, handling and moisture resistance, among other factors. Today's advanced insulations, based on new synthetic materials, manufacturing processes and structures, address many of these issues through improved performance and enhanced material properties."

This is, of course, not to say that traditional sound absorbers don't have a place in the noise dissipation market. It simply boils down to the issue of what makes a product more or less desirable in a certain application in the given target market within certain cost restraints.

According to Alexander, "Noise always finds the path of least resistance, much like water always finds somewhere to flow," which is why 3M's new acoustic noise dissipation solution is a low-density, cavity-filling absorber--to better capture acoustic energy, and therefore dissipate it, rather than deflecting it. Called Thinsulate™ acoustic insulation, this absorber is made up of advanced nonwoven materials that are "highly efficient because they allow sound waves to enter easily, and then force the sound waves to flow over a large amount of fiber surface, which then dissipates the energy in the form of thermal energy."

He continues, "Thinsulate, for example, has a high-noise reduction coefficient ratio by weight and thickness. The synthetic material is also naturally hydrophobic to resist mold and mildew, and highly conformable, allowing it to be engineered into areas previously off-limits. Thinsulate is manufactured using a process that produces ultra-fine synthetic fibers. A combination of fine and large fibers provide more surface space for the sound waves to flow over and loft, resulting in superior sound absorption in a low density product. Together, they allow the insulation to compress and recover easily, offering design flexibility."

Other suggestions Alexander makes when deciding what kind of material to use are: choose finer or more unified materials for difficult sound dissipation, and modeling the noise solution in the virtual world before physical testing. As always, the application with which you are working is the single largest factor in any purchasing decision.

To learn more about 3M Acoustic Solutions or for further assistance with noise issues, visit Thinsulate.com.