Controlling how and when sounds are absorbed is pivotal for equipment and machinery. Acoustic designers use a combination of tactics and materials to control sound absorption and direction. One method manufacturers use is adding layers of composite materials, foams, and films to create panels with different rates of absorption.
Micro perf, or micro perforation, is a film with tiny holes. Manufacturers apply this perforated film to acoustic foams to help absorb noise. Ideally, this addition should make the acoustic foams and composites absorb sounds at lower Hertz levels without adding mass or weight to the foam. However, an internal study found this was not the case, as micro perforated materials that were tested alongside unperforated materials provided minimal distinctions in sound absorption.
What Is the Proposed Advantage?
Acoustic designers routinely look for ways to smooth out sounds without bulking up acoustic foams. Micro perf’s intended job is to help tune lower frequencies without impacting high-end frequency absorption. At Technicon we sought to determine if the perforated films were able to tune, or if they simply reduced the structural integrity of the film.
What Is the Result?
Tests of normal incidence absorption comparing unperforated films with micro perf materials indicated little to no signs of effectiveness. Perforated material did not change absorption across the frequency spectrum. While the tests indicated some marginal changes, the changes would not alter the sound experience. Listeners would not be able to perceive audible differences.
During tests with random incidence absorption compared to micro perfs, testers found some material effects. Microperf created smoother sound absorption effects. But the cost of this modification was an overall higher frequency of sound. Unperforated material in the same random incidence environment led to similar results.
Another limitation of micro perf is its porosity. Covering acoustic foam with nonporous films — with no perforations —has several benefits, such as preventing oils and moisture from contaminating the foam. But the holes make micro perf porous.
In fact, the tests seem to indicate, micro perf just creates an additional expense with no added value, since micro perf is more expensive than non-perforated alternatives. The holes also allow substances like water, oil, and grease to damage the material. Perforations can also shorten the lifespan of acoustic foams by allowing UV radiation to degrade the material.
Contact Technicon Acoustics for More Sound Science Help
There’s no short cut to fixing absorption peaks and smoothing out sound. Instead, professionals need to be able to tune acoustic absorbers and find the right ratios between the foam’s composite layers.
Technicon Acoustics specializes in creating acoustic solutions that improve sound quality. Our products are designed to absorb, block, or isolate high- or low-frequency sounds. We have a team of expert sound engineers and scientists that research, design, and test high-quality sound shielding equipment.
You can order standard shielding and damping equipment or talk to our team about a customized solution just for your facility’s needs. We work hard to create the perfect order experience. This includes shipping the correct quantities and types of material on time for every order so our customers can confidently move forward with complex or time-sensitive projects.