Scientific tests demonstrate that micro-perforated panels (MPPs) display impressive sound absorption properties, but prior to the introduction of SoundPly panels, these properties were rarely observed outside of laboratories.
While developing SoundPly panels, we researched why commercially available micro-perforated panels did not perform to their potential. We identified three primary reasons:
For effective resonate sound absorption to occur, a micro-perforation’s passage must be smooth with clean and sharp edges. These conditions allow air inside the passage to efficiently move en masse, resonating back and forth at thousands of times per second.
Most MPPs are manufactured using a punch perforator machine, which works well with soft materials such as fabric and leather, but not with wood veneer. The punching process crushes veneer, resulting in coarse micro-perforations with fractured passages, which disrupt and restrict the resonating airflow. It’s a process equivalent to using a hammer to remove the core of an apple. It’s one method, but it’s definitely not ideal.
Navy Island has engineered a better process. Using a sequence of broaching pins to create and refine each micro-perforation, Navy Island produces the cleanest, sharpest micro-perforations possible.
The quality of construction matters little if a micro-perforation’s passage is blocked. Tests show that if just 5% of micro-perforations are obstructed, tapered, or have rough walls, a panel’s ability to absorb sound is measurably reduced.
Apart from SoundPly, all MPPs are constructed with bored MDF or PB core, which completely blocks most of the micro-perforations—
Less than 34% of other manufacturers’ micro-perforations are functional.
SoundPly panels are constructed using a process developed specifically to ensure that the micro-perforations are clean and completely unobstructed—
99.97% of SoundPly’s micro-perforations are functional.
There are four principle factors which control the resonate properties of a microperforation:
1. Diameter of the micro-perforations
2. Depth of the micro-perforations
3. Spacing between the micro-perforations
4. Cavity depth behind the micro-perforation
Seeking to improve the acoustic performance of existing MPPs, Navy Island tested numerous micro-perforations displaying variations of these four different dimensions. Through this process, Navy Island was able to “tune” the micro-perforations, achieving the broadest range of sound absorption across the most relevant frequencies. The tests revealed the ideal micro-perforation dimensions: a diameter of .45-.55mm at a depth of 1.8-2.1mm, spaced 2.5mm apart.
Due to manufacturing limitations, other MPPs are produced with micro-perforations no deeper than .9mm, and many with depths shallower than .5mm. During testing, Navy Island measured the performance of micro-perforations with those depths. The differences were measurable. In overall sound absorption, micro-perforations with depths of .9mm and .5mm performed 28% and 45% poorer, compared to a depth of 1.8mm.
Why does a micro-perforation’s depth factor so significantly in improving sound absorption? The deeper the micro-perforation, the more surface area exists to absorb energy from the sound wave. Furthermore, as sound energy increases, deeper micro-perforations allow for a more organized, focused flow of disruptive air movement— a feature of Dynamic Sound Control, detailed more in the next section.