Product Announcement from Accurate Perforating & Metal Fabricating
Accurate is the leading manufacturer of perforated components for the noise control and loudspeaker industries. Our material is used extensively to control sound and protect acoustical media. We perforate and fabricate metal for speaker grilles, ceiling tiles, wall panels, enclosures, highway barriers, industrial silencers, HVAC systems, and many more applications.
Perforated metal is formed and installed in many places to aid in noise abatement - swimming pools, gyms, concert halls, even subways benefit from our collaboration with acoustical designers.
Perforated metal is used as a protective or decorative covering for some special acoustical material; that material may be designed either to absorb sound or to reflect or scatter sound in a special way. So, the purpose of the perforated metal in such applications is to be so "transparent" that the sound waves pass right through it, without being diminished or reflected, to encounter the acoustical treatment that lies behind.
In many noise control applications, the objective is to remove or reduce sounds that occur only in a narrow range of frequencies. For such situations it is possible to design a sound absorptions system that is "tuned" to those targeted frequencies in which perforated metal plays a critically active role. This kind of system is called a Tuned Resonant Absorber. By employing such a system, the designer can reduce the thickness of the absorbing layer and save space and cost.
In a resonant sound absorber, the air motion in and out of the holes in the perforated metal sheet oscillates in response to an incident sound wave. The preferred frequency of oscillation is determined by the mass of the air in the perforations and the springness of the trapped air layer. At that frequency, the air moves violently in and out of the holes and, also, back and forth in the sound absorptive layer where the acoustic energy in converted by friction into heat and is thereby removed from the acoustical scene. It is the interaction between the thickness of the perforated sheet and the size and number of the holes in it with the depth of the trapped air layer, that determines the target frequency and thereby the thickness of the absorbing layer required to remove the sound.
As a component of a resonant sound absorbing system, perforated metals provide unique capabilities.