How to address mid-to-high frequency issues?

1. Core Principle: Control Logic for Medium and High-Frequency Noise
Medium and high-frequency sound waves have shorter wavelengths, weaker diffraction capabilities, and are easily absorbed by porous materials or reflected/blocked by dense structures. Therefore, solutions  around two core aspects:
Sound absorption: Using porous materials to dissipate sound wave energy, reducing reflection and reverberation.
Sound insulation: Using dense, massy structures or damping materials to block the path of sound wave transmission.  

systems, and the solution is mainly based on a combination of sound absorption and insulation:
Sound absorption treatment
Choose porous materials with excellent mid to high frequency sound absorption performance, such as polyester fiber sound-absorbing cotton (density 30-50kg/m ³ is optimal), glass wool (centrifugal glass wool board, thickness ≥ 50mm), and rock wool board. The pore structure of these materials can efficiently capture mid to high frequency sound waves.
Construction points: Materials should be installed exposed (avoiding covering dense films), and can be made into sound-absorbing ceilings, sound-absorbing wall panels, or sound-absorbing barriers can be set up around noise sources.
Advanced solution: Adopting a composite structure of perforated panels and sound-absorbing cotton (perforation rate of 20% -30%), the perforated panels reflect sound waves, and the sound-absorbing cotton absorbs the penetrating mid to high frequency energy, suitable for high demand control rooms and laboratories.
Sound insulation treatment
Door and window optimization: Replace double-layer insulated glass (glass thickness difference ≥ 3mm, hollow layer ≥ 12mm), install soundproof tape (butyl rubber material, good sealing) at the door gap, and block the propagation of sound waves through the gap.
Wall reinforcement: Install a composite structure of gypsum board and damping layer (such as damping sound insulation felt) on the original wall. The damping layer can suppress the vibration of the board caused by mid to high frequency sound waves and improve the sound insulation effect.

2. High frequency noise control in industrial equipment (fans, motors, compressors)
The device itself is a medium to high frequency noise source, and it needs to start with source noise reduction and propagation path blocking:
Source noise reduction
Equipment installation of mufflers: Resistive mufflers (filled with sound-absorbing cotton) are installed at the exhaust ports of fans and pipelines. Resistive mufflers can reduce medium to high frequency noise by 10-30dB (A), making them the preferred choice for industrial equipment.
Vibration isolation: Rubber damping pads or spring dampers are installed between the equipment and the foundation to reduce secondary high-frequency noise caused by vibration transmission.
Blockage of transmission path
Equipment installation of soundproof cover: The soundproof cover shell is made of steel/aluminum plate, with sound-absorbing cotton and perforated protective surface pasted on the inner wall. A ventilation space is reserved between the cover body and the equipment to avoid heat dissipation problems. At the same time, the joint is sealed with soundproof tape, which can reduce medium and high frequency noise by 20-40dB (A).

3. High frequency noise control in mobile scenarios such as automobiles and rail transit
The mid to high frequency noise in this type of scenario comes from engine, tire, and wind noise, and needs to be combined with material lightweight and efficient sound absorption and insulation design:
Interior sound absorption: Fill the interior panels of the car doors, roof, and trunk with polyurethane sound-absorbing cotton (flame retardant type) to absorb high-frequency reverberation inside the car; Install damping and sound insulation panels on the chassis to suppress the mid to high frequency noise generated by sheet metal vibration.
Tire noise control: Stick butyl rubber soundproof tape on the inner wall of the tire to reduce the mid to high frequency noise caused by tire tread vibration; The wheel hub cover is covered with porous sound-absorbing material.

3、 Key Material Selection Table (for Medium and High Frequency)




Regarding solutions for medium and high-frequency issues at Foshan Zhiwei Adhesive Products Co., Ltd., we welcome inquiries from major manufacturers. Please contact us at yang@fszw-tapes.com