1.Basic Parameters of Sound Barriers

A sound barrier is an acoustic shielding device placed between a sound source and a receiving point. It reduces noise propagation by reflecting, absorbing, and diffracting sound waves. The core performance parameters of a sound barrier include:

(1)Noise Reduction Effect:

Average Sound Insulation: Typically between 25 and 40 dB(A), with the specific value depending on the material and structure. For example, metal sound barriers can achieve 30-42 dB, while concrete barriers are approximately 30-38 dB.

Sound Absorption Coefficient: Recommended value ≥ 0.6; high-quality sound-absorbing materials can achieve 0.8-0.98, such as aluminum foam and superfine glass wool.

Noise Reduction Frequency Characteristics: Significantly effective for mid-to-high frequency noise (above 2000 Hz), reducing noise by 10-15 dB, but less effective for low-frequency noise (<250 Hz).

Effective Height: Typically 2.5~5m. For every doubling of height, noise reduction increases by approximately 6dB. Heights exceeding 6m require optimization using folded panels or enclosed structures.

(2)Structural Parameters:

Panel Thickness: Common specifications are 50mm or 100mm, but custom designs are also available.

Column Spacing: Generally 2000mm, but needs adjustment based on wind load and height.

Sound Insulation and Absorption Requirements: Weighted sound insulation + traffic noise spectral correction ≥ 26dB (A). The recommended noise reduction coefficient (NRC) for roadside sound-absorbing panels is ≥ 0.6.

(3)Durability:

Weather Resistance: Must possess UV resistance, high and low temperature resistance (e.g., -40℃~80℃), and corrosion resistance (salt spray test ≥ 1000 hours).

Fire Rating: Must achieve Class A flame retardancy, such as with metal composite panels or fiberglass materials.

2.Main Materials of Sound Barriers

Sound barrier materials can be categorized by function into sound-absorbing, sound-insulating, and composite types. Commonly used materials include:

(1)Metallic Materials:

Types: Galvanized steel sheet, aluminum sheet, color steel sheet, stainless steel sheet, etc.

Features: Lightweight, easy to process; filling with ultra-fine glass wool or rock wool (density 48kg/m³) can enhance sound absorption; the surface can be treated with electrostatic spraying for weather resistance and corrosion protection; colors are optional.

Sound-absorbing structures: Commonly used are louvered perforated types, micro-perforated panels, etc., with a noise reduction coefficient NRC≥0.85.

(2)Transparent Materials:

Types: PC endurance board, laminated glass, acrylic sheet, polycarbonate sheet, etc.

Features: Good light transmission, suitable for landscape areas; sound insulation 30~40dB(A); impact resistant and weather resistant.

Non-metallic Materials:

Concrete: Lightweight or high-strength concrete; low cost but heavy, requiring a reinforced foundation.

Fiberglass: Glass fiber reinforced plastic with built-in sound-absorbing cotton, fireproof and corrosion-resistant, weighted sound insulation of 30~38dB.

Aluminum Foam: Porous metal sound-absorbing material, fireproof, moisture-proof, with a lifespan of up to 20 years, and excellent high-frequency sound absorption performance. An example is its application on the Shanghai Lupu Bridge.

3.Types of Sound Barriers (Classified by Material and Structural Form)

Sound barriers can be classified into the following categories based on material, structure, and application:

(1)Classified by Material:

Metal Sound Barriers: Galvanized steel/aluminum sheet + sound-absorbing filler, economical and efficient, the most common type.

Concrete Sound Barriers: Heavy-duty and durable, suitable for fixed road sections, such as near viaduct piers.

Transparent Sound Barriers: PC board/laminated glass, balancing sound insulation and visual appeal.

Fiberglass/Composite Materials: Lightweight and corrosion-resistant, used in chemical or coastal areas.

(2)Classified by Structural Form:

Vertical Type: Standard vertical panels, low cost but limited noise reduction range.

Folded/Arc-Shaped:A top-bending design (e.g., 30°~60° angle) enhances noise reduction through sound wave reflection, improving noise levels by 3~6dB.

Semi-Enclosed/Fully Enclosed:A top-enclosed structure used in highly sensitive areas, such as near residential areas, achieving noise reduction of over 20dB.

Ecological:Combines green plants (e.g., climbing vines) with sound-absorbing materials, providing both noise reduction and aesthetic appeal.

4.Types of Sound Barriers (Classified by Noise Reduction Principle and Application Scenarios)

(1)Classified by Noise Reduction Principle:

Reflective:Metal or concrete panels directly reflect sound waves, effective for high frequencies.

Sound-Absorbing/Insulating Composite:A combination of sound-absorbing materials (e.g., aluminum foam, glass wool) and sound insulation panels, offering optimal overall performance.

(2)Classified by Application Scenarios:

Transportation:Sound barriers for highways, railways, and subways, 2~5m high, covering noise-sensitive areas.

Industrial:Sound barriers for factories, cooling towers, and generator sets.

Construction: Sound insulation facilities attached to community walls and bridges.