The influencing factors of the sound absorption performance of foam rubber
Foam rubber board exhibits excellent sound absorption capabilities. However, during practical application, several factors significantly influence its performance, such as thickness, density, and airflow resistance.
Airflow resistance refers to the ratio of air pressure difference to airflow velocity across a unit thickness of material. It critically impacts the sound absorption efficiency of foam rubber insulation board. If the airflow resistance is too low, it indicates the material structure is sparse, allowing noise to easily penetrate during sound propagation, resulting in diminished performance.
1. Physical Structure & Environmental Factors:
The sound absorption performance is directly related to its inherent physical structure. Featuring a tight closed-cell foam structure with an elastic surface, this material effectively mitigates external noise. However, environmental factors during actual use determine its sound isolation and reduction effectiveness. Thickness, density, and airflow resistance exert substantial influence on noise reduction.
2. Application Example & Key Principle:
Consider egg crate foam rubber board, often used for soundproofing drain pipes. For effective performance, manufacturers recommend using thicker, adhesive-backed panels. A critical principle is: To maximize noise reduction, the textured (corrugated) surface must face the sound source. The peaks and valleys, combined with dense open-cell structures, refract sound waves to reduce noise. As noise is harmful, foam rubber board serves as vital material for confining sound pressure within safe thresholds.
3. Impact of Thickness & Weight:
Increasing thickness gradually enhances sound absorption coefficients in mid-to-low frequencies, while high-frequency absorption remains largely unaffected. Increasing overall weight similarly improves low-mid frequency absorption. Beyond a certain density threshold where the structure becomes tighter, overall absorption efficiency progressively increases.
4. Effect of Bulk Density:
Sound absorption coefficients directly correlate with bulk density. Paradoxically, higher bulk density may reduce sound absorption performance as excessive compaction diminishes acoustic energy conversion capability.
