Sound Transmission loss Tester

Background
The demand for efficient and sustainable acoustic materials is increasing rapidly across industries such as construction, automotive, aerospace, and textiles. A critical performance metric for these materials is Sound Transmission Loss (STL), which quantifies their ability to block sound. Accurate STL evaluation is essential for developing noise-reducing materials and ensuring compliance with acoustic standards in real-world applications.
Conventional STL testing methods include the reverberation chamber and impedance tube techniques are often impractical for routine testing due to their high cost, space requirements, and large sample sizes. To enable preliminary understanding of sound transmission across materials, a compact, indigenous Sound Transmission Loss Tester has been developed. It offers a cost-effective, accurate, and repeatable method to evaluate STL using smaller material samples (10x10 cm to 20×20 cm). Designed to comply with standard testing methodologies (e.g. ASTM E90), this system is ideal for sheet materials such as: Textiles and nonwovens, bio-composites, Glass, wood, and fiberboards
This innovation enhances R&D capabilities in eco-friendly acoustic solutions, especially in validating coarse wool-based panels and other sustainable materials. It is an affordable and scalable solution for acoustic testing without the need for high-end infrastructure.
Technology Details
Sample Size Compatibility: 10 x 10 cm or to 20 x 20 cm
Material Compatibility: Nonwoven and woven textiles, Coarse wool-based composites, Wood, glass, fibreboard, biopolymers, metal, plastic, rubbers
Frequency Range of Sound Source: 50 Hz to 20,000 Hz-adjustable according needs
Sound Source Types: Synthetic noise generators (white, pink, or sine sweeps), Real-world sound sources (e.g., voice, angle grinders, mixers)
Measurement Components:
Sound Level Meter (SLM) for calibrated dB readings
Computer with calibrated microphone interface for digital data acquisition
- Simplified two-chamber setup with sealed sample holder
Calibration & Accuracy:
- Easy microphone and background noise calibration

Stable readings across frequencies
Minimizes internal reverberation for improved measurement precision
Data Output: STL values (in dB) and frequency (Hz)
Unique Features & Advantages
Compact, portable design requires minimal space and supports easy relocation.
User-friendly operation with simple calibration and quick testing process.
Affordable alternative to bulky reverberation chambers and costly impedance tubes.
Modular construction allows easy maintenance and future upgrades.
Complies with ASTM E90 standards for reliable testing.
Supports sustainable innovation by testing natural fiber composites like coarse wool.
Uses small test specimens, making testing economical and convenient.
Minimizes internal reverberation, ensuring accurate and repeatable measurements.