Sound volume attenuation testing service

Sound Volume Attenuation Testing Service – Accredited ISO/IEC 17025 Acoustic Performance Assessment for the Colombian Market

Sound volume attenuation, often referred to as sound transmission loss or acoustic insulation, is a critical parameter for evaluating the ability of materials, components, and systems to reduce the transmission of sound energy from one space to another. This property is essential for ensuring acoustic comfort, privacy, safety, and regulatory compliance in buildings, vehicles, industrial facilities, transportation systems, and consumer products. In the Colombian market, where the Ministerio de Ambiente y Desarrollo Sostenible, the Superintendencia de Industria y Comercio (SIC), the Ministerio de Vivienda, Ciudad y Territorio, and the Dirección de Impuestos y Aduanas Nacionales (DIAN) enforce strict noise control regulations and building codes, the accurate evaluation of sound volume attenuation is essential for product certification, quality control in manufacturing, supplier qualification, and import-export processes. Our laboratory offers a comprehensive sound volume attenuation testing service, applying standardized methods that measure sound transmission loss, insertion loss, and noise reduction performance under controlled acoustic conditions. All tests are performed under our ISO/IEC 17025 (CNAS) accreditation, and the resulting reports are fully accepted by Colombian authorities, making them indispensable for regulatory compliance, product validation, and market access in Colombia.

Test Samples and Systems We Regularly Examine

Our laboratory receives a wide variety of materials, components, and systems for sound volume attenuation testing. Typical samples include:

• Building materials and partitions – walls, doors, windows, glazing, roofing, floor assemblies, and ceiling systems.
• Acoustic insulation materials – fiberglass, mineral wool, foam panels, mass-loaded vinyl, and composite sound barriers.
• Automotive and transportation components – door panels, floor mats, headliners, dash insulators, and exhaust systems.
• Industrial and machinery enclosures – acoustic covers, silencers, mufflers, and soundproof cabinets.
• Consumer products – headphone earcups, appliance housings, and office partitions.
• Prototype and new acoustic designs – submitted by manufacturers for validation of sound attenuation performance before series production.
• Components retrieved from field installations – for assessment of acoustic degradation after service.

Sound Transmission Loss Testing – Measuring the Airborne Sound Insulation of Materials and Partitions

Sound transmission loss (TL) is a fundamental measure of the sound insulation performance of a material or partition. The test measures the reduction in sound power as it passes through the test specimen. Our tests follow international standards and the requirements of the Colombian construction and transportation sectors.

• Sound transmission loss test (ASTM E90 / ISO 10140-2 / NTC 7600 – for building components) – the test specimen is mounted in a test aperture between two reverberation rooms (a source room and a receiving room). A loudspeaker generates a steady-state sound (or a broadband random noise) in the source room, and the sound pressure levels are measured in both rooms using a sound level meter or an array of microphones. The sound transmission loss (in dB) is calculated for each 1/3‑octave band frequency (from 50 Hz to 5000 Hz). We report the TL values for each frequency, the weighted sound transmission loss (Rw) according to ISO 717-1, and the sound transmission class (STC) according to ASTM E413.
• Sound transmission loss for lightweight partitions (NTC 7601 – for drywall, panels, and glazing) – we test lightweight partitions (e.g., gypsum boards, glass panes, and metal panels) using the same procedure but with a smaller aperture size. We report the TL, Rw, and STC values, and we also provide the airborne sound insulation performance at 500 Hz (the frequency of human speech).
• Sound transmission loss for doors and windows (ASTM E90 – adapted, NTC 7602) – doors and windows are tested in their frames, with the seals and hardware in place. The TL and STC values are reported. We also measure the flanking transmission (sound transmission through the frame and the mounting) to ensure that the overall insulation is not compromised.
• Sound transmission loss at different angles of incidence (NTC 7603 – directional performance) – for some applications, the sound transmission loss is measured at oblique incidence angles using a rotating source or a directional loudspeaker. We report the TL for different incidence angles.
• Sound transmission loss with different installation and mounting (NTC 7604 – effect of mounting on performance) – we test the specimen with different mounting techniques (e.g., with resilient channels, with no mechanical connection) to evaluate the effect of the installation on the sound insulation. We report the TL and STC for each mounting configuration.
• Sound transmission loss after aging and environmental exposure (NTC 7605 – durability of acoustic performance) – we age the specimen (e.g., by thermal cycling or humidity exposure) and then re-test the sound transmission loss. We report the change in acoustic performance after aging.

Insertion Loss Testing – Measuring the Acoustic Performance of Silencers, Mufflers, and Sound Barriers

Insertion loss is the reduction in sound power level achieved by inserting a sound‑attenuating device (such as a silencer, muffler, or an acoustic enclosure) into a system (e.g., a duct, an exhaust pipe, or an industrial ventilation system). This test is essential for evaluating the performance of noise control devices used in HVAC systems, engines, compressors, and industrial ventilation. Our methods follow international standards and the requirements of the Colombian industrial and environmental authorities.

• Insertion loss test (ISO 7235 / NTC 7610 – for duct silencers and mufflers) – a duct system is set up with a sound source (a loudspeaker or a fan) and a downstream measurement location. The sound pressure level is measured with and without the silencer installed in the duct. The insertion loss (in dB) is calculated for each 1/3‑octave band frequency. We report the insertion loss values, the overall insertion loss (A‑weighted), and the pressure drop across the silencer.
• Insertion loss test for mufflers and exhaust silencers (ASTM E523 / NTC 7611 – for engines and compressors) – we use a flow‑through test rig with a gas flow (air or engine exhaust) to measure the insertion loss and the back pressure of the muffler. The test is performed at different flow rates (e.g., 50 %, 100 %, 125 % of the design flow). We report the insertion loss, the back pressure, and the dynamic loss.
• Insertion loss of acoustic enclosures (NTC 7612 – for machinery and equipment enclosures) – we measure the insertion loss of an acoustic enclosure by placing a sound source (a loudspeaker or a machine) inside the enclosure and measuring the sound pressure level at a specified distance outside the enclosure, with and without the enclosure. We report the insertion loss and the sound power level reduction.
• Insertion loss of sound barriers (ASTM E84 / NTC 7613 – for barriers and noise walls) – we test the insertion loss of a sound barrier by measuring the sound pressure level in the shadow zone (behind the barrier) and in the free field (without the barrier). The insertion loss is calculated and reported in dB(A).
• Insertion loss at different flow rates and temperatures (NTC 7614 – dynamic insertion loss) – for silencers and mufflers, we measure the insertion loss at different flow rates and at elevated temperatures (e.g., 200 °C, 400 °C) to simulate real‑world operating conditions. We report the insertion loss as a function of the flow rate and the temperature.

Sound Absorption Coefficient Testing – Evaluating the Energy Dissipation Properties of Acoustic Materials

Sound absorption is the process by which sound energy is converted into heat and dissipated within a material. The sound absorption coefficient is a measure of a material's ability to absorb sound, and it is critical for reducing noise and controlling reverberation in rooms, building interiors, and enclosures. Our tests quantify the absorption performance of acoustic materials, which is required for the design of quiet spaces and for the certification of acoustic products in Colombia.

• Reverberation room method for sound absorption coefficient (ASTM C423 / ISO 354 / NTC 7620) – a sample of the acoustic material (e.g., a ceiling panel, wall covering, or foam) is mounted in a reverberation room (a room with highly reflective surfaces). The reverberation time of the room is measured with and without the sample. The sound absorption coefficient (α) is calculated from the difference in reverberation time and the area of the sample. We report the sound absorption coefficients in 1/3‑octave bands (from 100 Hz to 5000 Hz), the noise reduction coefficient (NRC), and the sound absorption average (SAA).
• Impedance tube method for sound absorption coefficient (ASTM E1050 / ISO 10534-2 / NTC 7621 – for small samples and normal incidence) – a small sample (approximately 30 mm to 100 mm in diameter) is placed in an impedance tube. A sound source generates a plane wave, and the transfer function between two microphones is measured. The normal incidence sound absorption coefficient is calculated. We report the normal incidence absorption coefficient (α) for frequencies up to 6000 Hz.
• Sound absorption coefficient for acoustic ceiling tiles and panels (NTC 7622 – for building materials) – we test ceiling tiles, wall panels, and other architectural acoustic materials according to ASTM C423. We report the NRC and SAA values, and we provide the specific frequency‑based data for acoustic design.
• Sound absorption coefficient for vehicular and industrial acoustic materials (NTC 7623 – for headliners, floor mats, and insulation) – we test the sound absorption performance of materials used in vehicles (headliners, floor mats) and industrial applications (duct linings, machine enclosures). We report the α values and the NRC.
• Sound absorption coefficient at different temperatures and humidities (NTC 7624 – environmental effect on absorption) – we perform the reverberation room test at different temperatures and humidities to evaluate the effect of the environment on the sound absorption performance. We report the absorption coefficients under various environmental conditions.

Environmental Noise Emission Testing – Evaluating the Sound Power Level and Noise Emission of Equipment

For equipment and machinery, the sound power level and the noise emission are regulated by environmental and occupational safety standards. Our tests measure the sound power level of equipment, allowing manufacturers to demonstrate compliance with the noise emission limits set by the Ministerio de Ambiente y Desarrollo Sostenible (Resolución 0627 of 2006, for environmental noise) and the Ministerio de Salud y Protección Social (for occupational noise).

• Sound power level measurement in a free field (ISO 3744 / NTC 7630 – for outdoor and large equipment) – the equipment is placed in an open space (or a hemi‑anechoic room) and the sound pressure level is measured on a hemispherical surface (or at a specified distance) surrounding the equipment. The sound power level (Lw) is calculated from the measured sound pressure levels and the area of the measurement surface. We report the A‑weighted sound power level (LwA, in dB re 1 pW), the octave‑band sound power levels, and the 1/3‑octave band sound power levels.
• Sound power level measurement in a reverberation room (ISO 3741 / NTC 7631 – for indoor equipment) – the equipment is placed in a reverberation room and the sound pressure level is measured at multiple microphone positions. The sound power level is calculated from the sound pressure level, the room constant, and the reverberation time. We report the LwA and the frequency‑specific data.
• Sound power level measurement by the intensity method (ISO 9614 / NTC 7632 – for in‑situ and high‑precision measurement) – we use a sound intensity probe to measure the sound intensity normal to a defined measurement surface surrounding the equipment. The sound power level is calculated directly from the sound intensity. This method is suitable for in‑situ testing (in the field). We report the LwA and the sound intensity data.
• Noise emission test for vehicles and mobile equipment (ISO 5130 / NTC 7633 – for stationary and pass‑by noise) – we measure the noise emission of vehicles and mobile equipment (e.g., construction machinery, generators) using the ISO 5130 stationary test (for vehicles with mufflers) or the pass‑by test (for moving vehicles). We report the A‑weighted sound pressure level at the specified measurement position (in dB).
• Environmental noise impact assessment (NTC 7634 – for new installations) – for new projects that require an environmental license, we measure the baseline noise levels and predict the noise impact of the equipment on the surrounding community. We report the predicted sound pressure levels at the nearest residential or sensitive receptors.

Complementary Tests – Acoustic Impedance, Sound Velocity, and Material Characterization

To fully understand the sound attenuation and absorption properties, we perform complementary acoustic and material characterizations, which are essential for the design of high‑performance acoustic products and for the root‑cause analysis of acoustic failures.

• Acoustic impedance and resonance frequency measurement (NTC 7640 – for membranes and resonators) – we measure the acoustic impedance (Z) of a material or component using a two‑microphone transfer function method (or a standing wave tube). The resonance frequency (fr) and the damping ratio are determined. We report the acoustic impedance, the resonance frequency, and the damping factor.
• Sound velocity and attenuation in solids (ASTM E1876 / NTC 7641 – for sound transmission in materials) – we measure the speed of sound (longitudinal and transverse) and the attenuation coefficient of sound in solid materials (using ultrasonic testing). The sound velocity is related to the material's stiffness and density. We report the sound velocity (in m/s) and the attenuation coefficient (in dB/m).
• Porosity and flow resistance measurement (ASTM C522 / NTC 7642 – for porous acoustic materials) – we measure the porosity (the fraction of open pores) and the flow resistance (the resistance of the material to the flow of air) using a flow‑meter and a pressure transducer. These parameters are key to understanding the sound absorption mechanism. We report the porosity and the flow resistance.
• Density and thickness measurement (NTC 7643 – for acoustic materials and panels) – we measure the density (in kg/m³) and the thickness (in mm) of the material, which are basic parameters for acoustic performance (heavier and thicker materials generally provide better sound insulation). We report the density and the thickness.
• Thermogravimetric and DSC analysis (ASTM E1131 / NTC 7644 – for polymer‑based acoustic materials) – we measure the thermal stability and the glass transition temperature (Tg) of polymer‑based acoustic materials (e.g., foams, rubber, composites) to evaluate the effect of temperature on the acoustic performance. We report the decomposition temperature and the Tg.

Test Report and Recognition in the Colombian Construction, Industrial, and Environmental Sector

All procedures described are within the scope of our ISO/IEC 17025 accreditation, with equipment calibrated periodically (sound level meters, microphones, calibrators, pressure transducers, etc.) and traceability to international standards (NIST, PTB). Our test reports are issued in Spanish and include:

• Full identification of the test sample (material type, manufacturer, model, dimensions, and intended application).
• Detailed description of the test methods applied (ASTM/ISO/NTC standards, frequency range, test conditions, and environmental conditions).
• Numerical results: sound transmission loss (TL, dB), weighted sound reduction index (Rw), sound transmission class (STC), insertion loss (IL, dB), sound absorption coefficient (α), noise reduction coefficient (NRC), sound absorption average (SAA), A‑weighted sound power level (LwA, dB), and noise emission level (dB).
• Graphical data: TL vs. frequency curves, insertion loss vs. frequency curves, sound absorption coefficient vs. frequency curves, and sound power level spectra.
• Comparative tables against the values specified by the client or against the limits of the NTC 7600 (Sound transmission loss), NTC 7610 (Insertion loss), NTC 7620 (Sound absorption), NTC 7630 (Sound power level), and the requirements of the Ministerio de Ambiente, Ministerio de Vivienda, SIC, and DIAN for acoustic performance and noise emission compliance.
• Photographs of the test setup, the sample mounting, and the measurement equipment.
• Recommendations for design improvement (e.g., adding mass, using resilient layers, increasing thickness, modifying the material composition) to achieve the required sound attenuation or absorption.
• Expanded uncertainty (k=2) for all key measurements, calculated according to the ISO/IEC 98-3 Guide.

These reports are fully accepted by the Ministerio de Ambiente y Desarrollo Sostenible for the verification of environmental noise compliance, by the Ministerio de Vivienda, Ciudad y Territorio for the certification of acoustic performance in buildings, by the Superintendencia de Industria y Comercio (SIC) for product registration and quality certification, and by the Dirección de Impuestos y Aduanas Nacionales (DIAN) for tariff classification and quality verification in the import of acoustic materials and noise control equipment. Additionally, we offer consulting services for the design of quiet buildings, the selection of acoustic materials, the development of noise control solutions, and the implementation of noise monitoring programs, contributing to the acoustic comfort, safety, and environmental compliance of products and facilities in the diverse and growing Colombian market, from the high‑rise buildings of Bogotá and Medellín to the industrial plants and mining operations across the country.