Do you know which method is used to measure the sound absorption coefficient of materials?

We found that many acoustic researchers collect the sound absorption coefficients of materials in experiments, and some architectural design engineers are also very concerned about the sound absorption coefficients of materials. Why is it so important to understand the sound absorption coefficients of materials? Because once people understand the sound absorption coefficients of materials, they can more freely choose and use sound-absorbing materials. In building design and construction, the development and use of environmentally friendly sound-absorbing materials can effectively control and resist noise, reduce noise pollution, and improve the quality of the living environment; in places such as concert halls, theaters, and conference rooms that require specific acoustic characteristics, the reasonable use of sound-absorbing materials will help control the clarity of sound and reverberation time. Based on current laws, regulations, and industry standards in related fields, different measurement methods can be chosen to obtain sound absorption data for materials according to different needs.

Common methods for measuring the sound absorption of materials include the following:

• Reverberation Room Method

The reverberation room method utilizes a room with a uniformly diffused sound field to determine the sound absorption characteristics of materials by measuring the difference in sound energy decay before and after the material is placed. This method simulates the random incidence of sound waves in a real environment, and the measured sound absorption coefficients are relatively close to the actual sound absorption performance during use.

• Impedance Tube Method

The impedance tube method uses the principle of standing waves to calculate the sound absorption coefficient and acoustic impedance of materials by measuring the distribution of reflected and incident sound pressure within the tube. This method is suitable for measurements in the mid to high frequency range and has high testing accuracy.

• Dual Microphone Method

The dual microphone method measures incident and reflected waves simultaneously using two microphones to separate sound wave components, suitable for a wider frequency range, including low frequencies.

• Free Field Method

The free field method measures the sound absorption coefficient of oblique incidence by setting specific angles of incidence in a free or semi-free sound field. It is suitable for measuring the sound absorption performance of large-scale materials or structures, applicable in open environments and outdoor sound-absorbing materials.

• Local Plane Wave Method

The local plane wave method is a unique sound absorption measurement method used by SonoCat multifunctional acoustic measurement equipment. It captures and analyzes sound using a spherical microphone array, decomposing the sound field into incident and reflected parts, allowing for precise measurement of sound absorption. This method provides an innovative in-situ measurement technique for sound absorption coefficients, overcoming the reliance of traditional methods on laboratory environments, making precise sound measurements possible in various real-world environments.

In practical applications, for architectural acoustic design, the reverberation room method may be more suitable; for product development and quality control, the impedance tube method or dual microphone method may be more precise; if considering environmental factors or timeliness, one can try using SonoCat, a professional acoustic measurement device, to obtain the required data on-site.

Here are some experts and architectural design engineers using SONOCAT equipment to measure the sound absorption of materials on-site; let's experience it together: