Method for measuring sound absorption coefficient by virtue of cepstrum

Abstract

The invention discloses a method for measuring a sound absorption coefficient by virtue of a cepstrum. The method comprises the steps: applying a sound absorption material on a rigid wall, arranging a loudspeaker just in just front of the sound absorption material, reflecting a sound wave sent by the loudspeaker by virtue of the sound absorption material so as to obtain sound pressure at a microphone, converting the obtained sound pressure to the cepstrum, and comparing the cepstrum with a cepstrum which is obtained by converting sound pressure measured by the microphone after the sound absorption material is removed to obtain a reflection coefficient of the sound absorption material, so as to obtain the sound absorption coefficient of the sound absorption material. With the adoption of the method, the disadvantages of a conventional standing wave pipe method and a conventional reverberation chamber method for measuring the sound absorption coefficient of the sound absorption material are overcome, and a simple and rapid measuring method is obtained.

Description

technical field [0001] The invention relates to the field of noise, in particular to the measurement of the sound absorption coefficient of sound-absorbing materials, in particular to a cepstrum method for measuring the sound-absorption coefficient of sound-absorbing materials. Background technique [0002] Sound absorption and noise reduction is the use of sound-absorbing materials or sound-absorbing structures to reduce noise. The sound absorption mechanism of sound-absorbing materials is: when a sound wave is incident on the sound-absorbing material, due to the damping effect of the sound-absorbing material, part of the sound wave is absorbed and consumed by the sound-absorbing material, and part of the sound wave is reflected back. Therefore, the sound absorption coefficient is defined as the ratio of the sound energy absorbed by the sound-absorbing material to the sound energy of the incident sound wave. Traditional sound absorption coefficient measurement methods main...

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Problems solved by technology

However, there are some shortcomings in measuring the sound absorption coefficient of sound-absorbing materials with the standing wave tube method, mainly as follows: 1. Errors will be caused when the probe searches for the maximum and minimum values ​​of the sound pressure; 2. The sound absorption of the sound-absorbing material cannot be obtained immediately 3. The measurement of the sound absorption coefficient of loose materials such as sand is powerless; 4. The size of the sound-absorbing material sample must be precisely matched with the size of the standing wave tube, otherwise it will cause a large error

The principle of measuring the sound absorption coefficient of the sound-absorbing material by the reverberation chamber method is to obtain the sound absorption coefficient of the sound-absorbing material by measuring the reverberation time, but there are some shortcomings in measuring the sound absorption coefficient of the sound-absorbing material by the reverberation chamber method, mainly There are: 1. The measured value of the sound absorption coefficient of the same material in each reverberation chamber is sometimes very different, so that the measurement results are not comparable; 2. The size of the sound absorption coefficient varies with the change of the material area and its indoor position. change, and the sound absorption coefficient of these materials in the middle and high frequency bands may be greater than 1

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