A sound insulation and amplification device for force-excited reverberation box wall

Abstract

The invention provides a sound insulation and amplifying device for the wall surface of a force-excited reverberation box, which includes a sound insulation cover, a first flange, an air extraction valve, an outlet hole, a cylinder, and a second flange. The sound insulation cover is hemispherical. There is a first flange on the bottom of the sound insulation cover, and a groove is set in the first flange, the exhaust valve is on the sound insulation cover, the outlet hole is on the sound insulation cover, the cylinder is located in the reverberation box, the axis of the cylinder and the force excitation The directions are coincident, there is a second flange at the bottom of the cylinder, and grooves are opened in the second flange, and there are dimples and through holes from the middle section of the cylinder to the front end; this force excites the sound insulation and amplification device on the wall of the reverberation box The vacuum formed by the sound cover isolates the noise radiated from the force excitation source to the air; the ultrasonic horn mechanism composed of cylinders is used to amplify the excitation effect of the force excitation source, thereby generating a higher sound pressure level in the reverberation box and improving the experimental performance. The signal-to-noise ratio of the test process; use the through holes and dimples in the middle and front part of the cylinder to solve the cavitation phenomenon that is easy to occur when the cylinder is in the process of strong vibration.

Description

technical field [0001] The invention relates to a sound insulation and amplifying device for force-exciting the wall surface of a reverberation box, which belongs to the field of acoustic measurement. Background technique [0002] Usually, the method of measuring the sound insulation performance of the acoustic coating under the condition of low-frequency random incidence is to put a sound source in a reverberation box, and use the sound source to generate sound waves incident in all directions in the reverberation box, so as to realize the sound insulation of the acoustic coating. The sound waves transmitted through the acoustic covering layer are received by another reverberation box. After obtaining the spatial average sound pressure levels in the two reverberation boxes respectively, the relative comparison method is used to obtain the insulation of the acoustic covering layer. sound coefficient. Due to the cut-off frequency of the reverberation box, there is also a low...

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Problems solved by technology

[0003] First, because the point force only excites one point of the side wall, the local vibration of this point is very strong, while the vibration of other parts is very weak, especially when the box wall is thin, so that cavitation occurs, that is, the water molecules are separated from the wall , resulting in a decrease in radiation efficiency, making the sound pressure level in the reverberation box low;

[0004] Second, Liyuan itself will produce strong single-frequency or broadband noise. This single-frequency or broadband noise can easily propagate through the water medium in the reverberation box, and then be heard by the water in the reverberation box on the other side. Receiver

Although theoretically this noise causes the signal amplitude of the hydrophone to be very small (the sound energy incident from air to water is about one-thousandth of its direct incident sound energy in water), these noises will cause some peaks on the spectrum

Since sound insulation is a relative quantity, these peaks can lead to an overestimation of the sound insulation of the acoustic cover layer

[0005] Third, the force source only acts on the side wall of the reverberation box. Although random incident sound waves can be generated in the reverberation box, the sound waves at the cut-off frequency of the reverberation box (action of the sound source) will still be affected by the reverberation box. The influence of the cut-off of internal sound energy makes the sound field not uniform enough

[0006] A high-speed train interior noise analysis and prediction method (application number: CN201610008123.9) discloses a high-speed train interior noise analysis and prediction method, which overcomes the limitation of the upper limit of the frequency domain in the existing method, and has not considered the amplification of sound energy question

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