Sound insulation and amplification device for wall surface of force excitation reverberation box

Abstract

The invention provides a sound insulation and amplification device for a wall surface of a force excitation reverberation box. The device comprises an acoustic shield, a first flange, an extraction valve, a wire outlet hole, a cylinder and a second flange; the acoustic shield is hemispherical, and the first flange is arranged at the bottom of the acoustic shield; a groove is formed in the first flange, and the extraction valve is arranged on the acoustic shield; the wire outlet hole is formed in the acoustic shield, and the cylinder is located in the reverberation box, wherein the axis of thecylinder coincides with the force excitation direction; the second flange is arranged at the bottom of the cylinder, and a recess and a through hole are formed from the middle section to the front end. According to the sound insulation and amplification device for the wall surface of the force excitation reverberation box, the noise radiated by a force excitation source to air is isolated by utilizing vacuum formed by the acoustic shield; an ultrasonic-like amplitude-change pole mechanism composed of the cylinder is utilized to amplify the excitation effect of an excitation source, so a highersound pressure level is generated in the reverberation box, and the signal-to-noise ratio in the experimental test process is improved; by means of the through hole and the recess in the middle-frontsection of the cylinder, the cavitation phenomenon easily occurring in the strong vibration process of the cylinder is avoided.

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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