Papers by Keyword: Sound Isolation

Abstract: The efficiency of creating and designing noise reduction measures greatly depends on physical, chemical, mechanical and other properties of the selected materials. Some of them and sometimes all of those have a big impact on the general sound insulation of designed measures that also include absorption values predetermining their efficiency.As has been known for a long time, the formed heavy partitions and elements acquire increased sound insulation according to the law of mass, i.e. the heavier is the weight per m2 of the surface (kg/km2), the higher is the sound of insulation.To increase the efficiency of noise reduction in barriers, it is necessary to search for some other properties of the material like design, quality, etc.The article describes how calculations and empirical manipulations facilitate finding an optimal complex construction effectively reducing noise.

Abstract: In this few years with the development of the application of the technique about the fiber sensing in several areas with the bad testing environment, it demands the packaging structure of the fiber interferometer, the center device in the fiber sensing system, with the remarkable capability of vibration and sound isolation. However, the performance index of the such product is still far from the requirement. Based on the method of suspension type we first produce the sound isolation device with the two-part vibration isolation structure. Then during a series of tests we find that it has the remarkable capability of vibration and sound isolation, the capability of sound isolation is higher than 40dB in the whole range of the testing frequencies and the well capability of vibration isolation, which reach to as most as 60dB and at least as 20dB, has been shown above 5Hz.

Abstract: When a proper shunt circuit is connected with a curved piezoelectric membrane, its bended stiffness can be intensified. The system can be used for sound isolation. This mechatronic system， a typically multi-physics problem, was analyzed with FEM in detail. Frequency response characteristics were obtained when shunted with negative-capacitance in parallel. Transmission Loss was presented from 100Hz to 1000Hz. A wonderful sound isolation performance is obtained when shunted with proper values of negative capacitance. Negative capacitance and the loss of piezoelectric material are the main factors of the system. At some frequencies, the sound isolation performance can be increased when a compensated resistance paralleled with negative capacitance. This compensation is dependent on the frequencies. Due to its ordinary electrical parameters, the sound isolation system is realizable in practice. This sound isolation technology can be used in some fields such as windows of room and car.

Abstract: In this study, the basic material for sound absorption was porous nonwoven made of polyester nonwoven and low-melting polyester fiber. Nonwoven was then attached with foam polyurethane as composite plank for sound absorption and sound isolation. We used two microphone impedance tubes for sound absorption test and INSTRON 5566 mechanical testing machine for tensile test. The optimum sound absorption coefficients as 0.67 ± 0.008 was obtained when density of foam polyurethane was 1.0 Kg/m3 with thickness of 20 mm; Polyester nonwoven were 9 layers; and low-melting polyester fiber was 30 wt% with thickness of 10 mm. Specimens obtained the maximum fracture stress when it contained low-melting polyester fiber at 30~40 wt%. The results of this study could be applied in the partitions inside ships, vehicles or buildings.