Noise Attenuation Methods Research Articles

Noise control of an acoustic enclosure covered by a double-wall structure with shallow gap: Design of resonator-like cavities

The present study addresses the possibility of using resonator-like cavities for noise attenuation of an acoustic enclosure covered by a double-wall structure with shallow gap. Different from the conventional design of using Helmholtz resonators, a set of coupled equation describing resonator-like cavity is integrated into the vibro-acoustic model, under which the modes in a broad frequency range will be controlled. Based on the tuned weighting coefficient and the acoustic potential energy, an objective function is developed to optimize parameters (number and location) of resonator-like cavities. The effect of shallow gap on the first two dominant modes of the coupled system and energy transmission is investigated. Simulation results indicate the effectiveness of the proposed method for noise attenuation, which might be of direct benefit to engineering applications.

Design and Acoustic Performance of a Drum Practice Music Studio

Minimising the impact of music practice and “Garage Band” performances upon neighbours in a residential area is challenging in terms of noise emissions from musical instruments, but particularly so when drums and percussion instruments are involved. Normal residential building façades and roofing designs offer limited low frequency noise attenuation and domestic building construction methods can severely compromise the performance of seemingly adequate partition construction details. This paper presents the results of design, construction and testing activities for a private drum studio that was required to meet stringent boundary noise emission targets in order to comply with local council Development Application requirements. High transmission loss lightweight partition test data is provided for the as-built final installation, along with details of cavity absorption, panel damping and vibration isolation treatments that contributed to maximising façade sound reduction performance. A range of room internal absorption treatments, including low frequency “tube traps”, corner traps and diffusers were successfully employed to achieve compliance with BBC recommended reverberation times for small recording studios

A noise attenuation method for medium-energy electron measurements in the radiation belt

From the viewpoint of plasma particle measurements in the radiation belt, background noise is a serious problem. High-energy particles penetrating the sensor shielding generate spurious signals, and their count rate often can be comparable to the true signals. In order to attenuate such background noise during medium-energy (5–83 keV) electron measurements, we propose the double energy analyses (DEA) method. DEA is conducted by a combination of an electrostatic analyser (ESA) and avalanche photo-diodes (APDs); ESA and APD independently determine the energy of each incoming particle. By using the DEA method, therefore, the penetrating particles can be rejected when the two energy determinations are inconsistent; spurious noise are caused only when the deposited energy at an APD is by chance consistent with the measured energy by ESA. We formulate the noise count rate and show the advantage of DEA method quantitatively.

Active noise cancellation stability solution

The method of noise attenuation comprises the steps of generating a noise canceling signal, sensing for an system condition, and ceasing the generation of the noise canceling based upon the system condition. This method is embodied in a system that includes an air induction body, a speaker in proximity to the air induction body, a sensor for sensing a system condition, and a control unit with a noise cancellation feature. The control unit is in communication with both the speaker and the sensor. Based upon the sensed system condition, the control unit may disable the noise cancellation feature.

Three-State Locally Adaptive Texture Preserving Filter for Radar and Optical Image Processing

Textural features are one of the most important types of useful information contained in images. In practice, these features are commonly masked by noise. Relatively little attention has been paid to texture preserving properties of noise attenuation methods. This stimulates solving the following tasks: (1) to analyze the texture preservation properties of various filters; and (2) to design image processing methods capable to preserve texture features well and to effectively reduce noise. This paper deals with examining texture feature preserving properties of different filters. The study is performed for a set of texture samples and different noise variances. The locally adaptive three-state schemes are proposed for which texture is considered as a particular class. For detection of texture regions, several classifiers are proposed and analyzed. As shown, an appropriate trade-off of the designed filter properties is provided. This is demonstrated quantitatively for artificial test images and is confirmed visually for real-life images.

Comparative testing of acoustic properties of cinder blocks packed with recycled materials for noise barrier applications

In the search for more effective noise attenuation methods, a number of candidate materials for road noise barriers and partition walls were tested at the Cooper Union Acoustics Research Center in a specially constructed enclosure divided into two sections by a wall constructed of these materials. The transmission losses of cinder blocks filled with various recycled materials constitute the acoustical property of principal interest. Three tests were executed for each type of material: (1) transmission loss measurements; (2) absorption coefficient measurements; and (3) diffraction effects. The intended applications of the designed materials are as noise barriers for urban highways and subway stations, and as partition walls for factories, classrooms, libraries, etc. Recycled materials experimented with would normally end up in land fills or incinerators. [See NOISE-CON Proceedings for full paper.]

Improvement of noise attenuation of autoassociative memory using two‐stepped association procedure

AbstractBy means of autoassociative memory we can read out (or associate) original complete information from incomplete memorized information. If we assume that incomplete memorized information is made of additive noise and original information, autoassociative memory can be regarded as a noise attenuation filter. In this paper, using the twostepped association procedure we proposed earlier, we compose autoassociative memory and with its characteristics, propose a new method to improve the ability of noise attenuation in associative memory. This method restricts the width of the associative output space by changing the dimensionality of the mediate vectors in the twostepped association procedure in accordance with noise condition. This minimizes the influence of noise on the associative output as long as inferiority of information will not occur. In this paper, to examine the ability of this noise attenuation method, we calculate the mean square error (that is, correctness of association or ability of noise attenuation) of association theoretically and execute the association experiment (computer simulation) using the actual image information as the memorized information. From the results, it is clear that our proposed method has high ability of association (ability of noise attenuation) compared with the conventional methods.