Path Of Sound Waves Research Articles

Disturbance in the protein landscape of cochlear perilymph in an Alzheimer's disease mouse model.

Hearing loss is a pivotal risk factor for dementia. It has recently emerged that a disruption in the intercommunication between the cochlea and brain is a key process in the initiation and progression of this disease. However, whether the cochlear properties can be influenced by pathological signals associated with dementia remains unclear. In this study, using a mouse model of Alzheimer's disease (AD), we investigated the impacts of the AD-like amyloid β (Aβ) pathology in the brain on the cochlea. Despite little detectable change in the age-related shift of the hearing threshold, we observed quantitative and qualitative alterations in the protein profile in perilymph, an extracellular fluid that fills the path of sound waves in the cochlea. Our findings highlight the potential contribution of Aβ pathology in the brain to the disturbance of cochlear homeostasis.

Design of multi-auxetic microstructures for sound absorbing applications

Auxetics are known to improve sound absorption performance due to their irregular porous structure. However, it is still difficult to control the porous microstructure to absorb a specific frequency range, although mechanical rigidity and improved sound absorption performance were achieved by manufacturing polyurethane foam for auxetics. Hence, we report, for a first time, a multi-auxetic porous microstructure fabricated via a triaxial thermal compression method applied simultaneously with two or more different compression ratios. The upper and lower parts of the multi-auxetic foam have two or more different positive or negative Poisson’s ratio, respectively. Consequently, the manufactured multi-auxetic foam has a single negative Poisson’s ratio property with enhanced sound absorption performance in the low-frequency range by twisting and forming a long sound wave path. Moreover, it was confirmed that the multi-auxetic sound absorber has an adjustable sound absorbing performance in a specific frequency range according to the difference in variety of pore sizes for each upper or lower part as well as the direction of incidence of the sound waves. This work suggests that the multi-auxetic porous microstructure can be mass-produced by a simple and fast manufacturing method, and it can be provided at a low price by manipulating the cellular structure of the conventional material.

Sound insulation of a novel laminated polymer matrix composite containing metallic hollow spheres based on phononic crystal structure design

AbstractAs a noval functional material designed and prepared artificially, one‐dimensional phononic crystal has a great prospect in the field of noise reduction. In this study, a novel one‐dimensional phononic crystal metamaterial based on the metallic hollow spheres (MHS)/polymer matrix laminated composites was designed and prepared. The result of impedance tube test shows that the laminated composite has excellent sound insulation performance. The incident direction of sound waves has little effect on the sound insulation performance of the laminated composites. The average sound insulation of MHSP/SR‐LC (MHSP side) was 44.4% higher than that of SR and 272.0% higher than that of PU. After analysis, it can be found that the average sound insulation of laminated composites increases with the acoustic impedance increasing, but the equivalent mass density and equivalent bulk modulus have little effect on it. The metallic hollow spheres can increase the sound energy loss by extending the transmission path of sound waves, andit can also improve the sound insulation by changing the density, elastic, and hardness of SR and PU matrix to increase the resonance strength of the spring‐mass oscillator. This work may open up new possibilities for the development of novel acoustic materials applied in noise control.

Numerical and experimental study on temperature field reconstruction based on acoustic tomography

Obtaining a high-quality measurement of the temperature distribution is crucial to optimally adjust the combustion in a boiler. Acoustic tomography (AT) can be used to measure the temperature distribution from multipath acoustic time of flight (TOF). The reconstructed model and TOF measurement are crucial for practical applications of AT measurement. In this paper, a new temperature field reconstruction model based on radial basis function approximation with polynomial reproduction is presented for solving the AT inverse problem. In our reconstructed model, we also consider the refraction effect of sound wave paths in the non-uniform temperature field. A truncated singular value decomposition reconstruction method is used to improve the reconstruction quality and the anti-noise ability. In addition, a generalized cross-correlation with second correlation is applied to estimate the TOF to effectively suppress interference from noise. Numerical simulations and experimental study are implemented to evaluate the effectiveness of the proposed reconstruction method. The numerical results indicate that our model considering the refraction effect can reconstruct temperature distributions with higher accuracy and better anti-noise ability compared with other existing methods. The experimental results are compared against thermocouple measurements, which show that when considering the refraction effect, the proposed method has superior reconstruction performance than methods without the refraction effect.

Research on Temperature Field Reconstruction Based on RBF Approximation with Polynomial Reproduction Considering the Refraction Effect of Sound Wave Paths

The temperature field distribution directly reflects the combustion condition in a furnace．In this paper, acoustic thermometry to reconstruct temperature distribution is investigated. A method based on radial basis function... | Find, read and cite all the research you need on Tech Science Press

A Study on Reconstructing Temperature Field

This paper puts forward a new algorithm based on RBF neural network to reconstruct three-dimensional temperature field.The algorithm uses three-dimension Discrete Cosine Transform on temperature field,and establishes a mapping relation between low order term coefficient vector and sound wave path average temperature vector,then implements the mapping relation using radical basis function neural network.Finally three-dimensional temperature field was reconstructed by using Inverse three-dimension Discrete Cosine Transform.Simulation results show that the algorithm features high precision.

HORN-LOADED ACOUSTIC LINE SOURCE

A sound reproduction system is disclosed in which a sound enclosure defines a soundwave path having a first end, a second open end and at least one bend therebetween. At least one driver is provided at the first end for producing a driver soundwave that is confined by the sound enclosure for travel along the soundwave path. At least one baffle member is situated in the soundwave path, defining a reflective surface of preselected shape that reflects and constricts the soundwave therethrough.

Loudspeaker sound modulation appliance

In combination with a loudspeaker assembly that includes a speaker diaphragm that is displaced to produce sound, the combination comprising a spinner element mounted to rotate in the path of sound waves produced by the speaker diaphragm; and a rotary drive for rotating the spinner, the spinner defining sound wave passing through openings, in said path.

Loudspeaker sound modulation apparatus

A loudspeaker assembly includes a speaker diaphragm that is displaced to produce sound, and a spinner element mounted to rotate in the path of sound waves produced by the speaker diaphragm, the spinner defining sound wave passing through openings, in said path. Illumination of interior structure, may be provided, for visual effect through openings defined between rotating spinner arms, and between non-rotating grille arms. Different combinations of grilles and spinners are easily enabled by mounting structure.

Acoustic computer tomographic pyrometry for two-dimensional measurementof gases taking into account the effect of refraction of sound wavepaths

The algorithm which takes into account the effect of refraction ofsound wave paths for acoustic computer tomography (CT) is developed.Incorporating the algorithm of refraction into ordinary CT algorithms whichare based on Fourier transformation is very difficult. In this paper, theleast-squares method, which is capable of considering the refraction effect,is employed to reconstruct the two-dimensional temperature distribution. Therefraction effect is solved by writing a set of differential equations whichis derived from Fermat's theorem and the calculus of variations. It isimpossible to carry out refraction analysis and the reconstruction oftemperature distribution simultaneously, so the problem is solved using theiteration method. The measurement field is assumed to take the shape of acircle and 16 speakers, also serving as the receivers, are set around itisometrically. The algorithm is checked through computer simulation withvarious kinds of temperature distributions. It is shown that the presentmethod which takes into account the algorithm of the refraction effect canreconstruct temperature distributions with much greater accuracy than canmethods which do not include the refraction effect.

Acoustic CT Algorithm for 2-D Temperature Measurement of Gases Taking Account of Refraction Effect of Sound Wave Paths.

The Algorithm to solve refraction effect of sound wave paths for acoustic CT (computer tomography) is developed. Ordinary CT algorithm, that is, kinds of Fourier transformation, is hard to take into account of deflection of projection beams. In this paper, the least square method is employed to reconstruct two-dimensional temperature distribution from refracted beams due to refraction effect. Refracted sound wave paths are analyzed by Fermat's theorem. Refraction analysis and reconstruction of temperature distribution are impossible to do simultaneously and they are solved with iteration method. The algorithm is confirmed by the data made by computer simulation. The measurement field is assumed as circle and sixteen speakers are set around it. Those speakers are used also as receivers. Measurement field is divided into nine for lateral and vertical directions. The results excluding and including the refraction effect are compared. It is shown that the accuracy of the latter case is extremely superior than the former one.

Acoustic levitation and methods for manipulating levitated objects

Objects are levitated in a sound system substantially free of reverberation and reflection by positioning a small reflector in the path of sound waves. Interference between the primary waves and reflected waves creates a localized zone of minimized energy closely adjacent to the reflector in which an object may be stably levitated. The energy well thus produced is not dependent upon distance from the sound source, and the levitated object may be moved in any direction by moving the reflector. A plurality of reflectors may be employed to manipulate and combine levitated materials, and improvements in the processing of levitated objects are also achieved.