Sound Reconstruction Research Articles

Assessment of planar array accuracy for 3D sound source reconstruction with Bayesian Focusing

As planar microphone arrays were initially designed for bidimensional sound source localisation, their use for three-dimensional acoustic imaging consistently suffers from a poor resolution along the normal axis. Such a statement is already well documented for beamforming approaches and their declensions. Bearing this in mind, this paper delves into the possibilities offered by inverse methods and especially iterative Bayesian Focusing to tackle this issue and deliver accurate source positions in three dimensions based on planar array measurements only. To this end, an experimental set up is designed: omnidirectional sources are mounted in a wooden mock-up featuring faces at different distances from an 81 MEMs planar array. Based on this measurements, a benchmark study of sound source reconstruction on a 3D mesh of the mock-up is conducted and compared to classical 2D acoustic maps set at different depths. The latter process is declined for various source correlation values and at extended frequency ranges. By doing so, the current paper delivers an overview of the ability to discriminate acoustic sources along the normal axis of a planar array, on a simple and well controlled test case, with a view to provide guidelines for further applications of 3D acoustic imaging on complex geometries.

Spatially extended sound source reconstruction based on the non-synchronous measurements of microphone arrays and Bayesian compressive sensing

The Non-synchronous Measurements (NSM) was proposed to enhance the accuracy of reconstruction and reduce the measurement cost. However, the investigated object of conventional NSM are only sparsely distributed sound sources, and little emphasis placed on the reconstructed accuracy of the spatially extended sound source. In this article, the traditional NSM is further investigated in the spatially extended sound source, and the sound pressure information is reconstructed by Bayesian compressive sensing algorithm (BCS). Firstly, the spatially extended sound source is scanned by moving the rectangular microphone array, and the measurement effects of the array with large aperture and high density are approximately obtained by using NSM technique. Then, BCS is applied to reconstruct sound field by the NSM of sound pressure. The results of numerical simulations provide evidence for the feasibility of applying the proposed investigation to the spatially extended sound source. NSM has advantages in reconstruction accuracy compared with the single measurement. At the same time, the reconstructed sound pressure under NSM can replace the simultaneous measurement (SM) results of multi-array, which avoids the limitation of using reference microphone in increasing the number of channels and spatial layout. The experimental results of the driven steel plate provide additional evidence to support the effectiveness and feasibility of the investigation.

Balancing Conflicting Types of Authenticity in the Reconstruction of Sound and Music in the Installation Work Blikk (1970)

AbstractThis article describes the quest for authenticity in the reconstruction of music, sound, light and logic in the installation work Blikk (The Gaze) by Irma Salo Jæger, Sigurd Berge and Jan Erik Vold. My work on this installation was undertaken at the behest of the National Museum for Art and Architecture in Oslo, Norway, who planned for the installation to be part of the exhibition when the doors opened to their new building in June 2022, following several years of construction. Blikk is described here in context with other works from the same period with which it shares some characteristics, and also with a view on the commissioning institution that represented and promoted radical artistic and curatorial innovation at the time. This frames my discussion of the different authenticity concerns that emerged during the restoration and reconstruction process. In fact, as the project grew from relatively trivial restoration to more involved reconstruction, weighing different authenticity types became the central element of the effort. I have used written, visual and sounding sources in descriptions on how I have balanced these concerns, and the discussion has been supplemented with information on the music technology available to the artists in 1970.

Neglected bilateral multi-ligament knee injury managed by single-stage limb reconstructive surgery: A very rare case report with literature review

Abstract A multi-ligament knee injury (MLKI) can be a devastating injury. A poorly managed, missed, or neglected injury presenting with a painful arthritic crippling unstable limb needs reconstructive surgery. We present a case report of bilateral MLKI presenting with late neglected knee dislocations (KD) in a 37-year-old male. A rotating hinge arthroplasty for a KD5 right knee MLKI and an arthroscopic reconstruction combined with an open repair of the KD3M left knee MLKI have been presented. The strategy for simultaneous reconstructive procedures has been detailed. The preoperative clinical assessment, imaging, anticipated per-operative technical challenges, and adapting a postoperative guided rehabilitation protocol were important considerations. The advantages of a single-stage MLKI management were multi-fold. The single-stage limb reconstructive surgery gave a good functional outcome. A comprehensive review of case reports and studies for chronic or neglected KD provides an update on the various treatment strategies. The bilateral affection allowed for the utilization of contralateral autografts for the reconstructive surgery of the other knee. The combined arthroplasty and ligament repair for two knees as a single-stage procedure allowed an immediate weight-bearing potential to a wheelchair-bound bedridden adult. The precise decision-making, sound reconstruction principles, and meticulous coordinated surgical skills gave a favorable clinical and functional outcome.

Reconstructing the Intangible Cultural Heritage of the Moravian Missions

ABSTRACT This article discusses the application of digital sound technologies within the field of Moravian studies through the case study of Moravian Soundscapes, a digital companion project to the book Moravian Soundscapes: A Sonic History of the Moravian Missions in Early Pennsylvania (Bloomington: Indiana University Press, 2020). Through sound recordings, digital and historic maps, and archival materials from the Moravian Archives in Bethlehem, Pennsylvania, and Herrnhut, Germany, as well as place-based photography, the project documents and reconstructs the soundscapes of eighteenth-century Moravian mission communities in eastern Pennsylvania. The article advocates for the use of sound mapping and sound reconstructions as important methods for understanding the intangible cultural heritage of early Moravian communities.

Vibration reconstruction for a point-excited plate based on acoustic radiation modes and sound pressure measurement

The inverse problem of sound radiation from a vibrating structure is one of the key problems in vibro-acoustics; however, sound source reconstruction with sound pressure measurement still has challenges from sound field assumptions and measurement noise. Due to orthogonality and unrestricted source, Acoustic Radiation Modes (ARMs) are seen as promising basis vectors to realize sound source reconstruction. Here, near-field ARMs obtained by the pressure-velocity method were proposed to construct a series of orthogonal basis vectors for the vibration velocity of a point-excited rectangular plate, and a new procedure of rearrangement and truncation of basis vectors is proposed to obtain the top-ranking vectors with their contribution. Finally, vibration reconstruction is realized with least finite vectors to reach a certain accuracy. Numerical simulations show that vibration reconstruction errors are below 10% with less than 20 orders of basis vectors at frequency range kL ≤ 2π and white noise SNR = 30 dB. The smaller distance of the measuring surface and lower frequency of sound lead to higher reconstruction accuracy and less necessary basis vectors. The factors affecting reconstruction accuracy were also studied by white noise level, amount of basis vectors, and number of measuring points.

Multiple Sound Source Localization, Separation, and Reconstruction by Microphone Array: A DNN-Based Approach

Synchronistical localization, separation, and reconstruction for multiple sound sources are usually necessary in various situations, such as in conference rooms, living rooms, and supermarkets. To improve the intelligibility of speech signals, the application of deep neural networks (DNNs) has achieved considerable success in the area of time-domain signal separation and reconstruction. In this paper, we propose a hybrid microphone array signal processing approach for the nearfield scenario that combines the beamforming technique and DNN. Using this method, the challenge of identifying both the sound source location and content can be overcome. Moreover, the use of a sequenced virtual sound field reconstruction process enables the proposed approach to be quite suitable for a sound field which contains a dominant, stronger sound source and masked, weaker sound sources. Using this strategy, all traceable, mainly sound, sources can be discovered by loops in a given sound field. The operational duration and accuracy of localization are further improved by substituting the broadband weighted multiple signal classification (BW-MUSIC) method for the conventional delay-and-sum (DAS) beamforming algorithm. The effectiveness of the proposed method for localizing and reconstructing speech signals was validated by simulations and experiments with promising results. The localization results were accurate, while the similarity and correlation between the reconstructed and original signals was high.

3-D Sound Image Reproduction Method Based on Spherical Harmonic Expansion for 22.2 Multichannel Audio

In this paper, we propose a three-dimensional (3-D) sound image reproduction method based on spherical harmonic (SH) expansion for 22.2 multichannel audio. 22.2 multichannel audio is a 3-D sound field reproduction system that has been developed for ultra-high definition television (UHDTV). This system can reproduce 3-D sound images by simultaneously driving 22 loudspeakers and two sub-woofers. To control the 3-D sound image, vector base amplitude panning (VBAP) is conventionally used. VBAP can control the direction of 3-D sound image by weighting the input signal and emitting it from three loudspeakers. However, VBAP cannot control the distance of the 3-D sound image because it calculates the weight by only considering the image’s direction. To solve this problem, we propose a novel 3-D sound image reconstruction method based on SH expansion. The proposed method can control both the direction and distance of the 3-D sound image by controlling the sound directivity on the basis of spherical harmonics (SHs) and mode matching. The directivity of the 3-D sound image is obtained in the SH domain. In addition, the distance of the 3-D sound image is represented by the mode strength. The signal obtained by the proposed method is then emitted from loudspeakers and the 3-D sound image can be reproduced accurately with consideration of not only the direction but also the distance. A number of experimental results show that the proposed method can control both the direction and distance of 3-D sound images.

Evaluating low-cost topographic surveys for computations of conveyance

Abstract. Rapid modern technological advancements have led to significant improvements in river monitoring using unmanned aerial vehicles (UAVs), photogrammetric reconstruction software, and low-cost real-time kinematic Global Navigation Satellite System (RTK GNSS) equipment. UAVs allow for the collection of dry bathymetric data in environments that are difficult to access. Low-cost RTK GNSS equipment facilitates accurate measurement of wet bathymetry when combined with subaqueous measuring tools such as acoustic Doppler current profilers (ADCPs). Hydraulic models may be constructed from these data, which in turn can be used for various applications such as water management, forecasting, early warning and disaster preparedness by responsible water authorities, and construction of river rating curves. We hypothesise that the reconstruction of dry terrain with UAV-based photogrammetry combined with RTK GNSS equipment leads to accurate geometries particularly fit for hydraulic understanding and simulation models. This study sought to (1) compare open-source and commercial photogrammetry packages to verify if water authorities with low resource availability have the option to utilise open-source packages without significant compromise on accuracy; (2) assess the impact of variations in the number of ground control points (GCPs) and the distribution of the GCP markers on the quality of digital elevation models (DEMs), with a particular emphasis on characteristics that impact hydraulics; and (3) investigate the impact of using reconstructions based on different GCP numbers on conveyance and hydraulic slope. A novel method which makes use of a simple RTK tie line along the water edge measured using a low-cost but highly accurate GNSS is presented so as to correct the unwanted effect of lens distortion (“doming effect”) and enable the concatenation of geometric data from different sources. Furthermore, we describe how merging of the dry and wet bathymetry can be achieved through gridding based on linear interpolation. We tested our approach over a section of the Luangwa River in Zambia. Results indicate that the open-source software photogrammetry package is capable of producing results that are comparable to commercially available options. We determined that GCPs are essential for vertical accuracy, but also that an increase in the number of GCPs above a limited number of five only moderately increases the accuracy of results, provided the GCPs are well spaced in both the horizontal and vertical dimension. Furthermore, insignificant differences in hydraulic geometries among the various cross sections are observed, corroborating the fact that a limited well-spaced set of GCPs is enough to establish a hydraulically sound reconstruction. However, it appeared necessary to make an additional observation of the hydraulic slope. A slope derived merely from the UAV survey was shown to be prone to considerable errors caused by lens distortion. Combination of the photogrammetry results with the RTK GNSS tie line was shown to be essential to correct the slope and made the reconstruction suitable for hydraulic model setup.

A block bayesian compressive sensing method based on the equivalent source method for near-field acoustic holography

The conventional equivalent source method for near-field acoustic holography is an effective noise diagnosis method using microphone array. However, its performance is limited by microphone spacing, so the effect is unsatisfied when the wave number is high. In this paper, to broaden the frequency suitability and improve the performance of sound source reconstruction with low signal-to-noise ratios, a block Bayesian compressive sensing method based on the equivalent source method is proposed. Numerical results show that this proposed method has a good reconstruction performance and makes wideband reconstruction possible. By changing the frequency, location, and signal-to-noise ratio of the sound source, the reconstruction performance of the proposed method can remain stable. Finally, the validity and practicability of the proposed method are verified by experiments.

A New Method for Sound Generation Based on Digital Sound Reconstruction

In this paper, we consider the general idea of Digital Sound Reconstruction (DSR) and analyze its inherent limitations. Based on this discussion, a new method which we call Advanced Digital Sound Reconstruction (ADSR) is introduced and analyzed in detail. This method aims to overcome the problems of classical DSR by introducing shutter gates and focuses on sound generation in the low-frequency domain. Combining the idea of classical DSR with a redirection mechanism leads to a gain of 20[Formula: see text]dB per decade regarding the sound pressure for decreasing frequency values. We present multiple array designs and possible embodiments for ADSR as well as an in depth view of excitation and optimization approaches. Finally, numerical investigations are used in order to demonstrate the potential of ADSR especially in the mid- to low-frequency range.

Sparsity-enhanced equivalent source method for acoustic source reconstruction via the Generalized Minimax-Concave penalty

The Equivalent Source Method (ESM) is a powerful technique for acoustic source reconstruction, which has been widely used in noise control and machinery fault detection. Because the inverse acoustic source reconstruction problem is typically ill-conditioned, regularization techniques are often adopted in ESM to achieve meaningful solutions. Based on the sparse distribution assumption of acoustic sources, sparse regularization can be utilized in ESM to promote the spatial resolution of reconstructed results. Existing sparse ESMs often adopt convex l1 norm or nonconvex lp norm as the regularization terms. However, l1 norm-regularized ESM suffers from an insufficient sparsity-inducing problem, which decreases the spatial resolution and reconstruction accuracy. Meanwhile, reconstructed results of lp norm-regularized ESM are often unstable due to multiple local minimas. In this paper, a sparsity-enhanced ESM is proposed, which introduces a nonconvex Generalized Minimax-Concave (GMC) penalty into ESM as the regularization term. The GMC penalty can enhance the sparsity of solutions and simultaneously maintain the convexity of the overall objective function in acoustic source reconstruction. Consequently, the GMC penalty-regularized ESM can improve the spatial resolution and reconstruction accuracy of the reconstructed results. To solve the acoustic source reconstruction problem rapidly, a computation framework based on Alternating Direction Method of Multipliers (ADMM) is derived. Simulation studies indicate that the proposed method can improve the acoustic source reconstruction accuracy in a wide frequency band, compared with existing l1 and lp norm-regularized ESMs. Two experimental cases further verify that the proposed sparsity-enhanced ESM can effectively reconstruct the acoustic sources with high spatial resolution and reconstruction accuracy at higher frequencies.

Model-data-driven image reconstruction with neural networks for ultrasound computed tomography breast imaging

With the goal of developing an accurate and fast image reconstruction algorithm for ultrasound computed tomography, we combine elements of model- and data-driven approaches and propose a learned method which addresses the disadvantages of both approaches. We design a deep neural network which accounts for a nonlinear forward operator and primal-dual algorithm by its inherent network architecture. The network is trained end-to-end, with ultrasound pressure field data as input to get directly an optimized reconstruction of speed of sound and attenuation images. The training and test data are based on a set of Optical and Acoustic Breast Phantom Database, where we use the image as ground truth and simulate pressure field data according to our forward model. Extensive experiments show that our method achieves significant improvements over state-of-the-art reconstruction methods in this field. Experiments show that the proposed algorithm improves the measures structural similarity measure (SSIM) from 0.74 to 0.95 and root mean squared error (RMSE) from 0.13 to 0.09 on average concerning the speed of sound reconstruction, while it improves the SSIM from 0.60 to 0.94 and RMSE from 0.24 to 0.10 on average in attenuation reconstruction.

A sound source reconstruction approach based on the machine vision and inverse patch transfer functions method

The inverse patch transfer functions (iPTF) method can realize local reconstruction of a vibrating structure in non-anechoic environments, and the geometrical shape of the reconstruction area could be irregular as long as it is known. However, the shape of the non-planar reconstruction area is not easy to be obtained in practice, which is adverse to its application in the situ tests. To achieve the sound source reconstruction of the local area with unknown shape in non-anechoic environments, a hybrid method that combines the machine vision and the iPTF method is proposed. The machine vision technology is applied to facilitate the boundary modeling of a target radiation segment. It makes use of the BundleFusion method with an RGB-D camera to accomplish the 3D reconstruction of the target area, as well as the localization of microphones. A virtual cavity consisting of the target area, virtual measurement surface, and the gap between them could be constructed automatically. Consequently, the impedance matrix of the virtual cavity is obtained based on the boundary integral equation with the adoption of the free field Green’s function. A microphone array mounted up with a rigid masker is applied in the iPTF method, which can form the rigid Neumann boundary condition on the masker. A simulation is first carried out to investigate the influence of 3D reconstruction errors of the machine vision technology on the sound source reconstruction. Then, two experiments are performed to validate the feasibility and effectiveness of the reconstruction in noisy environments. One is conducted in the semi-anechoic room with a cylindrical radiator, and a loudspeaker is put aside as the interference source. The other is conducted in the cabin of an aircraft under cruising condition. It is demonstrated that the proposed method can realize the normal velocity reconstruction without prior geometry knowledge of the target area, and the magnitude and distribution of the dominant sound source could be reconstructed accurately.

Investigation of a new method for sound generation \u2013 Advanced Digital Sound Reconstruction

The current loudspeaker market has a high demand for portable audio devices. Hence, the miniaturization of loudspeakers (microspeakers) is of great importance for manufacturers. Traditional loudspeakers – for example the electrodynamic loudspeaker – are the forerunners, but so-called MEMS loudspeakers (Micro-Electro-Mechanical-System) have emerged recently. MEMS devices have already been used for sensors (i.e., microphones) to a great extend due to their advantages regarding form factor and production efficiency. Albeit additional challenges for actuators like moving enough air with a microstructure – as it is the case for a loudspeaker – the usage of MEMS technology for loudspeakers is very attractive.Since especially low-frequency audio signals often pose problems for microspeakers, this article focuses on a new sound generation technique called Advanced Digital Sound Reconstruction (ADSR) which is especially well-suited for low-frequency audio signals since ADSR can generate more volume displacement relative to its size. Based on a general description of the principle, an outlook of the possibilities regarding achievable sound pressure compared to the classical excitation scheme is derived. Furthermore, measurements are presented, which aim to prove the concept of ADSR based on already existing actuators.

A bio-inspired geometric model for sound reconstruction

The reconstruction mechanisms built by the human auditory system during sound reconstruction are still a matter of debate. The purpose of this study is to propose a mathematical model of sound reconstruction based on the functional architecture of the auditory cortex (A1). The model is inspired by the geometrical modelling of vision, which has undergone a great development in the last ten years. There are, however, fundamental dissimilarities, due to the different role played by time and the different group of symmetries. The algorithm transforms the degraded sound in an ‘image’ in the time–frequency domain via a short-time Fourier transform. Such an image is then lifted to the Heisenberg group and is reconstructed via a Wilson–Cowan integro-differential equation. Preliminary numerical experiments are provided, showing the good reconstruction properties of the algorithm on synthetic sounds concentrated around two frequencies.

Millimeter-Wave Bat for Mapping and Quantifying Micromotions in Full Field of View.

Echolocating bats possess remarkable capability of multitarget spatial localization and micromotion sensing in a full field of view (FFOV) even in cluttered environments. Artificial technologies with such capability are highly desirable for various fields. However, current techniques such as visual sensing and laser scanning suffer from numerous fundamental problems. Here, we develop a bioinspired concept of millimeter-wave (mmWave) full-field micromotion sensing, creating a unique mmWave Bat (“mmWBat”), which can map and quantify tiny motions spanning macroscopic to μm length scales of full-field targets simultaneously and accurately. In mmWBat, we show that the micromotions can be measured via the interferometric phase evolution tracking from range-angle joint dimension, integrating with full-field localization and tricky clutter elimination. With our approach, we demonstrate the capacity to solve challenges in three disparate applications: multiperson vital sign monitoring, full-field mechanical vibration measurement, and multiple sound source localization and reconstruction (radiofrequency microphone). Our work could potentially revolutionize full-field micromotion monitoring in a wide spectrum of applications, while may inspiring novel biomimetic wireless sensing systems.

ПРО ІСТОРІЮ ТА СУЧАСНИЙ СТАН ЕРАЗМОВОЇ ВИМОВИ ДАВНЬОГРЕЦЬКОЇ МОВИ

The article presents the results of a study of some aspects of the formation and use of Erasmian pronunciation of the Ancient Greek language (in particular, the vagueness of the concept, lack of standardization and certain linguistic inconsistencies), based on analysis of the original work of Erasmus of Rotterdam "Dē rēctā latīnī graecīque sermōnis prōnūntiātiōne dialogus" and works devoted to the analysis of Ancient Greek pronunciation and the history of the Greek language in general. Attention is paid to the non grata status that Erasmian pronunciation has in Greece, as well as to alternative views on the origins of the mentioned work of Erasmus, to which, from the 16th century to the present day, opponents of both the Erasmian pronunciation and the reconstructed systems in general refer. Some important facts from the history of Erasmian pronunciation are outlined, in particular that Erasmus was not the pioneer in the search for the "true" pronunciation of Classical Greek (a Spanish humanist Antonio de Nebrija researched this issue at least a quarter of a century before the publication of Erasmus's work); in writing the Dialogue, Erasmus relied on the work of his predecessors, with whom he was maintaining friendly communication; Erasmus's work was not a clear enough proposal for a new reformed system, and the scholar himself continued to use the Byzantine pronunciation and recognized its status. The article gives examples of some differences between variants of Erasmian pronunciation. It is concluded that the Erasmian pronunciation from its inception was not a clearly defined system, and, despite the revolutionary and impressive breakthrough of this linguistic initiative, had some errors, which were compensated by later attempts in the Ancient Greek pronunciation reconstruction in the 19th–21st centuries. It is suggested that, given the significant non-uniformity of present-day Erasmian pronunciation variants (which sometimes leads to complications in international communication between specialists), it is advisable to use, or at least be familiar with modern, more clearly defined and scientifically sound reconstructions, and / or Modern Greek pronunciation which is especially important for rapport with Greek colleagues in classical studies.

The ecological framework as part of the land and property complex of an industrial city (on the example of an urban district of Tobolsk)

In modern urban conditions with intensive industrial production affecting the life and health of people, the authorities of many cities have thought about holding activities aimed at improving the ecological component of the urban environment. One of such activities may be the creation or improvement of the ecological framework of the city. This article discusses the features of the ecological framework in the industrial city of Tobolsk. A number of tasks that are faced by the City Administration were formulated; those must be solved using sound reconstruction methods of urban territorial and functional structures. The role of the ecological framework of the urban area is considered as the possibility of avoiding the environmental problems’ emergence and preserving the ability of the territorial system as an independent land and property complex to develop.

Glass-blowing Production Models in Museum Expositions

Glassware in the territory of Ukraine is very old, and it reaches the limits of the 4-3rdmillennium BC, samples of glass beads from Usatovo and Yamna burials in particular. They should have been of mixed Egyptian-Mesopotamian origin and were a by-product of metallurgy (it was due to the interaction with copper that these glassware acquired the blue-greenish colour). The real glassware in Ukraine appears in Scythian-Antique times. In Middle Ages and in Modern Age it was already a professional production. Therefore, the lack of representation of glass-blowing industry in museum expositions is surprising, as well as the lack of modelling of the glass production process. Thus, the purpose of this article is to develop the foundations of relevant scientifically sound reconstructions and create options for graphic reproduction of glass-blowing workshops.To create a glass furnace model, one must first choose the age of furnace to be reconstructed and modelled (the text of the article provides several regional and chronological examples). For the most ancient periods, two main schools of glassmaking considered: Middle Eastern and Egyptian; Syrian, Roman capital and provincial Roman schools – for the Roman age. Medieval schools were: Byzantine, Western European, Old Rus, and Central Asian. The earlier was the school, the less indications of it we have.It is reasonable to make a partial section of the furnace model in order to show its internal structure. It seems necessary to make a stand representing 3-D printed copies of glassblowing tools next to the layout. Accompanying the text layout is necessary as well, which should reveal the features of the glass-blowing craft. It makes sense to place glass technology information, its technical characteristics, and features of the main schools of glassmaking for increased attractiveness. It also makes sense to display the needed ways of processing hot glass and whirling it on the glassblowing pipe on the stand.Manuscript received 12.03.2020