Acoustic Microphone Array Research Articles

A Distributed Clustering Scheme for Dense Wireless Sensor Networks

Abstract: A sensor node, also known as an Alfeo (mainly in North America), is a sensor network node capable of processing, collecting sensor data, and communicating with other connected nodes in the network. Alpheus is a node, but a node is not always a point. Each sensor node has a microprocessor and some memory. In addition, each sensor node has one or more sensor devices such as acoustic sensors, microphone arrays, and video cameras, infrared, seismic or magnetic sensors. However, dead batteries in sensor nodes are difficult to replace. A typical sensor node consumes part of its energy during wireless communication. This research paper proposes to develop a well estimated distributed clustering model for dense wireless sensor network fields that provides improved performance over the existing clustering algorithm LEACH. The two robbery concepts behind the proposed system are the hierarchical distributed clustering mechanism and the threshold concept. Energy consumption is significantly reduced, which significantly extends the life of sensor nodes

Distributed Sound Transmission and Smart City Planning Management Based on Convolutional Neural Network

In this article, we provide a detection method based on a convolutional neural network algorithm. Preamble detection is very important in underwater acoustic communication. Only the preamble signal can trigger the receiving operation to effectively process the acoustic data received underwater. The prerequisite for specifying the joint position of the distributed acoustic multiarray is the mutual calibration calculation of each array. This paper designs and develops a prototype system for microphone array sound source positioning and provides an optimized system to obtain calibration source mapping points for distributed sound transmission mutual calibration, and for mutual distributed acoustic microphone arrays, use epipolar geometry and normalization algorithm for calibration to provide a basis for a mutual calibration calculation model and functional module design. Finally, perform numerical simulation verification. It provides a design plan and implementation method for the Internet-based smart city education system, aiming to achieve professional education and educational needs related to the Internet of Things. First, we will take Internet application technology as an example to analyze the functional requirements of the education system, including the positioning of human resource development, integrated sensors, C/C#/Java application development technology, and other technical means to realize the smart city education system. Based on the theory of business management, this paper studies the business planning issues of smart city construction. The main content is divided into three parts: business composition and management and planning management. This is an important part of business. It plays a decisive role in the overall planning and implementation stage and protects the implementation progress of the project and ensures the quality of the project by including important content.

Three-dimensional location and attitude estimation using asynchronous acoustic beacons and microphone array

Three-dimensional location and attitude estimation using asynchronous acoustic beacons and microphone array

Battlefield acoustics: Applications and challenges

Some primary objectives of research and development for battlefield acoustic sensing include the optimization of sensors, arrays, and signal processing algorithms for the detection, localization, and classification of diverse broadband and transient threats in complex environments. Time-difference-of-arrival and frequency domain signal processing techniques using distributed microphone arrays allow sound source localization and tracking through triangulation in the 3-D space. This presentation will introduce general applications of broadband acoustic and infrasonic microphone arrays, acoustic particle velocity sensors, geophones, propagation environment effects and wind mitigation methods.

Identifyinggrindingmilldynamicsusingacousticbeamformingandnumericalmodelling

Online measurement of the grinding dynamics within mills is crucial for its optimal operation in terms of reduced liner wear and maximised throughput. Non-invasive measurement techniques, such as the noise-based acoustic beamforming may be utilised to more effectively identify charge dynamics, which is studied in this paper. A pilot mill and an associated acoustic microphone array were purposely designed and constructed, and a suite of experiments with various mill charge compositions and mill speeds was conducted. Numerical modelling of the pilot mill with a coupled discrete element modelling (DEM) and smoothed particle hydrodynamics (SPH) was also performed to compare the acoustic beamforming results. It was indicated that level of the acoustic noise generated during mill operation is more associated with steel ball filling rate rather than the mill speed. Beamforming results suggested that grinding dynamics and mill charge shape can be reconstructed from acoustic noise measured at 500 Hz frequency band. Numerical modelling indicated that charge throw trajectory was more susceptible to mill speed than the ball filling rate. DEM contact parameters showed negligible effect on altering the grinding dynamics. In addition, comparison between numerical modelling and acoustic beamforming showed analogous results. The outcome of this study suggested that acoustic beamforming can be utilised for online detection of grinding dynamics in operation.

Classification, positioning, and tracking of drones by HMM using acoustic circular microphone array beamforming

This paper addresses issues with monitoring systems that identify and track illegal drones. The development of drone technologies promotes the widespread commercial application of drones. However, the ability of a drone to carry explosives and other destructive materials may pose serious threats to public safety. In order to reduce these threats, we propose an acoustic-based scheme for positioning and tracking of illegal drones. Our proposed scheme has three main focal points. First, we scan the sky with switched beamforming to find sound sources and record the sounds using a microphone array; second, we perform classification with a hidden Markov model (HMM) in order to know whether the sound is a drone or something else. Finally, if the sound source is a drone, we use its recorded sound as a reference signal for tracking based on adaptive beamforming. Simulations are conducted under both ideal conditions (without background noise and interference sounds) and non-ideal conditions (with background noise and interference sounds), and we evaluate the performance when tracking illegal drones.

Experimental studies of sound propagation over vertical and slanted paths in a turbulent atmosphere

Sound propagation over vertical and slanted paths differs from horizontal paths due to the height dependence of turbulence parameters and atmospheric stratification. Vertical and slanted paths are important for several applications, such as localization of unattended aerial systems (UASs) with ground-based acoustic microphone arrays, detection of ground-based sources with elevated arrays, and the effect of atmospheric turbulence on sonic booms. This paper describes a comprehensive experiment on near-vertical sound propagation conducted over five days in September 2018 at the National Wind Technology Center (NWTC), located near Boulder, CO. The experiment involved the NWTC 135-m meteorological tower with meteorological instruments installed at 17 heights. Nine microphones were located on three horizontal booms attached to the tower at different heights, and a speaker was placed on the ground. Two reference microphones where located near the speaker. About 65% of the time, the speaker transmitted nine or twelve tones. During the remaining time, 6-ms chirps were transmitted. A preliminary analysis of the signal statistics is presented and compared with theoretical predictions.

Acoustic localization method using time difference of arrival of asynchronous acoustic beacons and two-element microphone array

Acoustic localization method using time difference of arrival of asynchronous acoustic beacons and two-element microphone array

Small aperture acoustic methods to locate transients

Acoustic microphone arrays have been used in battlefield environments to detect and locate continuous wave targets like helicopters and ground vehicles, and for transient events like gunshots, mortars, rockets and explosions. Depending on the application, source bandwidth, propagation distance, and required localization accuracy, these arrays can vary their sensor separation greatly. Unattended ground sensors, manned- and unmanned-platforms, and Soldier-worn systems can all benefit from very small apertures if performance can be maintained. A commercially available acoustic particle velocity sensor, approximately one-half an inch in diameter, showed good transient localization at a field experiment. Data will also be presented from a small cluster-array of cardioid microphones.

Statistical characterization of sound propagation along near-vertical paths in a turbulent atmosphere

Most previous research on sound propagation in the atmosphere has focused on nearly horizontal propagation paths, with the sources and receivers close to the ground. Along such paths, refraction by wind and temperature gradients, and scattering of sound by small-scale turbulence, are known to be important and have been studied extensively during the past couple decades. Sound propagation from elevated sources is fundamentally different because the atmospheric motions are larger, more coherent, and driven by different types of instabilities. The corresponding research is needed to address the ability of ground-based acoustic microphone arrays to detect and track elevated sound sources, as well as the ability of elevated arrays to detect and localize ground-based sources. In this paper, near-vertical sound propagation through a turbulent atmosphere is studied using approaches and methods developed in wave propagation through random media. The statistical characteristics of sound signals for near-vertical propagation such as the log-amplitude and phase fluctuations, angle-of-arrival variance, transverse and longitudinal spatial coherence, and temporal and frequency coherence are calculated and analyzed. The results obtained are compared with those for near-horizontal sound propagation.

A Novel LEACH Based Protocol for Distributed Wireless Sensor Network

A sensor node, also known as a mote (chiefly in North America), is a node in a sensor network that is capable of performing some processing, gathering sensory information and communicating with other connected nodes in the network. A mote is a node but a node is not always a mote. Each sensor node has a microprocessor and a little amount of memory. Also every sensor node is outfitted with one or more sensing devices such as acoustic sensors, microphone arrays, video cameras, infrared, seismic or magnetic sensors. But it is difficult to replace the deceased batteries of the sensor nodes. A distinctive sensor node consumes a great deal of its energy during wireless communication. This research work suggests the development of a well evaluated distributed clustering scheme for dense wireless sensor network fields, which gives improved performance over the existing clustering algorithm LEACH. The two thrashing concepts behind the proposed scheme are the hierarchical distributed clustering mechanism and the concept of threshold. Energy utilization is appreciably reduced, thereby greatly prolonging the lifetime of the sensor nodes.

Evaluation of Quenching Methods for the Purpose of Acoustic Data Collection

Using data pertaining to the audible emission of processes has become a growing area of research in recent years. This principle has been applied to the monitoring of the heat treatment process during quenching. This work highlights the importance of a proper testing methodology when collecting such data. The primary purpose of this research paper is to compare and contrast three different methodologies for controlling the experimental process and limiting variation. The first method is manual quenching, the second method automates the process by lowering the sample into the quenching medium, and the third method automates the process by raising the quenching medium container while the sample to be quenched remains fixed. In each of these methods, a spherical acoustic microphone array was used as a beam former directed at the location in which the sample entered the quenching medium. The comparisons in this work indicate that the third option yields the most consistent and repeatable results.

Structural health monitoring of wind turbine blades using acoustic microphone array

This article proposes a non-contacting measurement technique based on acoustic monitoring to detect cracks or damage within a structure by observing sound radiation using a single microphone or a beamforming array. The technique works by mounting an audio speaker inside a hollow structure, such as a wind turbine blade, and observing the sound radiated from the blade to identify damage. The primary hypothesis for this structural damage detection technique is that the structural damage (cracks, edge splits, holes, etc.) on the surface results in changes in the sound radiation characteristics of the structure. Preliminary measurements to validate the methodology were carried out on a section of a wind turbine blade containing different sized holes and cracks. An acoustic microphone array with 62 microphones was used to measure the sound radiated from the structure when an audio speaker generating random noise was placed inside a cavity emulating a wind turbine blade. A phased array beamforming technique and CLEAN-based subtraction of point spread function from a reference were employed to locate the different damage types on the test structures. The same experiment was repeated using a commercially available 48-channel acoustic ring array to compare the test results. It was shown that both the acoustic beamforming and the CLEAN-based subtraction of point spread function from reference techniques can identify the damage in the test structures with sufficiently high fidelity.

누설영역 분석을 이용한 배관 증기누설 위치 추정 방법

플랜트 배관의 누설감시 시스템은 누설 유무 판단뿐만 아니라 누설의 위치를 신속히 파악하는 것 또한 매우 중요하다. 플랜트 배관의 누설 검출 방법에는 주로 AE(acoustic emission)센서, 마이크로폰어레이 그리고 카메라 영상을 이용한 방법들이 있다. 최근 광역감시 및 원거리감시의 이점이 있는 카메라 영상을 이용한 방법에 대한 연구가 진행되어 왔다. 하지만 기존 카메라 영상을 이용한 방법들은 누설 유무와 대략적인 누설의 위치를 판단하고 있으나 누설이 시작되는 정확한 위치 추정에 대한 연구는 아직 미흡한 상태이다. 따라서 본 논문에서는 카메라를 이용한 누설 검출 방법을 이용해 누설영역을 산출하고 누설 검출 결과를 분석하여 누설 위치를 추정하는 방법을 제안하였으며 실험을 통하여 성능을 평가하였다. It is important to have a pipeline leak-detection system that determines the presence of a leak and quickly identifies its location. Current leak detection methods use a acoustic emission sensors, microphone arrays, and camera images. Recently, many researchers have been focusing on using cameras for detecting leaks. The advantage of this method is that it can survey a wide area and monitor a pipeline over a long distance. However, conventional methods using camera monitoring are unable to target an exact leak location. In this paper, we propose a method of detecting leak locations using leak-detection results combined with multi-frame analysis. The proposed method is verified by experiment.

Extending bioacoustic monitoring of birds aloft through flight call localization with a three‐dimensional microphone array

Bioacoustic localization of bird vocalizations provides unattended observations of the location of calling individuals in many field applications. While this technique has been successful in monitoring terrestrial distributions of calling birds, no published study has applied these methods to migrating birds in flight. The value of nocturnal flight call recordings can increase with the addition of three‐dimensional position retrievals, which can be achieved with adjustments to existing localization techniques. Using the time difference of arrival method, we have developed a proof‐of‐concept acoustic microphone array that allows the three‐dimensional positioning of calls within the airspace. Our array consists of six microphones, mounted in pairs at the top and bottom of three 10‐m poles, arranged in an equilateral triangle with sides of 20 m. The microphone array was designed using readily available components and costs less than $2,000 USD to build and deploy. We validate this technique using a kite‐lofted GPS and speaker package, and obtain 60.1% of vertical retrievals within the accuracy of the GPS measurements (±5 m) and 80.4% of vertical retrievals within ±10 m. The mean Euclidian distance between the acoustic retrievals of flight calls and the GPS truth was 9.6 m. Identification and localization of nocturnal flight calls have the potential to provide species‐specific spatial characterizations of bird migration within the airspace. Even with the inexpensive equipment used in this trial, low‐altitude applications such as surveillance around wind farms or oil platforms can benefit from the three‐dimensional retrievals provided by this technique.

Evaluation of Loudspeaker-Based Virtual Sound Environments for Testing Directional Hearing Aids.

Assessments of hearing aid (HA) benefits in the laboratory often do not accurately reflect real-life experience. This may be improved by employing loudspeaker-based virtual sound environments (VSEs) that provide more realistic acoustic scenarios. It is unclear how far the limited accuracy of these VSEs influences measures of subjective performance. Verify two common methods for creating VSEs that are to be used for assessing HA outcomes. A cocktail-party scene was created inside a meeting room and then reproduced with a 41-channel loudspeaker array inside an anechoic chamber. The reproduced scenes were created either by using room acoustic modeling techniques or microphone array recordings. Participants were 18 listeners with a symmetrical, sloping, mild-to-moderate hearing loss, aged between 66 and 78 yr (mean = 73.8 yr). The accuracy of the two VSEs was assessed by comparing the subjective performance measured with two-directional HA algorithms inside all three acoustic environments. The performance was evaluated by using a speech intelligibility test and an acceptable noise level task. The general behavior of the subjective performance seen in the real environment was preserved in the two VSEs for both directional HA algorithms. However, the estimated directional benefits were slightly reduced in the model-based VSE, and further reduced in the recording-based VSE. It can be concluded that the considered VSEs can be used for testing directional HAs, but the provided sensitivity is reduced when compared to a real environment. This can result in an underestimation of the provided directional benefit. However, this minor limitation may be easily outweighed by the high realism of the acoustic scenes that these VSEs can generate, which may result in HA outcome measures with a significantly higher ecological relevance than provided by measures commonly performed in the laboratory or clinic.

Investigation of coprime scattering arrays as sparse sound diffusers

Number-theoretic coprime sparse samplers have recently sparked research activities in the fields of signal processing and acoustics. The concept of coprime sparse sensing has been successfully implemented and experimentally tested in form of acoustic sparse microphone arrays, as shown in the publication [D. Bush and N. Xiang, J. Acoust. Soc. Am. 138, 447-456 (2015)]. The current study investigates how coprime theory can be applied to scattering incident sound. It also investigates how coprime array concepts can be applied to volumetric diffusers using solid cylinders as sparse array elements. These are arranged in pairs of subarrays whose number of cylinders are two mutually prime (coprime) integers in a sparse arrangement. Coprime scatter arrays are tested experimentally as sparse sound diffusers using one-fifth scale modeling and an acoustic goniometer to investigate coprime sparse diffuser effectiveness in real world applications.

Benefits of Acoustic Beamforming for Solving the Cocktail Party Problem.

The benefit provided to listeners with sensorineural hearing loss (SNHL) by an acoustic beamforming microphone array was determined in a speech-on-speech masking experiment. Normal-hearing controls were tested as well. For the SNHL listeners, prescription-determined gain was applied to the stimuli, and performance using the beamformer was compared with that obtained using bilateral amplification. The listener identified speech from a target talker located straight ahead (0° azimuth) in the presence of four competing talkers that were either colocated with, or spatially separated from, the target. The stimuli were spatialized using measured impulse responses and presented via earphones. In the spatially separated masker conditions, the four maskers were arranged symmetrically around the target at ±15° and ±30° or at ±45° and ±90°. Results revealed that masked speech reception thresholds for spatially separated maskers were higher (poorer) on average for the SNHL than for the normal-hearing listeners. For most SNHL listeners in the wider masker separation condition, lower thresholds were obtained through the microphone array than through bilateral amplification. Large intersubject differences were found in both listener groups. The best masked speech reception thresholds overall were found for a hybrid condition that combined natural and beamforming listening in order to preserve localization for broadband sources.

Visualization of multiple array acoustic source localization

Transient acoustic events such as gunfire, rocket launches, and explosions can be located using triangulation with multiple lines-of-bearing (LOBs) generated by distributed acoustic microphone arrays. The Army has fielded diverse sound localization and ranging systems that work well in open field environments, but suffer reduced performance in urban environments where echoes, multipath, diffraction, and blockages modify both the signatures and the propagation path. This demonstration will use light projected through a water basin to a screen to show traveling waves (ripple diffraction patterns) from transient events and how those wavefronts pass differently across the distributed array locations. The observers will gain an understanding of how multiple microphone elements in a small cluster of microphones (an array) can derive time-difference-of-arrival (TDOA) estimates to create array LOBs, as well as an introduction to triangulation through multiple distributed array LOBs. Objects simulating walls and buildings will be placed in the basin to demonstrate how complex waveforms and propagation paths can decrease the accuracy of acoustic localization systems.

Elephant Localization and Direction of Arrival Estimation using Acoustic Sensor Network Based on Error Rectification Methods

Direction of Arrival Estimation and monitoring the animals is one of the crucial examine focuses in our Acoustic Sensor Network. Using differential hyperbolic circular array the elephant vocalization Direction of Arrival is estimated with various external factors affecting Non-Line of Sight areas. In our experimental analysis each acoustic microphone array are seperated by 0.5M (mts) and circularly sensed the acoustic signal by 3 Kms and each sensor node deployed circularly 360o deg by TOP, BOTTOM, LEFT, RIGHT hyperbolic arrangement. The experimental results are carried out by MATLAB WAVE tool 8.1 and anaysed the overall accuracy of Direction of Arrival estimation for real time (96%) and simulated data 92% accuracy. The sensor hardware circuit audio recording and playback using Atmega Microcontroller Schematic Arduino On-Board Interfaces are supported for recording elephant signals are illustrated with its pin diagrams in the following chapters.