Статті в журналах з теми "Antennes de microphones"

We present a new development of microstrip antenna structure combining a simple circular structure with a ring antenna structure as the parasitic element to improve the antenna gain and bandwidth for 5G mobile application. The proposed antenna was fed by a 50Ω microstrip feeding line due to its advantages in performance. The antenna was designed and simulated using a single substrate with double layered copper (top and bottom) with the radiating patch on the top layer and full ground on the bottom layer of the same substrate. Three antennas have been designed namely; design1, design2 and design3 to complete the research works.The antennas ware simulated and optimized at 18 GHz using Computer Simulation Technology (CST) with permittivity, r = 2.2 and thickness, h = 1.57mm on low-loss material Roger RT-Duroid 5880 substrate. The antennas ware reasonably well matched at their corresponding frequency of operations. The simulation and measurement results have shown that the antenna works well. The simulation results have shown that the three antennas works well at the selected frequency. The final simulated antenna for design1, design2 and design3 has been fabricated to measure the performance and also to validate the simulation result with the measurement result. The measurement data for antenna design1, design2 and design3 shows frequency shift of 3% from the simulation result. The final protype of design3 gives 6.6dB gain, -14.51dB return loss, 180MHz bandwidth, and antenna efficiency of 53.9%. All three antennas ware measured using Vector network analyzer (VNA) and Anechoic chamber.

In the late 1970's and early 1980's, Jing-Yau Chung along with Joseph Pope published several external General Motors reports on the then novel measurement of sound intensity (SI) using the two-microphone, cross-spectral method. Application of this measurement method was then extended to sound intensity measurements in flow. Through component wind tunnel measurements, it was determined that the intensity of noise sources could be accurately measured up to a level of 15 dB below the sound pressure level generated by flow noise on microphones. An initial application of this method was to the identification of noise sources alongside rolling truck tires. It was then extended to the measurement of the aerodynamic noise generated by protrusions added to automotive vehicle designs. These included items such as outside rearview mirrors, windshield wipers, A-pillar offsets, grille whistles, roof racks, underbodies, and fixed-mast radio antennas. Many of these could be applied on the early full-size clay models or other mock-ups as well as actual vehicles. An application of sound intensity was the development of the straked antenna design leading to a GM Defensive Patent and its now universal application to virtually all vehicles with simple fixed-mast antennas. The development of this design is highlighted along with the background on the application of sound intensity to measurements in air flow.

This paper introduces passive wireless telemetry based operation for high frequency acoustic sensors. The focus is on the development, fabrication, and evaluation of wireless, batteryless SAW-IDT MEMS microphones for biomedical applications. Due to the absence of batteries, the developed sensors are small and as a result of the batch manufacturing strategy are inexpensive which enables their utilization as disposable sensors. A pulse modulated surface acoustic wave interdigital transducer (SAW-IDT) based sensing strategy has been formulated. The sensing strategy relies on detecting the ac component of the acoustic pressure signal only and does not require calibration. The proposed sensing strategy has been successfully implemented on an in-house fabricated SAW-IDT sensor and a variable capacitor which mimics the impedance change of a capacitive microphone. Wireless telemetry distances of up to 5 centimeters have been achieved. A silicon MEMS microphone which will be used with the SAW-IDT device is being microfabricated and tested. The complete passive wireless sensor package will include the MEMS microphone wire-bonded on the SAW substrate and interrogated through an on-board antenna. This work on acoustic sensors breaks new ground by introducing high frequency (i.e., audio frequencies) sensor measurement utilizing SAW-IDT sensors. The developed sensors can be used for wireless monitoring of body sounds in a number of different applications, including monitoring breathing sounds in apnea patients, monitoring chest sounds after cardiac surgery, and for feedback sensing in compression (HFCC) vests used for respiratory ventilation. Another promising application is monitoring chest sounds in neonatal care units where the miniature sensors will minimize discomfort for the newborns.

ABSTRACT Acoustic communications often have limited data rates because of the intrinsically low frequencies. Exploring new spatial modes to increase data bandwidth at fixed frequency is a possible solution to this problem. Here, we demonstrate acoustic wave chirality transmission between two reciprocal metamaterial vortex wave antennas, generating and sensing transmitted acoustic wave chirality through the sub-wavelength geometry of the system. By adding an acoustic leaky wave surface to a ring resonator waveguide, acoustic vortex waves with positive or negative integer mode chirality are independently radiated and detected using a small number of microphones. Through computational simulation and experimental verification, using three-dimensional printed waveguides, we show that the vortex mode chirality can be transferred between two opposing acoustic vortex wave antennas across a small unguided air gap. We also show that emission into an external waveguide can provide long distance data transmission. This demonstrates the first use of metamaterial vortex wave antennas as chiral, mode multi-channel data transceivers.

In recent years, the current technological improvements of Unmanned Aerial Vehicles (UAV) have allowed more and more efficient use for applications ranging from simple amateur shooting to more professional tasks. Being handy, drones can easily fly near sensitive sites, such as power plants, airports or ministries. It is therefore necessary to develop systems able to keep watch such sites. However, the size and the composition of these devices make optical or electromagnetic systems inefficient for their detection. This study proposes an alternative exploiting the sound wave emitted by their motorization and / or their aerodynamic whistling. For this, an acoustic antenna with few microphones was sized to be sensitive to frequencies emitted by a drone. Firstly, an experimental analysis on the noise made by a drone was carried out. The results allowed us to settle the geometry of the antenna in order to process localization. Two methods of location are used. The first is based on an energy approach providing the acoustic field reconstruction in all directions of space. The second estimates the position of the source by inverting a system exploiting the arrival time differences of the acoustic wave between different pairs of microphones. Numerical simulations, supported by a measurement campaign, make it possible to highlight the performance of the methods used.

This paper is devoted to the sensor selection problem. A broadband receiver beamforming working in a near-field is considered. The system response should be as close as possible to the desired one, which is optimized in the sense of L2 norm. The problem considered is at least NP-hard. Therefore, the branch-and-bound algorithm is developed to solve the problem. The proposed approach is universal and can be applied not only to microphone arrays but also to antenna arrays; that is, the methodology for the generation of consecutive solutions can be applied to different types of sensor selection problems. Next, for a larger microphone array, an efficient metaheuristic algorithm is constructed. The algorithm implemented is a hybrid genetic algorithm based on the ITÖ process. Numerical experiments show that the proposed approach can be successfully applied to the sensor selection problem.

The measurement of the absorption coefficient of acoustic materials is usually performed in an impedance tube under normal incidence on a small sample, or in a reverberant room under diffuse field incidence on a large sample of material. Both methods are prone to well-documented experimental limitations and errors. The approach proposed here uses a virtual source antenna (a point source moved at successive positions) over a material sample typically 1 to 4 m2 in size, and a fixed microphone pair directly above the material surface. Several methods have been tested to reconstruct the absorption coefficient under oblique plane wave or diffuse field incidence. Among these, the inversion of the Allard propagation model over an absorbing plane, in order to extract the material properties (complex wavenumber and density) from measured microphone transfer functions, is presented here. Absorption coefficients are shown for various acoustic materials.

Acoustic cameras are used to investigate the origin of a noise and localize it on video for a couple of decades. This was made possible by applying beamforming techniques to the acoustic signals simultaneously acquired by a microphone array. The number of scientists working on improving the efficiency and accuracy of this technique increased over the years, leading to the design and production of different shapes for the antenna and microphone array. Moreover, in the last years many different algorithms for beamforming techniques have been published to improve the original "Delay and Sum" method. This field is evolving rapidly and, unfortunately, there is no clear view on the advantages of one method over another, both from a theoretical and a practical point of view. This work shows the different results obtained by different algorithms when applied to the same input acoustic signals, i.e., they can localize the noise source in different points of the screen. The input signals were acquired with acoustic camera measurements to investigate port noise, a topic that has been neglected for too long and on which only few studies have been carried out. The various sound sources acting on ships' pass-by and the predominant emitters in a multi-source environment have therefore been localized using the different algorithms.

O presente artigo tem como objetivo analisar os objetos de comunicação e escolares no Sistema Educativo Radiofônico de Bragança, Estado do Pará, (1957-1977). A tessitura metodológica é constituída pela abordagem da Nova História Cultural que se estabelece enquanto campo teórico e metodológico das representações. Diante disso, constatou-se que os objetos de comunicação e escolares localizavam-se em diferentes instituições: o microfone foi identificado na Rádio Educadora; o gravador foi encontrado no Escritório Central do SERB; as antenas e os transmissores foram identificados nas casas dos transmissores. Conclui-se que esses objetos são constituidores dos sentidos da educomunicação no cerne desta instituição educativa.Palavras-chave: Objetos de comunicação e escolares; Sistema Educativo Radiofônico de Bragança – PA; Sentidos da Educomunicação.COMMUNICATION AND SCHOOL OBJECTS IN THE RADIOPHONIC EDUCATION SYSTEM IN BRAGANÇA - PARÁ (1957-1977)AbstractThe present study aims to analyze the communication and school objects in the Bragança Radiophonic Educational System, State of Pará, (1957-1977). The methodological composition is constituted by the Cultural History New approach that is established as a theoretical and methodological field of the representations. Therefore, the present study was found that communication and school objects were located in different institutions: the microphone was on the Educator Radio; the recorder was in the main office of the SERB, the antennas, and transmitters were in the homes of the transmitters. It is concluded that these objects are established by the edu-communication way based on this educational institution.Keywords: Communication and school objects; Radiophonic education system in Bragança – PA; Educommunication ways.COMUNICACIÓN Y OBJETOS ESCOLARES EN EL SISTEMA EDUCATIVO DE RADIO BRAGANÇA - PARÁ (1957-1977)ResumenEste artículo tiene como objetivo analizar la comunicación y los objetos escolares en el Sistema Educativo Radiofónico Bragança, Estado de Pará, (1957-1977). El tejido metodológico está constituido por el enfoque de la Nueva Historia Cultural que se establece como campo teórico y metodológico de las representaciones. Ante esto, se encontró que la comunicación y los objetos escolares estaban ubicados en diferentes instituciones: el micrófono fue identificado en Radio Educadora; la grabadora fue encontrada en la sede de SERB; Se han identificado antenas y transmisores en casas de transmisores. Se concluye que estos objetos constituyen los significados de la educomunicación en el corazón de esta institución educativa.Palabras clave: comunicación y objetos escolares; Sistema de educación radiofónica Bragança - PA; Direcciones de Educommunication.

Acoustic leaky-wave antennas (ALWAs) have demonstrated the capacity to steer directive sound waves in frequency-dependent directions, due to the inherent dispersive radiation characteristic of leaky modes. Compared to more conventional uniform linear array (ULA) acoustic traducers for electronic beam steering (which rely on multiple sensors), the ALWA allows for single microphone operation. Thus, ALWAs offer a direct mechanism to scan a directive acoustic beam in the angular space by simply sweeping the operating frequency of the acoustic signal, which envisions cost-efficient single-transducer direction finders for SONAR applications. In this paper, we study for the first time some important features of an ALWA for acoustic underwater Direction-of-Arrival (DoA) estimation applications. First, we report for the first time on the necessity to shape the radiated ALWA beams in both far- and near-field zones to improve the DoA estimation performance, following similar techniques recently applied for low-cost frequency-scanned direction-finding radars based on LWAs. Furthermore, the capacity to reduce the Side Lobe Level (SLL) has been analyzed in order to improve performance, demonstrating aperture tapering techniques to the ALWA for the first time. These acoustic behaviour aspects have a considerable interest in real applications of ALWA in innovative SONAR systems for underwater scenarios.

A semi-implantable middle ear electromagnetic hearing device (SIMEHD) is proposed for limited clinical trial in adult patients to evaluate the implantable hearing device for moderate to severe sensorineural hearing loss. Food and Drug Administration (FDA) investigational device exemption (IDE) approval has been granted (May 1996) for clinical trials. The implant unit has been evaluated acutely and chronically in animals (cats) with excellent results. Five cats undergoing chronic implantation were allowed to survive an average of 9.6 months, showing that the SIMEHD is biocompatible, functional and without untoward complications. All implant units recovered from the cats were functional, except for wire breakage of the internal antenna. A new antenna was redesigned for human implantation. The SIMEHD system consists of an external and internal unit. The external unit consists of a microphone, audio amplifier, modulator, radio frequency (RF) amplifier, antenna and battery. The internal unit is composed of a receiving antenna, hybrid electronic circuit, air core driving coil, and a target magnet cemented to the incus. All materials in contact with the body are biocompatible and expected to survive indefinitely. The implant unit is miniaturized and manufactured with existing fabrication technology by our industrial collaborator, Wilson Greatbatch, Ltd. The specific aims and major tasks of the proposed research are: a) to evaluate reliability, safety and efficacy of the SIMEHD system in a selected group of patients diagnosed with sensorineural hearing loss, due mainly to presbycusis or aging of the inner ear; and b) to obtain objective and subjective evaluation of audiologic and psychoacoustic performance as compared to the acoustic hearing aid. This paper describes the design, illustrates the actual device (newest prototype) and details the technique for surgical implantation in the attic and mastoid antrum in humans.

The MCU has the smaller volume, low cost, face control, antijamming ability strong and so on merits, GPRS is based on the GSM development foundation in data traffic. one kind of GPRS system Has been designed by using MCU STC12C5A60S2, it including correspondence transformation connection, SIM300 module, MCU, display circuit, keyboard electric circuit, RS232 exterior serial communication connection and so on. The related hardware welding on the PCB, the software programming after-burning writes in the MCU, inserts the liquid crystal display monitor and the SIM card, joins the receiver and the microphone, connects the good GPRS antenna. On the electricity, the establishment correspondence transformation connection, may realize the close-down, the dial and the answering telephone, transmits and receives the SMS, to receive and dispatch E-mail, carries on the Internet to glance over and so on, indicated that has achieved the design requirements.

A new compact multiband PIFA (Planar Inverted-F Antenna) for mobile handset is proposed in this article. The proposed PIFA has a simple geometry with four slots integrated in the radiating patch and ground plane. The PIFA occupies a small volume of 51 × 14 × 7.2 mm3 and is placed on the top portion of mobile phone. The optimized PIFA is worked in the 790 MHz band (737–831 MHz), the 1870 MHz band (1794–1977 MHz), the 2550 MHz band (2507–2615 MHz), and the 3400 MHz band (3341–3545 MHz), to cover LTE700, LTE800, DCS1800, PCS1900, LTE1800, LTE1900, LTE2500, and WIMAX3400 bands. Each of the four operating bands can be controlled independently by the variation of a single parameter of the proposed design, with a wide control range. An omnidirectional radiation pattern to each resonant frequency is obtained with a maximum gain of 2.15 dBi at 790 MHz, 3.99 dBi at 1870 MHz, 4.57 dBi at 2550 MHz, and 6.43 dBi at 3400 MHz. The proposed PIFA is studied in the free space and in the presence of other mobile phone components such as the battery, LCD (liquid crystal display), camera, microphone, speaker, buttons, and a plastic housing. The distribution of specific absorption rate for both European and American standards for each operating band and at various distances between the antenna and the human head is also studied.

The anechoic chamber is closely related as a device for precisely measuring various acoustic characteristics. Anechoic chambers room conditions controlled to produce a sound field-free space. This study focused on testing various commercial wedges such as Eckel, diamond, pyramidal, and oblique pyramidal. The test was done by varying the elevation of an incident angle at 0°-85° with a stepping distance is 5°. This study is analyzed at 1-3 GHz frequency. This research was conducted based on a computational analysis using the finite element method on electromagnetic wave physics interfaces using COMSOL Multiphysics. The results show that, in general, pyramidal has the best performance. These results are assessed from the stability of absorption performance, the Eckel model obtains -66.6 dB at 1 GHz frequency but on another frequency tests with drastic performance fluctuations. In general, a pyramidal model can be an ideal absorber for anechoic applications because it provides good absorption performance for near normal and normal incidence angles. The results of the design and testing of the wedges model for anechoic are expected to be references in designing the optimal anechoic chamber room. Furthermore, it can contribute positively to tuning acoustic instruments such as microphones or reducing the antenna measurement error.

Continuous exposure to urban noise has been found to be one of the major threats to citizens’ health. In this regard, several organizations are devoting huge efforts to designing new in-field systems to identify the acoustic sources of these threats to protect those citizens at risk. Typically, these prototype systems are composed of expensive components that limit their large-scale deployment and thus reduce the scope of their measurements. This paper aims to present a highly scalable low-cost distributed infrastructure that features a ubiquitous acoustic sensor network to monitor urban sounds. It takes advantage of (1) low-cost microphones deployed in a redundant topology to improve their individual performance when identifying the sound source, (2) a deep-learning algorithm for sound recognition, (3) a distributed data-processing middleware to reach consensus on the sound identification, and (4) a custom planar antenna with an almost isotropic radiation pattern for the proper node communication. This enables practitioners to acoustically populate urban spaces and provide a reliable view of noises occurring in real time. The city of Barcelona (Spain) and the UrbanSound8K dataset have been selected to analytically validate the proposed approach. Results obtained in laboratory tests endorse the feasibility of this proposal.

Abstract. The PEACH project (Projet en Electricité Atmosphérique pour la Campagne HyMeX – the Atmospheric Electricity Project of the HyMeX Program) is the atmospheric electricity component of the Hydrology cycle in the Mediterranean Experiment (HyMeX) experiment and is dedicated to the observation of both lightning activity and electrical state of continental and maritime thunderstorms in the area of the Mediterranean Sea. During the HyMeX SOP1 (Special Observation Period) from 5 September to 6 November 2012, four European operational lightning locating systems (ATDnet, EUCLID, LINET, ZEUS) and the HyMeX lightning mapping array network (HyLMA) were used to locate and characterize the lightning activity over the northwestern Mediterranean at flash, storm and regional scales. Additional research instruments like slow antennas, video cameras, microbarometer and microphone arrays were also operated. All these observations in conjunction with operational/research ground-based and airborne radars, rain gauges and in situ microphysical records are aimed at characterizing and understanding electrically active and highly precipitating events over southeastern France that often lead to severe flash floods. Simulations performed with cloud resolving models like Meso-NH and Weather Research and Forecasting are used to interpret the results and to investigate further the links between dynamics, microphysics, electrification and lightning occurrence. Herein we present an overview of the PEACH project and its different instruments. Examples are discussed to illustrate the comprehensive and unique lightning data set, from radio frequency to acoustics, collected during the SOP1 for lightning phenomenology understanding, instrumentation validation, storm characterization and modeling.

Our contribution in this work is to detect, localize and quantify the noise sources radiated by a spur gear transmission mechanism. The imaging technique is used; it is based on the acoustic inverse frequency response function (IFRF). The IFRF is based on the inversion of the transfer matrix built between the source points represented by their complex source strengths and listening points represented by the complex pressures measured by the hologram. The measurements were performed in a semi-anechoic room where the floor is concrete and the walls are covered with glass wool. The complex acoustic pressures are measured by an antenna with microphones regularly spaced; it is placed above the noisy mechanism. The reconstruction problem is therefore an inverse problem and is said ill-posed; thus, regularizations are needed to stabilize and to find the best solutions. As regularization technique, the Tikhonov method is applied and the regularization parameters are chosen according to the L-curve method. The goal is to reconstruct as accurately as possible the acoustic field radiated by the transmission mechanism on a fictive and tangent plane to the noisy mechanism considered open and sometimes closed. The results obtained showed that the sources were located with good approximation. The IFRF method is able to reconstruct the sound sources responsible for the noise radiated by the mechanism without any a priori information of the sources distribution, and the visualization of spatial acoustic fields facilitate the understanding of the complex phenomena of radiation.

Radiated noise is a major topic of interest regarding the brake squeal phenomenon as it is directly linked to the noise generated which can be potentially detrimental to user comfort and perception. However, very few studies offer in-depth and comprehensive insight into the analysis and understanding of acoustic noise during squeal events. This study is intended to provide an original contribution to this issue by investigating acoustic phenomena occurring during the squeal phenomenon via a digital antenna composed of 117 microphones. Experiments are performed on the Friction-Induced Vibration and noisE test bench at Ecole Centrale de Lyon (FIVE@ECL). The first main aim is to investigate the characteristics of the acoustic radiated field during brake squeal and more particularly to describe the evolution of the radiated field patterns per revolution of the disc system. The second major aim is to illustrate the possibility of reconstructing the radiated acoustic field everywhere in the space surrounding the brake system, leading to the construction of a robust representation of 3D acoustic patterns, providing acoustic squeal events in the physical space around the brake system. Results show that the vibratory signature remains identical during squeal event braking test. The acoustic signature of squeal noise consists mainly of a fundamental frequency and its harmonic components, with secondary lower contributions from other fundamental frequencies. The associated radiated acoustic field during squeal events are characterized by different directivities and intensities of the acoustic radiated field for each squeal frequency, with potential changes in these directivities and intensities over short times corresponding to the rotation period of the disc.

In the digital stage of world development, information is constantly expanding its facets. That is why the exchange of information is a leading component of constant change in life. Although humanity is gradually moving to the use of electronic technology, acoustic information still plays a key role in information circulation. This applies to official communication in public institutions up to the highest level, business contacts in commercial structures and private communication between people. The process of transmitting information in acoustic form has dangerous consequences. The use of appropriate devices, such as directional acoustic microphones or technical intelligence acoustic antennas, which may be outside the scope of the information activity, makes it possible to obtain unauthorized information that should not reach third parties. Therefore, the task of detecting and protecting information leakage channels, including acoustic ones, is gaining a new degree of importance every day. The protection of the premises or building, where acoustic information regularly circulates, provides a set of organizational and technical measures and means of protection of information circulation, taking into account the peculiarities of the location and arrangement of the object. This study involves the study of the dependence of the level of the acoustic signal on ways to prevent leakage of information through the acoustic channel, which includes vibration noise by means of technical protection and coverage of improvised materials (shielding) of enclosing structures of information activities (OID). The experiment determines the degree of influence of density, sound-absorbing properties of materials and their combinations on acoustic oscillations, the source of which is in the OID. The object of the study was a basic room, where the enclosing structures are walls with windows and doors, ceiling and floor. It is also worth noting that the acoustic signal measurements were not performed in complete silence, which directly affected the accuracy of the results. This step was taken in order to best reproduce the conditions in which criminals often work.

Attini ants (Hymenoptera, Formicidae, Myrmicinae) have great diversity in exploiting food resources. However, little is known about the mycophagy involving Agaricales fungi (Basidiomycota, Agaricomycetes). Moreover, these associations are of paramount importance in riparian zones, as the interaction among soil, fauna and flora is fundamental to the maintenance of these environments. Thus, the aim of this study was to describe cases of mycophagy between ants and fungi in order to understand how these associations occur in riparian zones. To this, collections were made between 2021-2022 in the valleys of the Rio Vacacaí, Rio dos Sinos and Rio Pardo in the state of Rio Grande do Sul, Brazil. The samples were analyzed for characters macro and microscopic and identified taxonomically. Mycophagy activities of six species of ants worker were cataloged, among them Acromyrmex niger, Acromyrmex versicolor, Tranopelta gilva, Tranopelta subterranea, Pheidole flavens and Mycetosoritis hartmanni, which included in their diet the mushrooms Agaricus rufoaurantiacus, Macrocybe titans, Agrocybe underwoodii, Dactylosporina steffenii, Lepiota micropholis and Neopaxillus echinospermus, respectively. The observed interactions demonstrate the dispersal of fungal spores through ant body structures, such as legs, antennae, thorax and abdomen; basidiomata as aliment source, such as pileus, lamellae and stipe; and generalized and specialized levels of predation on various fungi structures. Our results demonstrate unprecedented mycophagous relationships and show that Agaricales fungi can be considered a food source for Attini in riparian zones in Brazil south.

Abstract. The PEACH (Projet en Electricité Atmosphérique pour la Campagne HyMeX – the Atmospheric Electricity Project of HyMeX Program) project is the Atmospheric Electricity component of the HyMeX (Hydrology cycle in the Mediterranean Experiment) experiment and is dedicated to the observation of both lightning activity and electrical state of continental and maritime thunderstorms in the area of the Mediterranean Sea. During the HyMeX SOP1 (Special Observation Period; 5 September–6 November 2012), four European Operational Lightning Locating Systems (OLLSs) (ATDNET, EUCLID, LINET, ZEUS) and the HyMeX Lightning Mapping Array network (HyLMA) were used to locate and characterize the lightning activity over the Southeastern Mediterranean at flash, storm and regional scales. Additional research instruments like slow antennas, video cameras, micro-barometer and microphone arrays were also operated. All these observations in conjunction with operational/research ground-based and airborne radars, rain gauges and in situ microphysical records aimed at characterizing and understanding electrically active and highly precipitating events over Southeastern France that often lead to severe flash floods. Simulations performed with Cloud Resolving Models like Meso-NH and WRF are used to interpret the results and to investigate further the links between dynamics, microphysics, electrification and lightning occurrence. A description of the different instruments deployed during the field campaign as well as the available datasets is given first. Examples of concurrent observations from radio frequency to acoustic for regular and atypical lightning flashes are then presented showing a rather comprehensive description of lightning flashes available from the SOP1 records. Then examples of storms recorded during HyMeX SOP1 over Southeastern France are briefly described to highlight the unique and rich dataset collected. Finally the next steps of the work required for the delivery of reliable lightning-derived products to the HyMeX community are discussed.

AbstractState-of-the-art physics experiments require high-resolution, low-noise, and low-threshold detectors to achieve competitive scientific results. However, experimental environments invariably introduce sources of noise, such as electrical interference or microphonics. The sources of this environmental noise can often be monitored by adding specially designed “auxiliary devices” (e.g. microphones, accelerometers, seismometers, magnetometers, and antennae). A model can then be constructed to predict the detector noise based on the auxiliary device information, which can then be subtracted from the true detector signal. Here, we present a multivariate noise cancellation algorithm which can be used in a variety of settings to improve the performance of detectors using multiple auxiliary devices. To validate this approach, we apply it to simulated data to remove noise due to electromagnetic interference and microphonic vibrations. We then employ the algorithm to a cryogenic light detector in the laboratory and show an improvement in the detector performance. Finally, we motivate the use of nonlinear terms to better model vibrational contributions to the noise in thermal detectors. We show a further improvement in the performance of a particular channel of the CUORE detector when using the nonlinear algorithm in combination with optimal filtering techniques.

AbstractMetasurfaces are artificial materials that can provide properties not readily available in nature for the interaction with acoustic, elastodynamic, or electromagnetic waves. In Electromagnetics, metasurfaces allow particular functionalities to antennas, which in turn lately have been increasingly pushed to a multiband operation. To fully exploit metasurfaces’ capabilities, the use of a metasurface reflector and a metasurface superstrate surrounding a radiating element in multiband antennas is interesting. However, such topology generally creates multiple reflections inside the formed cavity, known as Fabry–Pérot resonances. Here we show that one should tame this phenomenon to use two parallel metasurfaces surrounding a planar radiating element. We present the conditions to obtain directive, multiband antennas under such circumstances. The concepts are validated with a compact device for 5G/4G/Wi-Fi 2.4/5/6E performing a beam steering in the 5G without disturbing the radiation patterns of the other bands. This device demonstrates that the functionalities of two metasurfaces may be exploited in a single design if the presented conditions are respected. We also anticipate our work to be a starting point for other studies in the wave domain. For example, compact, multiband, beam-steerable microphones or sonar transducers with two parallel metasurfaces could be investigated in the future.

Abstract Terahertz (THz) wave plays important roles in the research of material properties, the non-invasive human security check and the next generation wireless communication. The progress of the scientific and technological applications of THz wave is strongly dependent on the improvement of THz detectors. Here a novel THz wave detection scheme is proposed in which the THz radiation is detected by an audible microphone based on the photo-thermo-acoustic (PTA) effect in graphene foam. Thanks to the room-temperature broadband electromagnetic absorption characteristics of graphene foam and the fast heat transfer between graphene foam and ambient air, this detection method not only inherits the advantages of the photo-thermal THz detector such as room-temperature and full bandwidth, but also has a response time 3 orders of magnitude faster than the photo-thermal detector. Besides, no micro-antenna/electrode is required to fabricate in the graphene foam THz detector which greatly simplifies the detector design and decreases the fabrication cost. It concludes that the room-temperature, full-bandwidth, fast-speed (≥10 kHz), and easy-to-fabricate THz detector developed in this work has superior comprehensive performances among both the commercial THz detectors and the detectors recently developed in laboratory.

AbstractWith the growth of modern turbofan engines, their integration under the wing becomes challenging and induces aerodynamic and acoustic interactions between the jet exhaust and the airframe. Jet noise reduction techniques have been widely studied over the past decades but their efficiency has still to be demonstrated once installed. The present lab-scale jet experiments at Mach 0.6 compare the noise radiated by beveled and rectangular installed nozzles to circular ones on a quarter-sphere radiation map using a microphone antenna. For all radiation angles, modified nozzles show an amplitude decrease of the jet-plate interaction tones of the noise spectra attributed to a strong coupling between the jet shear layers and the sound scattering at the plate trailing edge. Beveled nozzles achieve a noise reduction for all radiation angles with a maximum decrease up to 2 dB at receiver locations perpendicular to the plate. While rectangular nozzles show a similar behavior, a sound increase is observed for listeners parallel to the plate when the height-to-width ratio is small.

The article considers the classical scheme of the broadcast news studio and the principle of operation of the television broadcasting system on the example of the standard of the international digital television system, which is the reference model of terrestrial digital television transmission. The structural scheme of the broadcast news studio is given, the functions of each block of the studio and the principle of their work are described. The diagram of the digital television system shows how the signal from the studio passes through the stages of encoding and modulation to the broadcasting antenna, and then the demodulated and decoded TV signal appears in the digital television application on the viewer's side. The interactive communication channel is also discussed in more detail. The diagram of the interactive communication channel presented in this article shows how the communication between the broadcasting company and the viewer of digital television takes place. However, given the current tendency of TV channels to move from broadcasting on digital television to online broadcasting on streaming platforms, the article considers an example of organizing an online broadcast on the YouTube platform. Using the example of equipment from the classical scheme of the broadcast studio, the selection of similar low-budget equipment for organizing a studio for online broadcasts was carried out. The list of low-budget equipment includes a video mixer, video cameras, lighting equipment and two types of microphones. The advantages and disadvantages of low-budget equipment are indicated, from which it can be concluded that low-budget equipment is not of poor quality, but is designed for a smaller number of connected equipment, so it is suitable for use in small television studios. The functions and possibilities of using the selected Blackmagic ATEM Mini Pro video mixer are considered. A scheme for organizing a live broadcast on the YouTube streaming platform using the selected equipment is presented. The low budget of the studio is substantiated by estimates and comparison with the budget of a similar educational television studio. The possibilities of remote access organizing to the workplace via VPN (Virtual Private Network) and RDC (Remote Desktop Connection) are also considered. These features allow employees to work from a remote location, not directly in the studio. The purpose of the article was to determine how does remote access delay the work of the studio and complicate the process of launching online broadcasts. Measurements of connection delay and broadcasting were carried out. According to the results of the measurements, it was concluded that both VPN and RDC insignificantly affects the connection speed of the equipment, so remote work can be equally comfortable as working directly in the studio. The difference between remote work and direct work in the studio consists of in the preliminary configuration of devices for remote connection and also remote work depends on the Internet connection entirely and light availability in the studio.

IntroductionThis short article examines contemporary artistic use of walkie-talkies across two projects: Saturday (2002) by Sabrina Raaf and Walk That Sound (2014) by Lukatoyboy. Drawing on Dominic Pettman’s notion of sonic intimacy, I argue that both artists incorporate walkie-talkies as part of their explorations of mediated wandering, and in ways that seek to capture sonic ambiances and intimacies. One thing that is striking about both these works is that they rethink what’s possible with walkie-talkies; both artists use them not just as low-tech, portable devices for one-to-one communication over distance, but also—and more strikingly—as (covert) recording equipment for capturing, while wandering, snippets of intimate conversation between passers-by and the “voice” of the surrounding environment. Both artworks strive to make the familiar strange. They prompt us to question our preconceived perceptions of, and affective engagements with, the people and places around us, to listen more attentively to the voices of others (and the “Other”), and to aurally inhabit in new ways the spaces and places we find ourselves in and routinely pass through.The walkie-talkie is an established, simple communication device, consisting of a two-way radio transceiver with a speaker and microphone (in some cases, the speaker is also used as the microphone) and an antenna (Wikipedia). Walkie-talkies are half-duplex communication devices, meaning that they use a single radio channel: only one radio on the channel can transmit at a time, but many can listen; when a user wishes to talk, they must turn off the receiver and turn on the transmitter by pressing a push-to-talk button (Wikipedia). In some models, static—known as squelch—is produced each time the push-to-talk button is depressed. The push-to-talk button is a feature of both projects: in Saturday, it transforms the walkie-talkie into a cheap, portable recorder-transmitter. In Walk That Sound, rapid fire exchanges of conversation using the push-to-talk button feature strongly.Interestingly, walkie-talkies were developed during World War Two. While they continue to be used within certain industrial settings, they are perhaps best known as a “quaint” household toy and “fun tool” (Smith). Early print ads for walkie-talkie toys marketed them as a form of both spyware for kids (with the Gabriel Toy Co. releasing a 007-themed walkie-talkie set) and as a teletechnology for communication over distance—“how thrilling to ‘speak through space!’”, states one ad (Statuv “New!”). What is noteworthy about these early ads is that they actively promote experimental use of walkie-talkies. For instance, a 1953 ad for Vibro-Matic “Space Commander” walkie-talkies casts them as media transmission devices, suggesting that, with them, one can send and receive “voice – songs – music” (Statuv “New!”). In addition, a 1962 ad for the Knight-Kit walkie-talkie imagines “you’ll find new uses for this exciting walkie-talkie every day” (Statuv “Details”). Resurgent interest in walkie-talkies has seen them also promoted more recently as intimate tools “for communication without asking permission to communicate” (“Nextel”); this is to say that they have been marketed as devices for synchronous or immediate communication that overcome the limits of asynchronous communication, such as texting, where there might be substantial delays between the sending of a message and receipt of a response. Within this context, it is not surprising that Snapchat and Instagram have also since added “walkie-talkie” features to their messaging services. The Nextel byline, emphasising “without asking permission”, also speaks to the possibilities of using walkie-talkies as rudimentary forms of spyware.Within art practice that explores mediated forms of wandering—that is, walking while using media and various “remote transmission technologies” (Duclos 233)—walkie-talkies hold appeal for a number of reasons, including their particular aesthetic qualities, such as the crackling or static sound (squelch) that one encounters when using them; their portability; their affordability; and, the fact that, while they can be operated on multiple channels, they tend to be regarded primarily as devices that permit two-way, one-to-one (and therefore intimate, if not secure) remote communication. As we will see below, however, contemporary artists, such as the aforementioned earlier advertisers, have also been very attentive to the device’s experimental possibilities. Perhaps the best known (if possibly apocryphal) example of artistic use of walkie-talkies is by the Situationist International as part of their explorations in urban wandering (a revolutionary strategy called dérive). In the Situationist text from 1960, Die Welt als Labyrinth (Anon.), there is a detailed account of how walkie-talkies were to form part of a planned dérive, which was organised by the Dutch section of the Situationist International, through the city of Amsterdam, but which never went ahead:Two groups, each containing three situationists, would dérive for three days, on foot or eventually by boat (sleeping in hotels along the way) without leaving the center of Amsterdam. By means of the walkie-talkies with which they would be equipped, these groups would remain in contact, with each other, if possible, and in any case with the radio-truck of the cartographic team, from where the director of the dérive—in this case Constant [Nieuwenhuys]—moving around so as to maintain contact, would define their routes and sometimes give instructions (it was also the director of the dérive’s responsibility to prepare experiments at certain locations and secretly arranged events.) (Anon.) This proposed dérive formed part of Situationist experiments in unitary urbanism, a process that consisted of “making different parts of the city communicate with one another.” Their ambition was to create new situations informed by, among other things, encounters and atmospheres that were registered through dérive in order to reconnect parts of the city that were separated spatially (Lefebvre quoted in Lefebvre and Ross 73). In an interview with Kristin Ross, Henri Lefebvre insists that the Situationists “did have their experiments; I didn’t participate. They used all kinds of means of communication—I don’t know when exactly they were using walkie-talkies. But I know they were used in Amsterdam and in Strasbourg” (Lefebvre quoted in Lefebvre and Ross 73). However, as Rebecca Duclos points out, such use “is, in fact, not well documented”, and “none of the more well-known reports on situationist activity […] specifically mentions the use of walkie-talkies within their descriptive narratives” (Duclos 233). In the early 2000s, walkie-talkies also figured prominently, alongside other media devices, in at least two location-based gaming projects by renowned British art collective Blast Theory, Can You See Me Now? (2001) and You Get Me (2008). In the first of these projects, participants in the game (“online players”) competed against members of Blast Theory (“runners”), tracking them through city streets via a GPS-enabled handheld computer that runners carried with them. The goal for online players was to move an avatar they created through a virtual map of the city as multiple runners “pursued their avatar’s geographical coordinates in real-time” (Leorke). As Dale Leorke explains, “Players could see the locations of the runners and other players and exchange text messages with other players” (Leorke 27), and runners could “read players’ messages and communicate directly with each other through a walkie-talkie” (28). An audio stream from these walkie-talkie conversations allowed players to eavesdrop on their pursuers (Blast Theory, Can You See Me Now?).You Get Me was similarly structured, with online players and “runners” (eight teenagers who worked with Blast Theory on the game). Remotely situated online players began the game by listening to the “personal geography” of the runners over a walkie-talkie stream (Blast Theory, You Get Me). They then selected one runner, and tracked them down by navigating their own avatar, without being caught, through a virtual version of Mile End Park in London, in pursuit of their chosen runner who was moving about the actual Mile End Park. Once their chosen runner was contacted, the player had to respond to a question that the runner posed to them. If the runner was satisfied with the player’s answer, conversation switched to “the privacy of a mobile phone” in order to converse further; if not, the player was thrown back into the game (Blast Theory, You Get Me). A key aim of Blast Theory’s work, as I have argued elsewhere (Wilken), is the fostering of interactions and fleeting intimacies between relative and complete strangers. The walkie-talkie is a key tool in both the aforementioned Blast Theory projects for facilitating these interactions and intimacies.Beyond these well-known examples, walkie-talkies have been employed in productive and exploratory ways by other artists. The focus in this article is on two specific projects: the first by US-based sound artist Sabrina Raaf, called Saturday (2002) and the second by Serbian sound designer Lukatoyboy (Luka Ivanović), titled Walk That Sound (2014). Sonic IntimaciesThe concept that gives shape and direction to the analysis of the art projects by Raaf and Lukatoyboy and their use of walkie-talkies is that of sonic intimacy. This is a concept of emerging critical interest across media and sound studies and geography (see, for example, James; Pettman; Gallagher and Prior). Sonic intimacy, as Dominic Pettman explains, is composed of two simultaneous yet opposing orientations. On the one hand, sonic intimacy involves a “turning inward, away from the wider world, to more private and personal experiences and relationships” (79). While, on the other hand, it also involves a turning outward, to seek and heed “the voice of the world” (79)—or what Pettman refers to as the “vox mundi” (66). Pettman conceives of the “vox mundi” as an “ecological voice”, whereby “all manner of creatures, agents, entities, objects, and phenomena” (79) have the opportunity to speak to us, if only we were prepared to listen to our surroundings in new and different ways. In a later passage, he also refers to the “vox mundi” as a “carrier or potentially enlightening alterity” (83). Voices, Pettman writes, “transgress the neat divisions we make between ‘us’ and ‘them’, at all scales and junctures” (6). Thus, Pettman’s suggestion is that “by listening to the ‘voices’ that lie dormant in the surrounding world […] we may in turn foster a more sustainable relationship with [the] local matrix of specific existences” (85), be they human or otherwise.This formulation of sonic intimacy provides a productive conceptual frame for thinking through Raaf’s and Lukatoyboy’s use of walkie-talkies. The contention in this article is that these two projects are striking for the way that they both use walkie-talkies to explore, simultaneously, this double articulation or dual orientation of sonic intimacy—a turning inwards to capture more private and personal experiences and conversations, and a turning outwards to capture the vox mundi. Employing Pettman’s notion of sonic intimacy as a conceptual frame, I trace below the different ways that these two projects incorporate walkie-talkies in order to develop mediated forms of wandering that seek to capture place-based sonic ambiances and sonic intimacies.Sabrina Raaf, Saturday (2002)US sound artist Sabrina Raaf’s Saturday (2002) is a sound-based art installation based on recordings of “stolen conversations” that Raaf gathered over many Saturdays in Humboldt Park, Chicago. Raaf’s work harks back to the early marketing of walkie-talkie toys as spyware. In Raaf’s hands, this device is used not for engaging in intimate one-to-one conversation, but for listening in on, and capturing, the intimate conversations of others. In other words, she uses this device, as the Nextel slogan goes, for “communication without permission to communicate” (“Nextel”). Raaf’s inspiration for the piece was twofold. First, she has noted that “with the overuse of radio frequency bands for wireless communications, there comes the increased occurrence of crossed lines where a private conversation becomes accidentally shared” (Raaf). Reminiscent of Francis Ford Coppola’s film The Conversation (1974), in which surveillance expert Harry Caul (Gene Hackman) records the conversation of a couple as they walk through crowded Union Square in San Francisco, Raaf used a combination of walkie-talkies, CB radios, and “various other forms of consumer spy […] technology in order to actively harvest such communication leaks” (Raaf). The second source of inspiration was noticing the “sheer quantity of non-phone, low tech, radio transmissions that were constantly being sent around [the] neighbourhood”, transmissions that were easily intercepted. These conversations were eclectic in composition and character:The transmissions included communications between gang members on street corners nearby and group conversations between friends talking about changes in the neighbourhood and their families. There were raw, intimate conversations and often even late night sex talk between potential lovers. (Raaf)What struck Raaf about these conversations, these transmissions, was that there was “a furtive quality” to most of them, and “a particular daringness to their tone”.During her Saturday wanderings, Raaf complemented her recordings of stolen snippets of conversation with recordings of the “voice” of the surrounding neighbourhood—“the women singing out their windows to their radios, the young men in their low rider cars circling the block, the children, the ice cream carts, etc. These are the sounds that are mixed into the piece” (Raaf).Audience engagement with Saturday involves a kind of austere intimacy of its own that seems befitting of a surveillance-inspired sonic portrait of urban and private life. The piece is accessed via an interactive glove. This glove is white in colour and about the size of a large gardening glove, with a Velcro strap that fastens across the hand, like a cycling glove. The glove, which only has coverings for thumb and first two fingers (it is missing the ring and little fingers) is wired into and rests on top of a roughly A4-sized white rectangular box. This box, which is mounted onto the wall of an all-white gallery space at the short end, serves as a small shelf. The displayed glove is illuminated by a discrete, bent-arm desk lamp, that protrudes from the shelf near the gallery wall. Above the shelf are a series of wall-mounted colour images that relate to the project. In order to hear the soundtrack of Saturday, gallery visitors approach the shelf, put on the glove, and “magically just press their fingertips to their forehead [to] hear the sound without the use of their ears” (Raaf). The glove, Raaf explains, “is outfitted with leading edge audio electronic devices called ‘bone transducers’ […]. These transducers transmit sound in a very unusual fashion. They translate sound into vibration patterns which resonate through bone” (Raaf).Employing this technique, Raaf explains, “permits a new way of listening”:The user places their fingers to their forehead—in a gesture akin to Rodin’s The Thinker or of a clairvoyant—in order to tap into the lives of strangers. Pressing different combinations of fingers to the temple yield plural viewpoints and group conversations. These sounds are literally mixed in the bones of the listener. (Raaf) The result is a (literally and figuratively) touching sonic portrait of Humboldt Park, its residents, and the “voice” of its surrounding neighbourhoods. Through the unique technosomatic (Richardson) apparatus—combinations of gestures that convey the soundscape directly through the bones and body—those engaging with Saturday get to hear voices in/of/around Humboldt Park. It is a portrait that combines sonic intimacy in the two forms described earlier in this article. In its inward-focused form, the gallery visitor-listener is positioned as a voyeur of sorts, listening into stolen snippets of private and personal relationships, experiences, and interactions. And, in its outward-focused form, the gallery visitor-listener encounters a soundscape in which an array of agents, entities, and objects are also given a voice. Additional work performed by this piece, it seems to me, is to be found in the intermingling of these two form of sonic intimacy—the personal and the environmental—and the way that they prompt reflection on mediation, place, urban life, others, and intimacy. That is to say that, beyond its particular sonic portrait of Humboldt Park, Saturday works in “clearing some conceptual space” in the mind of the departing gallery visitor such that they might “listen for, if not precisely to, the collective, polyphonic ‘voice of the world’” (Pettman 6) as they go about their day-to-day lives.Lukatoyboy, Walk That Sound (2014)The second project, Walk That Sound, by Serbian sound artist Lukatoyboy was completed for the 2014 CTM festival. CTM is an annual festival event that is staged in Berlin and dedicated to “adventurous music and art” (CTM Festival, “About”). A key project within the festival is CTM Radio Lab. The Lab supports works, commissioned by CTM Festival and Deutschlandradio Kultur – Hörspiel/Klangkunst (among other partnering organisations), that seek to pair and explore the “specific artistic possibilities of radio with the potentials of live performance or installation” (CTM Festival, “Projects”). Lukatoyboy’s Walk That Sound was one of two commissioned pieces for the 2014 CTM Radio Lab. The project used the “commonplace yet often forgotten walkie-talkie” (CTM Festival, “Projects”) to create a moving urban sound portrait in the area around the Kottbusser Tor U-Bahn station in Berlin-Kreuzberg. Walk That Sound recruited participants—“mobile scouts”—to rove around the Kottbusser Tor area (CTM Festival, “Projects”). Armed with walkie-talkies, and playing with “the array of available and free frequencies, and the almost unlimited amount of users that can interact over these different channels”, the project captured the dispatches via walkie-talkie of each participant (CTM Festival, “Projects”). The resultant recording of Walk That Sound—which was aired on Deutschlandradio (see Lukatoyboy), part of a long tradition of transmitting experimental music and sound art on German radio (Cory)—forms an eclectic soundscape.The work juxtaposes snippets of dialogue shared between the mobile scouts, overheard mobile phone conversations, and moments of relative quietude, where the subdued soundtrack is formed by the ambient sounds—the “voice”—of the Kottbusser Tor area. This voice includes distant traffic, the distinctive auditory ticking of pedestrian lights, and moments of tumult and agitation, such as the sounds of construction work, car horns, emergency services vehicle sirens, a bottle bouncing on the pavement, and various other repetitive yet difficult to identify industrial sounds. This voice trails off towards the end of the recording into extended walkie-talkie produced static or squelch. The topics covered within the “crackling dialogues” (CTM Festival, “Projects”) of the mobile scouts ranged widely. There were banal observations (“I just stepped on a used tissue”; “people are crossing the street”; “there are 150 trains”)—wonderings that bear strong similarities with French writer Georges Perec’s well-known experimental descriptions of everyday Parisian life in the 1970s (Perec “An Attempt”). There were also intimate, confiding, flirtatious remarks (“Do you want to come to Turkey with me?”), as well as a number of playfully paranoid observations and quips (“I like to lie”; “I can see you”; “do you feel like you are being recorded?”; “I’m being followed”) that seem to speak to the fraught history of Berlin in particular as well as the complicated character of urban life in general—as Pettman asks, “what does ‘together’ signify in a socioeconomic system so efficient in producing alienation and isolation?” (92).In sum, Walk That Sound is a strangely moving exploration of sonic intimacy, one that shifts between many different registers and points of focus—much like urban wandering itself. As a work, it is variously funny, smart, paranoid, intimate, expansive, difficult to decipher, and, at times, even difficult to listen to. Pettman argues that, “thanks in large part to the industrialization of the human ear […], we have lost the capacity to hear the vox mundi, which is […] the sum total of cacophonous, heterogeneous, incommensurate, and unsynthesizable sounds of the postnatural world” (8). Walk That Sound functions almost like a response to this dilemma. One comes away from listening to it with a heightened awareness of, appreciation for, and aural connection to the rich messiness of the polyphonic contemporary urban vox mundi. ConclusionThe argument of this article is that Sabrina Raaf’s Saturday and Lukatoyboy’s Walk That Sound are two projects that both incorporate walkie-talkies in order to develop mediated forms of wandering that seek to capture place-based sonic ambiances and sonic intimacies. Drawing on Pettman’s notion of “sonic intimacy”, examination of these projects has opened consideration around voice, analogue technology, and what Nick Couldry refers to as “an obligation to listen” (Couldry 580). In order to be heard, Pettman remarks, and “in order to be considered a voice at all”, and therefore as “something worth heeding”, the vox mundi “must arrive intimately, or else it is experienced as noise or static” (Pettman 83). In both the projects discussed here—Saturday and Walk That Sound—the walkie-talkie provides this means of “intimate arrival”. As half-duplex communication devices, walkie-talkies have always fulfilled a double function: communicating and listening. This dual functionality is exploited in new ways by Raaf and Lukatoyboy. In their projects, both artists turn the microphone outwards, such that the walkie-talkie becomes not just a device for communicating while in the field, but also—and more strikingly—it becomes a field recording device. The result of which is that this simple, “playful” communication device is utilised in these two projects in two ways: on the one hand, as a “carrier of potentially enlightening alterity” (Pettman 83), a means of encouraging “potential encounters” (89) with strangers who have been thrown together and who cross paths, and, on the other hand, as a means of fostering “an environmental awareness” (89) of the world around us. In developing these prompts, Raaf and Lukatoyboy build potential bridges between Pettman’s work on sonic intimacy, their own work, and the work of other experimental artists. For instance, in relation to potential encounters, there are clear points of connection with Blast Theory, a group who, as noted earlier, have utilised walkie-talkies and sound-based and other media technologies to explore issues around urban encounters with strangers that promote reflection on ideas and experiences of otherness and difference (see Wilken)—issues that are also implicit in the two works examined. In relation to environmental awareness, their work—as well as Pettman’s calls for greater sonic intimacy—brings renewed urgency to Georges Perec’s encouragement to “question the habitual” and to account for, and listen carefully to, “the common, the ordinary, the infraordinary, the background noise” (Perec “Approaches” 210).Walkie-talkies, for Raaf and Lukatoyboy, when reimagined as field recording devices as much as remote transmission technologies, thus “allow new forms of listening, which in turn afford new forms of being together” (Pettman 92), new forms of being in the world, and new forms of sonic intimacy. Both these artworks engage with, and explore, what’s at stake in a politics and ethics of listening. Pettman prompts us, as urban dweller-wanderers, to think about how we might “attend to the act of listening itself, rather than to a specific sound” (Pettman 1). His questioning, as this article has explored, is answered by the works from Raaf and Lukatoyboy in effective style and technique, setting up opportunities for aural attentiveness and experiential learning. However, it is up to us whether we are prepared to listen carefully and to open ourselves to such intimate sonic contact with others and with the environments in which we live.ReferencesAnon. “Die Welt als Labyrinth.” Internationale Situationiste 4 (Jan. 1960). International Situationist Online, 19 June 2019 <https://www.cddc.vt.edu/sionline/si/diewelt.html>Blast Theory. “Can You See Me Now?” Blast Theory, 19 June 2019 <https://www.blasttheory.co.uk/projects/can-you-see-me-now/>.———. “You Get Me.” Blast Theory, 19 June 2019 <https://wwww.blasttheory.co.uk/projects/you-get-me/>.Cory, Mark E. “Soundplay: The Polyphonous Tradition of German Radio Art.” Wireless Imagination: Sound, Radio, and the Avant-garde. Eds. Douglas Kahn and Gregory Whitehead. 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