Transmission Of Acoustic Signals Research Articles

Performance of a novel system for high-resolution tracking of marine fish societies

Recent advances in tracking systems have revolutionized our ability to study animal movement in the wild. In aquatic environments, high-resolution acoustic telemetry systems make it technically possible to simultaneously monitor large amounts of individuals at unprecedented spatial and temporal resolutions, providing a unique opportunity to study the behaviour and social interactions using a reality mining approach. Despite the potential, high-resolution telemetry systems have had very limited use in coastal marine areas due to the limitations that these environments pose to the transmission of acoustic signals. This study aims at designing and testing a high-resolution acoustic telemetry system to monitor, for the first time, a natural fish population in an open marine area. First, we conducted preliminary range tests and a computer simulation study to identify the optimal design of the telemetry system. Then, we performed a series of stationary and moving tests to characterize the performance of the system in terms of positioning efficiency and precision. Finally, we obtained a dataset corresponding to the movements of 170 concurrently tagged individuals to demonstrate the overall functioning of the system with a real study case of the behaviour of a small-bodied coastal species. Our results show that high-resolution acoustic telemetry systems efficiently generate positional data in marine systems, providing a precision of few meters, a temporal resolution of few seconds, and the possibility of tracking hundreds of individuals simultaneously. Data post-processing using a trajectory filter and movement models proved to be key to achieve a sub-meter positioning precision. The main limitation detected for our system was the restricted detection range, which was negatively affected by the stratification of the water column. Our work demonstrates that high-resolution acoustic telemetry systems are an effective method to monitor the movements of free-ranging individuals at the population level in coastal sites. By providing highly precise positioning estimates of large amounts of individuals, these systems represent a powerful tool to study key ecological processes regarding the social interactions of individuals, including social dynamics, collective movements, or responses to environmental perturbations, and to extend the studies to poorly studied small-sized species or life-stages.

Predicting the invasion of the acoustic niche: Potential distribution and call transmission efficiency of a newly introduced frog in Cuba

Leptodactylus fragilis is a recently introduced frog in Cuba, where it may impact local populations of amphibians in different ways. Here, we combined two methods to predict the invasion of the acoustic niche of Cuban amphibians by L. fragilis. We first use species distribution models to predict the spread and establishment of L. fragilis in Cuba. We then performed sound propagation experiments to evaluate the potential invasion of the acoustic niche in predicted suitable areas for the presence of L. fragilis. This species could have a successful establishment, spreading mainly in open areas, where its advertisement calls propagate efficiently, with low attenuation and discrete temporal-spectral degradation at short distances. The optimal transmission of acoustic signals in such areas might interfere with the acoustic communication of the endemic bufonid Peltophryne empusa, with potential negative effects on mate choice and breeding success. Predictions of habitat suitability, in combination with evidences of optimal transmission of advertisement calls of invasive amphibians, could be a valuable tool for rapid prediction of the potential impact of such species and the identification of prioritized areas to implement management strategies.

Male orientation on vocalization perches could optimize acoustic signal transmission in anurans

AbstractAcoustic signals are distorted by vegetation, wind currents, or other sounds when transmitted through the environment. Consequently, vocalizations with features that optimize sound transmission or behaviors that improve the efficacy of communication have evolved in many animal species. Among behavioral strategies, some species call from perches above the ground to increase the propagation distance of their acoustic signals. However, the orientation in the perch also influences the transmission of the vocalizations, so that frogs calling from different orientations (i.e., horizontal, upward, or downward) may affect differently the quality and efficacy of sound transmission. We implemented a sound transmission experiment to test for the effect of calling orientation (upward, downward, and horizontal) and distance on the attenuation and degradation of advertisement calls in the common dink frog Diasporus diastema. We broadcasted and re‐recorded advertisement calls at 2 m height, setting the speaker in three directions (upward, downward, and horizontal) to simulate different signaler orientations. We found that attenuation of the advertisement calls is significantly reduced when the speaker was directed either upward or downward, rather than horizontally. However, the degradation of call is lower when the speaker is direct horizontally. Since calls produced from either upward or downward orientations could travel farther, they could be used to signal male spatial location, while calls produced from a horizontal position could provide information on male quality at shorter distances at advanced phases of courtship.

Wireless information and power transfer for underwater acoustic time‐reversed NOMA

The acoustic signal transmission over the underwater channel has a limited sum rate and it consumes high power due to the properties of the underwater environment. This study attempts to use the non-orthogonal multiple access (NOMA) technologies for underwater communications. NOMA can be an attractive candidate for underwater communication due to its high spectral efficiency, resistance for carrier frequency offset, and efficient energy consumption. To cope with the hard-recharging capability of the underwater wireless sensor nodes caused by the ocean environment, this study proposes a novel transmission scheme called time-reversed NOMA (TR-NOMA) for underwater communication. In the proposed TR-NOMA, a single-input multiple-output NOMA scheme with a passive-time reversal technique is proposed to reduce the time–frequency dispersion of the underwater acoustic channels. Consequently, simultaneous wireless information and power transfer (SWIPT) can be applied for underwater TR-NOMA. In this study, a SWIPT-NOMA is postposed to harvest energy in downlink transmission from the transmitted signal. The bit error rate (BER) and the outage probability are used to characterise the performance of the proposed TR-NOMA scheme and simulation results show how the proposed TR-NOMA significantly outperforms the conventional NOMA schemes. Additionally, a mathematical framework for the average BER of TR-NOMA is delineated.

Acoustic signal analysis of instrument\u2013tissue interaction for minimally invasive interventions

PurposeMinimally invasive surgery (MIS) has become the standard for many surgical procedures as it minimizes trauma, reduces infection rates and shortens hospitalization. However, the manipulation of objects in the surgical workspace can be difficult due to the unintuitive handling of instruments and limited range of motion. Apart from the advantages of robot-assisted systems such as augmented view or improved dexterity, both robotic and MIS techniques introduce drawbacks such as limited haptic perception and their major reliance on visual perception.MethodsIn order to address the above-mentioned limitations, a perception study was conducted to investigate whether the transmission of intra-abdominal acoustic signals can potentially improve the perception during MIS. To investigate whether these acoustic signals can be used as a basis for further automated analysis, a large audio data set capturing the application of electrosurgery on different types of porcine tissue was acquired. A sliding window technique was applied to compute log-mel-spectrograms, which were fed to a pre-trained convolutional neural network for feature extraction. A fully connected layer was trained on the intermediate feature representation to classify instrument–tissue interaction.ResultsThe perception study revealed that acoustic feedback has potential to improve the perception during MIS and to serve as a basis for further automated analysis. The proposed classification pipeline yielded excellent performance for four types of instrument–tissue interaction (muscle, fascia, liver and fatty tissue) and achieved top-1 accuracies of up to 89.9%. Moreover, our model is able to distinguish electrosurgical operation modes with an overall classification accuracy of 86.40%.ConclusionOur proof-of-principle indicates great application potential for guidance systems in MIS, such as controlled tissue resection. Supported by a pilot perception study with surgeons, we believe that utilizing audio signals as an additional information channel has great potential to improve the surgical performance and to partly compensate the loss of haptic feedback.

FGF22 promotes generation of ribbon synapses through downregulating MEF2D.

Cochlear ribbon synapses play a pivotal role in the prompt and precise acoustic signal transmission from inner hair cells (IHCs) to the spiral ganglion neurons, while noise and aging can damage ribbon synapses, resulting in sensorineural hearing loss. Recently, we described reduced fibroblast growth factor 22 (FGF22) and augmented myocyte enhancer factor 2D (MEF2D) in an ototoxicity mouse model with impaired ribbon synapses. Here, we investigated the mechanisms that underlie the FGF22/MEF2D- regulated impairment of ribbon synapses. We generated adeno-associated virus (AAV) carrying FGF22, shFGF22, MEF2D, shMEF2D, calcineurin (CalN), shCalN or corresponding scramble controls for transduction of cultured mouse hair cells. We found that FGF22 was a suppressor for MEF2D, but not vice versa. Moreover, FGF22 likely induced increases in the calcium influx into IHCs to activate CalN, which subsequently inhibited MEF2D. Cochlear infusion of AAV-shFGF22 activated MEF2D, reduced ribbon synapse number and impaired hearing function, which were all abolished by co-infusion of AAV-shMEF2D. Hence, our data suggest that the ribbon synapses may be regulated by FGF22/calcium/CalN/MEF2D signaling, which implied novel therapeutic targets for hearing loss.

Development of Underwater Acoustic Channel Model for Wireless Sensor Network in Tank

The physical quantity of interest can be detected using wireless sensor network. The concept of wireless sensor network used to explore difficult areas to access is extended to underwater applications. Efforts are made to focus on design and development of reliable, feasible and robust system for communication in underwater environment. The scenario of communication is completely different for terrestrial and underwater environment. Underwater wireless communication is accomplished by transmission of acoustic signal. Requirement exists to develop a model governing basic equations for acoustic frequency range for underwater acoustic communication. With excess quantity of sodium chloride in a underwater tank, the physical properties of the channel changes which alternately effects the communication. Using soft computing technique, the attenuation model is simulated which is a basic physical property taking change during underwater acoustic communication. The topology of sensor network in water is another challenging task because behaviors of acoustic sensor in underwater are completely different than terrestrial sensors. Thus the efforts are made to devise a model of acoustic frequency environment in water using basic relationships of various physical phenomena. The Channel propagation model is devised that helps to understand percentage area coverage for the received signal strength of the transmitted acoustic signal. Thus the underwater acoustic signal channel propagation model is presented which helps to focus on communication scenario in water and proceed for application.

Directional transmission of ultra-high frequency acoustic signals based on metamaterial structure

Cell photoacoustic detection of acoustic signals has serious problems of transmission loss and difficulty in acquisition. Based on the acoustic transmission characteristics of acoustic supermaterials, the acoustic wave directional transmission model is designed using COMSOL software, and a finite element simulation experiment was carried out. Experiments show that the model designed in this paper has good sound wave focusing and acoustic wave directional transmission effects. According to the specific application in different environments, this paper designs a variety of transmission models with different structures and carries out comparative experiments to verify the influence of complex model structures on the directional transmission of sound waves. At the same time, the experimental analysis of the acoustic wave directional transmission effect of the model under different frequency segments is carried out, and the possibility of acoustic wave logic operation is verified. Models can be applied to high frequency acoustic signal acquisition and sound wave transmission in complex environments. These studies have important significance for the development of cell photoacoustic detection technology and the application of metamaterial structures and have good practical merit.

Hydroacoustic stand for evaluating underwater sound systems in a measurement pool

Measurement of sonar parameters in laboratory conditions is a powerful tool for development, control and diagnostics. The realization of such a tool requires the construction of a measuring pool and its equipment with digital channels for receiving and generating sonar signals. An essential requirement for the measuring equipment is to quantify time and amplitude signals with the necessary accuracy and speed. The paper presents a new stand for evaluating the parameters of active and passive sonar systems. The stand is based on the PXI console of National Instruments and the underwater receiving channel of Bruel & Kjaer. Software solutions for the synthesis, transmission, reception and analysis of acoustic signals with different pulse lengths and intrapulse modulations have been developed through the LabVIEW software platform. VI instruments were developed for digital processing, and visualization of signals, and the ability to measure Sonar Transducer parameters in a test tank.

Effects of Various Antifouling Coatings and Fouling on Marine Sonar Performance.

There is a rising imperative to increase the operational availability of maritime vessels by extending the time between full docking cycles. To achieve operational efficacy, maritime vessels must remain clear of biological growth. Such growth can cause significant increases in frictional drag, thereby reducing speed, range and fuel efficiency and decreasing the sensitivity of acoustic sensors. The impact that various stages of fouling have on acoustic equipment is unclear. It is also unclear to what extent antifouling techniques interfere with the transmission of acoustic signals. In this study, to examine this effect, neoprene samples were coated with three antifouling coatings, namely, Intersmooth 7460HS, HempaGuard X7 and Hempasil X3. Other neoprene samples were left uncoated but were imbedded with the biocide, 4,5-dichloro-2-octyl-4-isothiazolin-3-one (DCOIT) during the mixing and curing process. Uncoated nitrile samples that had varying levels of fouling from immersion in Port Phillip Bay, Australia, for 92, 156 and 239 days were also extracted. The acoustic properties of these samples were measured using an acoustic insertion loss test and compared to uncoated neoprene or nitrile to ascertain the acoustic effects of the applications of antifouling coatings as well as the fouling growth itself. A T-peel test was performed on all coated samples in an attempt to understand the adhesive properties of the coatings when applied to neoprene. It was found that the application of antifouling coatings had little effect on the transmission characteristics of the neoprene with approximately 1 dB loss. The embedment of DCOIT, however, has a chance of causing aeration in the neoprene, which can heavily hamper transmission. An assessment of the effect of the fouling growth found that light and medium fouling levels produced little transmission loss, whereas more extreme fouling lead to a 9 dB transmission loss. The adhesion properties of the coatings were investigated but not fully ascertained as tensile yielding occurred before peeling. However, various failure modes are presented and discussed in this study.

Realization of complex curved waveguide based on local resonant 3D metamaterial

To overcome the negative impact of diffraction effect on the transmission wave front at the bend and to improve the transmission efficiency of acoustic wave in the bend waveguide, the finite element method by COMSOL was used to simulate the propagation characteristics of acoustic wave in the structure of bending acoustic waveguide, based on local resonance acoustic metamaterials. Specifically, the vibration mechanism of three-dimensional (3D) component locally resonant phononic crystals was presented, and the acoustic metamaterial models of M-shaped, L-shaped and S-shaped bent waveguides were constructed on the basis of the protocells. The local resonance between the acoustic wave and the protocells in the waveguide model was investigated, in order to produce the nondestructive bending propagation effect of the acoustic wave. The results of finite element analysis show that the plane acoustic waves incident from the M-shaped, L-shaped and S-shaped bending waveguide model will propagate directionally along the model structure after being controlled at the resonance frequency. These results confirm the flexibility and feasibility of the bending acoustic waveguide model designed by the local resonance acoustic metamaterials. In addition, the acoustic waveguide model in long-distance special environment was designed and the low loss transmission of acoustic signal was implemented. This study provides a new solution for engineering applications, such as ultrasonic signal detection and underwater acoustic communication transmission.

Pulse system for evaluation of parameters of electro-acoustic transducers in a hydroacoustic tank

In the report an applicationof the pulse method is presented for hydroacoustic test tank measurements. The basic test tank hydroacoustic equipment is from Bruel&Kjaer with National Instruments based control and measurement hardware and software platform. A LabVIEW software is used for synthesis, transmission and measurement of acoustic signals with different pulse lengths and intra-pulse modulations. A number of VI’s are designed for digital signal processing and visualization of the signals and results. Capabilities are shown for test tank measurements of sonar transducers pattern and quality factor.

Speaker responses to indirect evidence of acoustic signal transmission conditions.

Evidence has been accumulating that speakers adjust their speech production to account for conditions of signal transmission to an interlocutor, in addition to speaker- and listener-related influences. This study manipulated acoustic transmission conditions between speakers and a researcher while they completed dyadic cooperative puzzle tasks. Speakers heard evidence of four transmission perturbations (intensity increase/decrease, pitch increase/decrease) only indirectly, i.e., via changes in the researcher's voice. Analysis of speakers' conversational turns across conditions (baseline + four partner-voice manipulations) showed significant group-level imitation of transmission manipulations of partner voice intensity, with no general response to shifts in partner voice pitch. Significant voice alterations were also observed for individual speakers in intensity, with substantial inter-talker variability in responses. Thirteen of 29 speakers exclusively imitated the manipulation of partner intensity, 4/29 speakers exclusively opposed the transmission manipulation, and 4/29 speakers showed both response types. The presence of opposition responses coupled with a relatively low-magnitude group-level convergence suggests the possibility of a compensatory force at work in at least some speakers, adjusting for changes made during signal transmission despite their lack of direct experience with the transmission manipulation effects.

Optical reflection and waveguiding of sound by photo-thermally induced barriers.

Control and manipulation of sound is of critical importance to many different scientific and engineering fields, requiring the design of rigid physical structures with precise geometries and material properties for the desired acoustics. In this work, we demonstrate the ability to manipulate the direction and magnitude of sound waves traveling in air using laser light, without the need for physical interfaces associated with different materials. Efficient reflection of sound waves off of transient, optically generated, abrupt air density barriers is demonstrated, with acoustic reflections greater than 25% of the incident acoustic wave amplitude. Implementation of multiple barriers, can result in complete suppress the transmission of incident acoustic signals as great as 70 dB. Additionally, shaping the laser beam acoustic waveguides can be generated with dramatically reduced transmission losses.

Adaptación acústica del canto de Turdus leucomelas (Passeriformes: Turdidae) a diferentes niveles de ruido antrópico, en el área metropolitana de Belém de Pará, Brasil

Anthropogenic noise in urban environments is a major challenge for those species that depend on the transmission of acoustic signals to communicate. To avoid being masked by background noise, some bird species are able to make adjustments in their songs. Studies on vocal adjustment for tropical birds are still scarce and are of interest since both the urban structure and the vegetation associated with urban habitats differ significantly with respect to the cities of temperate climates. In this research we studied the changes in the song parameters of the pale-breasted thrush (Turdus leucomelas) in an urban environment of the metropolitan area of Belém (Brazil). To this end, bird songs were recorded and ambient noise was measured between September and November 2008, in three different acoustic environments (urban, suburban and rural) along an urban gradient. The songs of 12 individuals per area were selected (a total of 36). Possible differences between song parameters were analyzed by ANOVAs. To assess the noise impact on bird song, we only considered the spectrum of environmental noise within the range of vocalizations of the species. In general, birds of urban habitats presented songs with higher maximum frequencies and with a wider range of notes, than their counterparts in suburban and rural areas. The differences were more pronounced in relation to rural areas. No differences in the minimum frequencies, the concentration of energy, or the average duration of the notes were found. These results differ from other studies and could possibly indicate variations in the way birds try to succeed in habitats with high ambient noise. It is necessary further exploration on the role of these changes in the effective improvement of intra-specific communication for the species in such environments.

液体中激光声传输特性

In order to understand the transmission properties of laser-induced acoustic in liquid, the transmission properties of laser-induced acoustic were analyzed theoretically, and the experimental research on the laser-induced acoustic was carried out by using high speed camera and fiber MEMS hydrophone. Wavelet transform was used to analyze the spectrum characteristics of the laser-induced acoustic signals at different locations. The results show that the laser-induced acoustic is a pulsating source, amplitude and distance are inversely proportional in the process of laser acoustic signal transmission; laser acoustic analysis of band memory has obvious dominant frequency, with peak frequency stability of 3.1 kHz and bandwidth stability of 3 kHz; low frequency signal energy accounted for more than 70% of the total energy, high frequency part is mainly noise; from the power spectrum waveform analysis, low frequency signal amplitude with time and distance attenuation is slower, and high frequency noise with time and distance transform decays faster.

Source level and calling depth distributions of migrating bowhead whale calls in the shallow Beaufort Sea.

Automated and manual acoustic localizations of migrating bowhead whales were used to estimate source level and calling depth distributions of their frequency-modulated-modulated calls over seven years between 2008 and 2014. Whale positions were initially triangulated using directional autonomous seafloor acoustic recorders, deployed between 25 and 55 m water depth near Kaktovik, Alaska, during the fall westward migration. Calling depths were estimated by minimizing the "discrepancy" between source level estimates from at least three recorders detecting the same call. Applying a detailed waveguide propagation model to the data yielded broadband source levels of 161 ± 9 dB re 1 μPa2 s at 1 m (SEL) for calls received between 20 and 170 Hz. Applying a simpler 15 log10(R) power-law propagation model yielded SEL source levels of 158 ± 10 dB. The most probable calling depths lay between 22 and 30 m: optimal depths for long-range acoustic signal transmission in this particular environment.

The dynamic excitation of a granular chain for biomedical ultrasound applications: contact mechanics finite element analysis and validation

There has been recent interest in the transmission of acoustic signals along granular chains of spherical beads to produce waveforms of relevance to biomedical ultrasound applications. Hertzian contact between adjacent beads can introduce different harmonic content into the signal as it propagates. This transduction mechanism has the potential to be of use in both diagnostic and therapeutic ultrasound applications, and is the object of the study presented here. Although discrete dynamics models of this behaviour exist, a more comprehensive solution must be sought if changes in shape and deformation of individual beads are to be considered. Thus, the finite element method was used to investigate the dynamics of a granular chain of six, 1 mm diameter chrome steel spherical beads excited at one end using a sinusoidal displacement signal at 73 kHz. Output from this model was compared with the solution provided by the discrete dynamics model, and good overall agreement obtained. In addition, it was able to resolve the complex dynamics of the granular chain, including the multiple collisions which occur. It was demonstrated that under dynamic excitation conditions, the inability of discrete mechanics models to account for elastic deformation of the beads when these lose contact, could lead to discrepancies with experimental observations.

Large hoisting machinery local damage acoustic emission monitoring of optical information acquisition research

AE technology, an advanced fault diagnosis technique,is impacted by environmental noise during monitoring equipment. The occurrence of interfere noise,the fashion of interfere and the effect to the system in the AE automatic online monitoring system is analyzed. At present, most of the acoustic emission signal transmission by cable, this way of transmission has a limited transmission distance, shortcomings and so on signal easily disturbed. Is proposed in this paper based on the optical fiber transmission technology, designed and developed a information collection system based on optical fiber acoustic emission monitoring.This way has the advantages of long distance transmission, strong anti-jamming capability.

AUV Underwater Positioning Algorithm Based on Interactive Assistance of SINS and LBL.

This paper studies an underwater positioning algorithm based on the interactive assistance of a strapdown inertial navigation system (SINS) and LBL, and this algorithm mainly includes an optimal correlation algorithm with aided tracking of an SINS/Doppler velocity log (DVL)/magnetic compass pilot (MCP), a three-dimensional TDOA positioning algorithm of Taylor series expansion and a multi-sensor information fusion algorithm. The final simulation results show that compared to traditional underwater positioning algorithms, this scheme can not only directly correct accumulative errors caused by a dead reckoning algorithm, but also solves the problem of ambiguous correlation peaks caused by multipath transmission of underwater acoustic signals. The proposed method can calibrate the accumulative error of the AUV position more directly and effectively, which prolongs the underwater operating duration of the AUV.