Search Results (156)

This paper presents a miniaturized and highly accurate saltwater concentration monitoring system based on Capacitive Micromachined Ultrasonic Transducer (CMUT) array technology. The system incorporates a highly integrated CMUT array with a compact footprint of 5 mm × 5 mm, capable of both transmitting and receiving ultrasonic signals, which significantly contributes to the system’s miniaturization and portability. To ensure accurate compensation for temperature-dependent variations in sound velocity, a TA610A temperature sensor is integrated for continuous real-time monitoring of the salt solution temperature. By acquiring ultrasonic echo signals, the system calculates the time-of-flight (TOF) of the acoustic waves. Based on the TOF and real-time temperature data, the sound velocity is determined, and the salt concentration is subsequently derived with temperature compensation applied to enhance measurement accuracy. Experimental results show a measurement precision of 0.1% and a maximum absolute error of 0.02%, confirming the system’s high accuracy and robustness. Combining stability, reliability, and a compact real-time sensing design, the proposed CMUT-based system holds significant promise for practical deployment in various industrial and environmental monitoring scenarios. Full article

Acoustic material classification under non-line-of-sight (NLOS) conditions—where direct sound paths are obstructed—is a challenging task due to echo attenuation, complex reflections, and noise effects. This study aims to improve NLOS material recognition by introducing a novel wavelet–acoustic hybrid feature fusion method integrated with deep recurrent neural network architectures. Echo signals from nine different materials were collected using the newly developed ANLOS-R (Acoustic Non-Line-of-Sight Recognition) dataset, which was specifically designed to simulate realistic NLOS propagation environments. From these recordings, time-domain acoustic features and multi-scale wavelet-based energy and entropy statistics were extracted using ten wavelet families. The resulting 70-dimensional hybrid feature set was used to train several deep learning architectures, including Long Short-Term Memory (LSTM), Bidirectional LSTM (BiLSTM), Gated Recurrent Unit (GRU), and Convolutional Neural Network–LSTM (CNN–LSTM). Among these, the CNN–LSTM achieved the highest balanced accuracy and macro-F1 score of 0.99, showing strong generalization and convergence performance. SHapley Additive exPlanations (SHAP) analysis indicated that Mel-Frequency Cepstral Coefficients (MFCCs) and wavelet entropy–energy features play complementary roles in material discrimination. The proposed approach provides a robust and interpretable framework for real-time NLOS acoustic sensing, bridging data-driven deep learning with the physical understanding of acoustic material behavior. Full article

This paper focuses on examining the impact of introducing sound scattering in room acoustic modelling, using a ray tracing approach. A parametric study is conducted on a simplified shoebox auditorium, isolating distinct factors, such as the average absorption of the room, room geometry, volume of the space or the introduction of prismatic-shape diffusers. Diffusion is considered by assigning a scattering coefficient (s) to the surfaces, except in the analysis of a prismatic diffuser, which is modelled using a geometric approach. Changes in the reverberation time are analyzed alongside their corresponding just noticeable differences (JNDs). It was found that sound scattering can reduce reverberation time, especially in rooms with parallel walls, but only when sufficient and well-distributed sound absorption is present. Geometric modifications that remove parallelism reduce flutter echoes and can decrease reliance on scattering. Volume scaling of a room has negligible perceptual influence on sound scattering, whereas modifying room proportions offers a stronger influence on reverberation perception. Prismatic diffusers provide efficient geometric diffusion, achieving outcomes comparable to flat surfaces assigned with medium sound scattering coefficients. Full article

This essay contends that Jean-Luc Godard’s late digital cinema elaborates a geopolitical aesthetics in which Europe confronts the return of its repressed histories through the very instability of the digital image. While Europe has long functioned in Godard’s work as both theme and epistemic horizon—echoing the Hegelian cartographies—Film Socialisme (2010) and The Image Book (2018) transform this Eurocentrism into a site of crisis. In these films, what Fredric Jameson terms the “political unconscious” (1981) emerges through the spectral return of Palestine and the Arab world, compelling a reckoning with colonial legacies and the limits of representation. The digital turn proves decisive. Godard mobilizes pixelation, saturation, glitch, and decomposed sound to reveal what might be called the technological unconscious of the medium. I develop the concept of “Digital Orientalism” to designate how Orientalist chronotopes persist in the digital age yet are unsettled by Godard’s experimental manipulation of audiovisual fragments. Through close readings of Film Socialisme and The Image Book, which incorporates works by Arab filmmakers including Youssef Chahine, Nacer Khemir, Ossama Mohammed, and Wiam Simav Bedirxan, I show how Godard’s fractured montages produce symptomatic cartographies of the world-system where repression, memory, and accident collide. Full article

With the rapid development and widespread application of multibeam echo-sounding systems, large-scale and high-resolution seafloor topography can be efficiently acquired, enabling precise mapping of seabed terrain. However, due to complex oceanographic conditions, instrumental noise, and acoustic interferences, the acquired multibeam data often contain outliers that deviate from the true seafloor surface. These outliers can distort the representation of seafloor topography, adversely affecting subsequent geological analysis and engineering applications. To address this issue, a hybrid outlier detection method combining CUBE filtering with the Isolation Forest (IForest) algorithm, termed CUBE-IForest, is proposed. The method first employs CUBE filtering to remove gross outliers based on local uncertainty estimation, followed by the application of IForest to identify subtle anomalies in the refined data, achieving hierarchical detection of outliers. Experimental results based on in situ multibeam bathymetric data from the northeastern Pacific demonstrate that compared with traditional filtering methods the CUBE-IForest approach significantly improves detection accuracy and reduces both false positive and false negative rates by approximately 30%, confirming its efficiency and reliability in seafloor mapping and analysis. Full article

Subglacial topography is a critical boundary condition for ice sheet models projecting past and future ice sheet–climate interactions. Contemporary ice-sheet-wide bed topography datasets are partially derived using mass conservation, but approximately 75% of the most widely used Greenland Ice Sheet (GrIS) dataset is based on simple interpolation of airborne radio-echo sounding (RES) measurements, such as kriging or streamline diffusion. Due to limited independent validation data, the errors and biases in this approach are poorly understood, creating largely unknown uncertainties in subglacial topography. Here, we interpolated synthetic RES observations of bed topography over ice-free areas with a known topography at a 5 m spatial resolution and quantify discrepancies. We found that the absolute error in kriged bed topography increases with distance from the input data, though at a reduced rate than previously estimated. The difference between an interpolated elevation estimate and the local mean elevation is a strong predictor of real bed errors (R² = 0.72), with further improvement as input observation sparsity increases (R² > 0.82). We propose a method to quantify and reduce uncertainty in kriged bed topography in sparsely surveyed regions, reducing uncertainty for at least 56% of the kriged interior at a 99% confidence interval. Our results suggest that subglacial depth is on average 5 m deeper than previous estimates, though individual areas may be shallower or deeper (σ = 41 m). Consequently, the area grounded below sea level is likely underestimated by 2%, increasing to 29% for regions deeper than 200 m. These findings have potential implications for the future stability of the GrIS under climate change. Full article

The unique features of annular phased array transducers, such as ring-shaped elements and the concentric configuration, cause them to behave differently from commonly used linear array transducers, in terms of sound field distribution and pulse–echo response. Consequently, standard techniques for assessing linear array transducers can introduce significant errors when applied to annular array transducers, especially concerning element-to-element sensitivity variance. This study investigates the consistency of element sensitivity in annular phased array transducers. Through theoretical analysis, a Long-Belt source assumption model was developed based on the Rayleigh integral to characterize the responses of ring-shaped elements in an analytical and explicit form. The model suggests that the response amplitude is linearly correlated with the radial width of the element, which was validated by subsequent numerical simulations. Based on these findings, a modified sensitivity evaluation algorithm for annular array transducers is presented. The response voltage per unit width, rather than the total response voltage, is used to eliminate the influence of varying geometries and sizes across elements. The sensitivity variation of a 32-element annular array transducer was evaluated using the new algorithm. Compared to the uncorrected measurement, the maximum sensitivity variation was reduced significantly from 25 dB to 6 dB, revealing the transducer’s intrinsic consistency despite the different geometric features of each element. Due to its distinct geometry compared to the ring-shaped elements, the central element cannot be corrected or evaluated using this method. These results suggest that the proposed algorithm enables the more accurate evaluation of sensitivity consistency for annular phased array transducers, thereby improving measurement reliability in practical applications. Full article

Tidal flats play a vital role in coastal ecosystems by supporting biodiversity, mitigating natural hazards, and functioning as blue carbon reservoirs. However, monitoring their geomorphological changes remains challenging due to high turbidity, shallow depths, and tidal variability. Conventional approaches—such as satellite remote sensing, acoustic sounding, and topographic LiDAR—face limitations in resolution, accessibility, or coverage of submerged areas. Airborne bathymetric LiDAR (ABL), which uses green laser pulses to detect reflections from both the water surface and seabed, has emerged as a promising alternative. Unlike traditional discrete-return data, full waveform analysis offers greater accuracy, resolution, and reliability, enabling more flexible point cloud generation and extraction of additional signal parameters. A critical step in ABL processing is waveform decomposition, which separates complex returns into individual components. Conventional methods typically assume fixed models with three returns (water surface, water column, bottom), which perform adequately in clear waters but deteriorate under shallow and turbid conditions. To address these limitations, we propose an adaptive progressive Gaussian decomposition (APGD) tailored to tidal flat environments. APGD introduces adaptive signal range selection and termination criteria to suppress noise, better accommodate asymmetric echoes, and incorporates a water-layer classification module. Validation with datasets from Korea’s west coast tidal flats acquired by the Seahawk ABL system demonstrates that APGD outperforms both the vendor software and the conventional PGD, yielding higher reliability in bottom detection and improved bathymetric completeness. At the two test sites with different turbidity conditions, APGD achieved seabed coverage ratios of 66.7–70.4% and bottom-classification accuracies of 97.3% and 96.7%. Depth accuracy assessments further confirmed that APGD reduced mean depth errors compared with PGD, effectively minimizing systematic bias in bathymetric estimation. These results demonstrate APGD as a practical and effective tool for enhancing tidal flat monitoring and management. Full article

We present experimental results related to the features and geophysical conditions for the occurrence of the long-delay echo (LDE) signals in the medium-wave (MW) frequency range observed on 20 January 2025, at the Gor’kovskaya observatory near St. Petersburg (60.27° N, 29.38° E). A total of 19 series of experiments on guiding MF in the magnetosphere were carried out, while LDE signals were only registered on January 20, 2025, in evening hours, when the most disturbed conditions were observed (Kp = 4+, ΣKp = 27−). It was found that the LDE signals, with delay times of 310–322 ms, were observed in the evening hours under disturbed magnetic conditions. In such a case, the MW propagates into the magnetosphere to the magnetically conjugate point, is reflected from the topside ionosphere, and returns. The frequency of sounding signal f_SS exceeded the critical frequency of the F2 layer at Gor’kovskaya observatory foF2_GRK but was less than the critical frequency at the magnetic conjugated point foF2_MCP, foF2_GRK < f_SS < foF2_MCP. The LDE signals were observed in the narrow frequency range from 2100 to 2400 kHz. The background geophysical conditions during the occurrence of LDE signals were analyzed using the CADI ionosonde data and Swarm satellite observations. The plausible generation mechanisms for MW guiding in the magnetosphere are discussed. Full article

Multi-purpose gymnasiums are typically designed for sport events and large-scale gatherings. However, the gymnasium investigated in this study lacked sufficient consideration of acoustic performance during its design phase, resulting in severe echo problems, long reverberation time and poor speech intelligibility. These acoustic deficiencies limit its ability to host major events, reduce utilization efficiency and cannot be resolved by simply adjusting the sound reinforcement system. Conventional renovation strategies usually involve sound-absorbing materials on walls or ceilings, which are costly, labor-intensive and time-consuming. The case gymnasium discussed in this study has the particular advantage that its ceiling structure already provides partial sound absorption. To lower renovation costs and minimize construction workload, this research builds upon the existing ceiling structure and evaluates five renovation schemes through comparative analysis, proposing a renovation approach that remains economical while providing substantial performance benefits. The study calibrates the acoustic model through comparison between measurement and simulation in ODEON V16.0 software, and the validated model was further used to predict acoustic parameters under full occupancy across different schemes. Post-renovation field measurements confirm the reliability and accuracy of the proposed approach, offering a valuable reference for similar gymnasium acoustic retrofitting projects. Full article

In extremely harsh high-temperature environments in aerospace, industrial manufacturing and other fields, traditional ultrasonic temperature measurement technology has certain limitations. This paper proposes a differential single crystal sapphire ultrasonic temperature measurement method based on the magnetostrictive effect. This method abandons the traditional sensitive flexural structure and uses two single-crystal sapphire waveguides of the same material, same diameter, and slightly different lengths as sensing elements. By measuring the time delay difference between their end-face echoes, the sound velocity is inverted and the temperature is measured. COMSOL multi-physics v6.1 simulation was used to optimize the bias magnetic field design of the magnetostrictive transducer, which improved the system’s energy conversion efficiency and high-temperature stability. Experimental results show that in the range of 300–1200 °C, the sensor delay increases monotonically with increasing temperature, the sound speed shows a downward trend, and the repeatability error is less than 5%; the differential processing method effectively suppresses common mode noise in the range of 300–700 °C, and still shows high sensitivity above 800 °C. This research offers a technical solution with high reliability and accuracy for temperature monitoring in extreme environments such as those characterized by high temperatures and high pressures. Full article

Misconceptions about sound are common among primary-school pupils, but research on voice-interactive game-based learning remains limited, especially regarding the role of scaffolding. We investigated whether a voice-interactive 2D platformer with a three-tier scaffolding model improves learning about loudness, pitch, and echo. In a classroom-feasible randomized comparison, 45 third-graders were assigned to a scaffolded serious game (SSG), a non-scaffolded serious game (NSG), or traditional hands-on materials instruction (TRAD) on matched sound content. Outcomes were an immediate eight-item knowledge test and learner-centered ratings of perceived learning, flow, intrinsic motivation, and extraneous cognitive load (ECL). The knowledge test showed low internal consistency, so results involving this measure should be interpreted with caution. SSG yielded higher immediate learning than NSG and matched traditional instruction. Across experience measures, only intrinsic motivation differed, favoring NSG. Hierarchical regression revealed a motivation-by-structure effect: scaffolding strengthened the positive association between intrinsic motivation and test scores, whereas ECL was not predictive. Findings indicate that voice-interactive serious games can match near-term learning achieved with physical materials, and well-calibrated scaffolds help convert motivation into accurate encoding. We also map sound constructs to gameplay mechanics and provide a compact, classroom-feasible, replicable evaluation design for primary classrooms. Full article

Systemic sclerosis-associated pulmonary arterial hypertension (SSc-PAH) is a life-threatening vascular complication of SSc, marked by high morbidity and mortality. Early diagnosis remains a major challenge due to nonspecific symptoms and the limitations of conventional tools such as echocardiography (ECHO), pulmonary function tests (PFTs), and serum biomarkers. This review evaluates the emerging role of artificial intelligence (AI), particularly machine learning (ML) and deep learning (DL), in improving the diagnostic landscape of SSc-PAH. A comprehensive literature search was conducted across PubMed, Scopus, IEEE Xplore, Embase and Google Scholar to identify studies involving AI applications in SSc, pulmonary arterial hypertension (PAH), and their intersection. Evidence indicates that AI models can assist interpretation across modalities, including heart sounds, ECGs, chest X-rays (CXRs), ECHOs, CT pulmonary angiography (CTPA), and omics-based biomarkers. While several models show encouraging diagnostic performance, their accuracy varies by dataset and modality, and most require external validation against right heart catheterization (RHC)-confirmed cohorts. Integrating multimodal data through AI frameworks may enhance early recognition and individualized risk stratification; however, these tools remain exploratory. Future work should emphasize harmonized hemodynamic definitions, transparent validation protocols, and SSc-specific datasets to ensure clinical applicability and reproducibility. Full article

In extra-large spaces, the varying distances between distributed loudspeakers and listeners lead to sound delays in the loudspeakers’ concentrated projection areas. When combined with the inherent long-delay reflected sounds in those spaces, this dual effect exacerbates the echo problems and poses challenges to maintaining speech intelligibility. To explore the influence mechanism of echo interference on speech intelligibility in extra-large spaces, a questionnaire survey was carried out in two representative extra-large buildings, and then listening experiments were conducted in the laboratory under different echo conditions and impulse characteristics. The results highlighted that (1) apparent echo problems existed in extra-large spaces and severely affected speech intelligibility; (2) the echo phenomenon can be classified into three groups—no echo (0 ms), short delay (100 or 200 ms), and long delay (≥300 ms)—with the detrimental effect on intelligibility increasing across the groups; and (3) a curve was established to describe the relationship between speech intelligibility and STI in extra-large spaces, and compared with the standard curve, the STI thresholds require further adjustment. These findings indicate that echoes in extra-large spaces significantly impair speech intelligibility and reduce the accuracy of its prediction, and therefore should not be neglected. Full article

The deployment of traditional ground-penetrating radar (GPR) systems for ice detection on steep terrain presents substantial safety challenges for ground crews due to inaccessibility and hazardous working conditions. However, airborne GPR (AGPR) and radio echo sounding (RES) provide solutions to these difficulties. Assuming that ice is homogeneous, we introduce a perspective back-projection algorithm designed to process AGPR or RES data that directly searches for unobstructed refracted electromagnetic (EM) wave paths and focuses EM energy below the surface by computing path-specific travel times. The results from the 2D and 3D imaging tests indicate that the perspective back-projection algorithm can accurately image the ice–rock interface. However, Snell’s Law suggests that part of the energy may fail to propagate through the air–ice interface and reach either the ice–rock interface or the receivers in scenarios where the incident angle of an EM wave exceeds a certain threshold. This energy deficit can hinder the perspective back-projection algorithm from accurately imaging such ice–rock interfaces. Despite these limitations, the perspective back-projection algorithm remains a promising tool for imaging sub-ice interfaces in AGPR and RES ice detection. Full article