An ultra-enhanced near-infrared (NIR) photoacoustic gas sensor was developed by integrating three enhancing techniques: (a) boosting the excitation power up to 2 W via a custom-built large-mode erbium doped fiber amplifier (EDFA), (b) exploiting the acoustic resonance amplification of a hyperbolic nonlinear resonator (HNR), and (c) increasing the effective absorption path length by using a near-concentric multipass cavity (MPC) with 20 reflections. A weak CO absorption line at 1566.64 nm with the intensity of 2.074 × 10−23 cm/molecule was selected. The photoacoustic signal was enhanced 396 times. A minimum detection limit (MDL) of 190 ppb at 10 s was achieved and can be improved to be 11.4 ppb according to the Allan analysis, which was comparable to a mid-infrared (MIR) photoacoustic sensor. The ultra-enhanced NIR photoacoustic sensor is a cost-effective solution for the ppb-level trace gas detection, offering a price that is less than one-third that of MIR photoacoustic sensors.
Mina Mounir, Giuliano Bernardi, Toon van Waterschoot
Abstract Despite recent advances in audio technology, acoustic feedback remains a problem encountered in many sound reinforcement applications, ranging from public address systems to hearing aids. Acoustic feedback occurs due to the acoustic coupling between a loudspeaker and microphone, creating a closed-loop system that may become unstable and produce an acoustic artifact referred to as howling. One solution to the acoustic feedback problem, known as notch-filter-based howling suppression (NHS), consists in detecting and suppressing howling components hence stabilizing the closed-loop system and removing audible howling artifacts. The key component of any NHS method is howling detection (HD), which is typically based on the calculation of temporal and/or spectral features that allow to discriminate howling from desired audio signal components. In this paper, three contributions to HD research are presented. Firstly, we propose a novel howling detection feature, coined as NINOS $$^2$$ 2 -Transposed (NINOS $$^2$$ 2 -T), that exploits the particular time-frequency structure of a howling artifact. The NINOS $$^2$$ 2 -T feature is shown to outperform common state-of-the-art HD features, to be more robust to detection threshold variations, and to allow for the detection of early howling and ringing by discarding the often used concept of howling candidates selection. Secondly, a new annotated dataset for HD research is introduced which is significantly larger and more diverse than existing datasets containing realistic howling artifacts. Thirdly, a new HD performance evaluation procedure is proposed that is suitable when using HD features that do not rely on a howling candidates selection. This procedure opens the door for the evaluation of early howling and ringing detection performance and can handle the high class imbalance inherent in the HD problem by using precision-recall (PR) instead of receiver operating characteristic (ROC) curves.
Precise measurement of formaldehyde (H2CO) is a vital defense line for health, crucial for risk warning and prevention of major diseases like leukemia and cancer. The cross-interference of commercial electrochemical and metal oxide semiconductor sensors is grievous for H2CO sensing. Spraying disinfection alcohol, culinary steam, or even perfume may mistakenly trigger warnings. In this work, a low-cost 3D-printed differential photoacoustic cell (PAC) with a ultraviolet (UV) laser is developed for trace H2CO detection based on the photoacoustic spectroscopy (PAS) technology. A 3D-printed differential PAC is an integrated structure composed of two differential channels, two gas buffer chambers, a gas inlet and a gas outlet. Two steel tubes with identical length and an internal diameter of 4 mm are inserted into two differential channels to enhance the photoacoustic signal, respectively. Consequently, the differential PAC has a resonant frequency of 3775.5 Hz and a Q-factor of 27, with a minimal gas sample requirement of only 7.3 mL and a weight of 32.4 g. A 1σ detection limit of 1.03 ppm is achieved using a 320 nm 10 mW UV laser with an integration time of 1 s. An Allan-Werle deviation analysis indicates that the detection limit can be improved to 68.5 ppb at the optimal integration time of 969 s.
Priyankan Datta, Sreejesh Moolayadukkam, Rakesh Prasad Sahu
et al.
Sonodynamic therapy (SDT) is a minimally invasive targeted cancer therapy that uses focused low-intensity ultrasound (<10 MPa, <10 W/cm2) to activate sonosensitizer drugs. Once activated, these chemical compounds generate reactive oxygen species (ROS) to damage and kill cancer cells. A Phase I clinical trial has shown promising results for treating glioblastoma with SDT. We hypothesize that the efficacy of SDT can be improved by introducing lipid-coated microbubbles that produce a sonochemical effect that enhances ROS production. We investigate the hydrodynamics of a U.S. Food and Drug Administration (FDA)-approved microbubble, Lumason®, and a phospholipid-coated oxygen microbubble to predict the ultrasound parameters that induce sonoluminescence onset in biophysically relevant medium (e.g., water and blood) under clinical SDT conditions. The threshold pressures and frequencies for sonoluminescence with these therapeutic agents lie between 20 kHz – 1 MHz and 0.05 MPa – 1 MPa, respectively. The lipid-coated oxygen microbubble exhibits stronger sonoluminescence than the Lumason® microbubble, suggesting its use for improving SDT efficacy.
This paper proposes a novel microcone-curved resonant photoacoustic cell (MCR-PAC) for highly sensitive trace gas detection. The MCR-PAC features with microcone-curved resonant region and cylindrical buffer chamber, which dominates the photoacoustic signal amplification. By introducing the hyperbolic eccentricity as a new optimization dimension, the quality factor of the MCR-PAC is remarkably strengthened to enhance the acoustic pressure amplitude. At an eccentricity value of 5, the volume of the photoacoustic resonant cavity is approximately 0.23 cm3. Targeting trace acetylene, the system achieves a minimum detection limit of 1.41 ppb with an integration time of 290 s, corresponding normalized noise equivalent absorption coefficient is 1.88×10−9 W·cm−1·Hz−1/2. Compared to the traditional T-type PAC, the overall performance of MCR-PAC has been enhanced nearly fourfold. With its compact millimeter-scale dimensions and high sensitivity, the MCR-PAC demonstrates extensive potential for application in environmental monitoring and breath diagnostics.
Rodrigo Araya-Hermosilla, Jessica Martínez, César Zúñiga Loyola
et al.
This work focuses on a systematic method to produce Ag, Cu, and Ag/Cu metallic nanoparticles (MNPs) in situ assisted with ultrasound on cellulose paper. By tuning the concentration of AgNO3 and CuSO4 salt precursors and ultrasound time, combined with a fixed concentration of ascorbic acid (AA) as a reducing agent, it was possible to control the size, morphology, and polydispersity of the resulting MNPs on cellulose papers. Notably, high yield and low polydispersity of MNPs and bimetallic nanoparticles are achieved by increasing the sonication time on paper samples pre-treated with salt precursors before reduction with AA. Moreover, mechanical analysis on paper samples presenting well-dispersed and distributed MNPs showed slightly decreasing values of Young's modulus compared to neat papers. The strain at break is substantially improved in papers containing solely Ag or Cu MNPs. The latter suggests that the elastic/plastic transition and deformation of papers are tuned by cellulose and MNPs interfacial interaction, as indicated by mechanical analysis. The proposed method provides insights into each factor affecting the sonochemistry in situ synthesis of MNPs on cellulose papers. In addition, it offers a straightforward alternative to scale up the production of MNPs on paper, ensuring an eco-friendly method.
Tim Sidnell, Angel J. Caceres Cobos, Jake Hurst
et al.
The removal of per- and polyfluoroalkyl substance (PFAS) pollution from the environment is a globally pressing issue, due to some PFAS’ recalcitrant, bioaccumulative, and carcinogenic nature. Destruction via ultrasonic waves (sonolysis) is a promising contender for industrialisation due to; moderate power consumption, applicability to several PFAS and sample types, and limited by-products. Liquid flow rate through an ultrasonic reactor can affect the size, shape, and spatial distribution of ultrasonic cavities and hence their chemical activity. Such effects have not been studied during PFAS sonolysis, and temporal effects have not been studied much beyond the reactant concentration. Here, the effects of varying recirculating flow rate on the ultrasonic defluorination of perfluorooctane sulfonic acid (PFOS) and implications for industrial scale up are presented. Under the ultrasonic power (200 W L−1, 2.27 W cm−2) and frequency (410 kHz) used, flow rates of 79 and 214 ml min−1 enhanced defluorination up to 14 % during 30 min of treatment. However, these effects were temporal and most significant in the initial minutes of treatment. This indicated a dynamic bubble size distribution which stabilised after around 15 min. Defluorination rates of PFOS were compared with measured potassium iodide dosimetry, calorimetry, sonoluminescence (SL), and sonochemiluminescence (SCL). Flow rates which enhanced defluorination correlated moderately with enhanced SCL and negatively impacted SL, calorimetry, and dosimetry. Effects were attributed to perturbed cavity surfaces, leading to asymmetric cavity collapse, and the possibility of enhanced solvated electron production/interaction. SL, SCL, dosimetry, and calorimetric measurements were also temporal, and each showed different times to equilibrate. Flow rates of 439 and 889 ml min−1 returned all sonochemical measurements to the levels without flow, likely due to continued collapse temperature quenching by furthered bubble asymmetry. Flow also enhanced reactor cooling, which is significant for industrial temperature control. The pump energy consumed was small (≈1.9 %) compared to that of the amplifier and chiller, hence, PFOS defluorination was more cost-effective using flow. However, the effect may be limited for the longer treatment times needed for environmental remediation.
Acoustics play a central role in mankind’s interactions with the ocean and the life within. Passive listening to ocean “soundscapes” informs us about the physical and bio-acoustic environment from earthquakes to communication between fish. Active acoustic probing of the environment informs us about ocean topography, currents and temperature, and abundance and type of marine life vital to fisheries and biodiversity related interests. The two together in a multi-purpose network can lead to discovery and improve understanding of ocean ecosystem health and biodiversity, climate variability and change, and marine hazards and maritime safety. Passive acoustic monitoring (PAM) of sound generated and utilized by marine life as well as other natural (wind, rain, ice, seismics) and anthropogenic (shipping, surveys) sources, has dramatically increased worldwide to enhance understanding of ecological processes. Characterizing ocean soundscapes (the levels and frequency of sound over time and space, and the sources contributing to the sound field), temporal trends in ocean sound at different frequencies, distribution and abundance of marine species that vocalize, and distribution and amount of human activities that generate sound in the sea, all require passive acoustic systems. Acoustic receivers are now routinely acquiring data on a global scale, e.g., Comprehensive Nuclear-Test-Ban Treaty Organization International Monitoring System hydroacoustic arrays, various regional integrated ocean observing systems, and some profiling floats. Judiciously-placed low-frequency acoustic sources transmitting to globally distributed PAM and other systems provide: 1) high temporal resolution measurements of large-scale ocean temperature/heat content variability, taking advantage of the inherent integrating nature of acoustic travel-time data using tomography; and 2) acoustic positioning (“underwater GPS”) and communication services enabling basin-scale undersea navigation and management of floats, gliders, and AUVs. This will be especially valuable in polar regions with ice cover. Routine deployment of sources during repeat global-scale hydrographic ship surveys would provide high spatial coverage snapshots of ocean temperatures. To fully exploit the PAM systems, precise timing and positioning need to be broadly implemented. Ocean sound is now a mature Global Ocean Observing System (GOOS) “essential ocean variable”, which is one crucial step toward providing a fully integrated global multi-purpose ocean acoustic observing system.
Recognising a speaker's identity by the sound of their voice is important for successful interaction. The skill depends on our ability to discriminate minute variations in the acoustics of the vocal signal. Performance on voice identity assessments varies widely across the population. The neural underpinnings of this ability and its individual differences, however, remain poorly understood. Here we provide critical tests of a theoretical framework for the neural processing stages of voice identity and address how individual differences in identity discrimination mediate activation in this neural network. We scanned 40 individuals on an fMRI adaptation task involving voices drawn from morphed continua between two personally familiar identities. Analyses dissociated neuronal effects induced by repetition of acoustically similar morphs from those induced by a switch in perceived identity. Activation in temporal voice-sensitive areas decreased with acoustic similarity between consecutive stimuli. This repetition suppression effect was mediated by the performance on an independent voice assessment and this result highlights an important functional role of adaptive coding in voice expertise. Bilateral anterior insulae and medial frontal gyri responded to a switch in perceived voice identity compared to an acoustically equidistant switch within identity. Our results support a multistep model of voice identity perception.
María Teresa Tejedor Sastre, Olivier Louisnard, Christian Vanhille
In this paper we study the generation and behavior of subharmonics in a bubbly liquid confined in an acoustic resonator, through numerical simulations carried out at finite-amplitude acoustic pressure. Several configurations in terms of resonator length and driving frequency are considered here. Our results show that these frequency components, created from a higher-frequency signal at the source (ultrasound), are due to the nonlinearity of the medium at high acoustic-pressure amplitude and to the configuration of the resonator (geometry and boundaries). We also show that they have an amplitude-threshold dependence, which is in concordance with the literature. The response of these subharmonics to different sequences of pressure amplitudes also reveals the hysteretic nature of the bubbly liquid.
Nowadays Pickering emulsions have attracted immense attention due to their enhanced stability and numerous food applications. In this context, the present study was aimed to introduce Pickering emulsions stabilized by soy protein isolate (SPI)-maltodextrin (MD)-pectin complex incorporated with Himalayan walnut oil (HWO) for development of novel mayonnaise by ultrasound assisted emulsification. The functional mayonnaise was characterised for its stability, structural, textural, rheological and morphological properties. The rheological and microstructure measurements indicated that use of SPI-pectin HWO emulsions had a viscoelastic solid behaviour (G′ > G″) with highly interconnected gel-like network structure leading to diffused oil droplet distribution. An increase in particle size diameter (1.86–5.09 µm) and hardness values (43.16–69.08 N) was seen with increase in the SPI-pectin wall material concentration. A significant reduction in whiteness (L* value) from 91.12 to 53.52 was noted during storage for encapsulated samples. Mayonnaise formulations containing encapsulated HWO depicted significantly lower peroxide value (2.65 meqO2/kg) after extended storage period in comparison to free oil (8.33 meqO2/kg). FTIR analysis of mayonnaise formulations depicted successful complexation of HWO with SPI-MD-pectin matrix. These findings would be of immense importance in designing of Pickering emulsions stabilized by protein-polysaccharide particles with aim of delivering nutraceuticals associated with myriad health benefits.
Long-range propagation of sound pulses in the deep ocean is considered. A new method for the estimation of the pulse angular spectrum is presented. The method is based on the Husimi transform of a wave field and can be realized with a short vertical array of nondirectional hydrophones. As a result, one obtains a diagram of the arrival pattern in the time–angle plane. The method is applied to a model of the underwater sound channel in the Sea of Japan. Special attention is paid to sound scattering on a cold synoptic eddy along the waveguide. It is shown that the synoptic eddy leads to a splitting of the individual ray’s arrivals into clusters with close angles and times. The random sound-speed perturbation induced by internal waves blurs these clusters into a fuzzy background and simultaneously broaden the angular spectrum of pulses. Nevertheless, it is found that the latter effect is relatively weak for short vertical arrays. In particular, it is shown that increasing the array length from 10 to 30 m results in the separation of the arrivals with opposite angles.
Vowels are the most musical and sonic elements of speech. Previous studies found non-arbitrary associations between vowel intrinsic pitch and musical pitch in senseless syllables. In songs containing strings of senseless syllables, vowels are connected to melodic direction in close correspondence to their intrinsic pitch or the frequency of the second formant F2. This paper shows that also vowel intrinsic duration is related to musical patterns. It is generally assumed that low vowels like [a ɔ o] have a higher intrinsic duration than high vowels like [i y u] and that there is a positive correlation between the first formant F1 and duration. Analyzing 20 traditional Alpine yodels I found that vowels with longer intrinsic duration tend to align with longer notes, whereas vowels with shorter intrinsic duration with shorter notes. This new result might shed some light on size-sound symbolism in general: Since there is a direct match between vowel intrinsic duration and the “size” of musical notes, there is no need to explain the “size” of musical notes via Ohala's “frequency code” hypothesis. Moreover, I will argue that the iconic associations found between vowel acoustics and musical patterns support the idea of a sound-symbolic musical protolanguage. Such a protolanguage may have started with vowel syllables conveying pitch, timbre, as well as emotional, indexical, and sound-symbolic information.
Liquid atomization as a fluid disintegration method has been used in many industrial applications such as spray drying, coating, incineration, preparation of emulsions, medical devices, etc. The usage of ultrasonic energy for atomizing liquid is gaining interest as a green and energy-efficient alternative to traditional mechanical atomizers. In the past two decades, efforts have been made to explore new applications of ultrasonic misting for downstream separation of chemicals, e.g., bioethanol, from their aqueous solutions. Downstream separation of a chemical from its aqueous solutions is known to be an energy-intensive process. Conventional distillation is featured by low energy efficiency and inability to separate azeotropic mixtures, and thus novel alternatives, such as ultrasonic separation have been explored to advance the separation technology. Ultrasonic misting has been reported to generate mist and vapor mixture in a gaseous phase that is enriched in solute (e.g., ethanol), under non-thermal, non-equilibrium, and phase change free conditions. This review article takes an in-depth look into the recent advancements in ultrasound-mediated separation of organic molecules, especially bioethanol, from their aqueous solutions. An effort was made to analyze and compare the experimental setups used, mist collection methods, droplet size distribution, and separation mechanism. In addition, the applications of ultrasonic atomization in the production of pharmaceuticals and medical devices are discussed.
Rachel Pflieger, Geoffrey Audiger, Sergey I. Nikitenko
et al.
Knowledge on cavitation bubble size distribution, ambient radius of bubbles is of interest for many applications that include therapeutic and diagnostic medicine. It however becomes a hard quest when increasing the ultrasonic frequency, when direct observation of bubble dynamics is no longer possible. An indirect method based on the estimation of the bubble dissolution time under pulsed ultrasound (362 kHz) is used here under optimized conditions to derive ambient radii of cavitation bubbles in water saturated with He, Ar, Xe, O2, N2 and air: 3.0 µm for Ar, 1.2 µm for He, 3.1 µm for Xe, 2.8 µm for O2, around 1 µm for N2 and air. If the pulse on-time is increased, bubble coalescence occurs, the extent of which is rather limited for Ar but extremely high for He or N2.
Zero index materials where sound propagates without phase variation, holds a great potential for wavefront and dispersion engineering. Recently explored electromagnetic double zero index metamaterials consist of periodic scatterers whose refractive index is significantly larger than that of the surrounding medium. This requirement is fundamentally challenging for airborne acoustics because the sound speed (inversely proportional to the refractive index) in air is among the slowest. Here, we report the first experimental realization of an impedance matched acoustic double zero refractive index metamaterial induced by a Dirac-like cone at the Brillouin zone centre. This is achieved in a two-dimensional waveguide with periodically varying air channel that modulates the effective phase velocity of a high-order waveguide mode. Using such a zero-index medium, we demonstrated acoustic wave collimation emitted from a point source. For the first time, we experimentally confirm the existence of the Dirac-like cone at the Brillouin zone centre. Impedance mismatch between acoustic metamaterials and a surrounding medium hinders efficient applications, especially for zero-index materials. Here, Duboiset al. utilize the Dirac-like dispersion in a double-zero-index material to overcome this problem and to collimate sound.
The gender and anthropometric effects on vibration absorbed power characteristics of the seated body are investigated through measurements with 31 males and 27 females considering two different back support conditions, and three levels of vertical vibration (0.25, 0.50, and 0.75 m/s 2 rms acceleration) in the 0.5–20 Hz frequency range. The absorbed power responses for the males and females revealed strong gender effect, which could be mostly related to differences in body mass of the two groups. Subsequent analyses were conducted considering different datasets grouped corresponding to three ranges of the body mass-, build-, and stature-related parameters for both the males and females. Notable differences were evident in the absorbed power responses of the males and females with comparable anthropometric dimensions. Males revealed significantly higher peak and total absorbed power responses compared to the females of comparable anthropometric dimensions, except for the lean body mass. The differences, however, were relatively small in the data for males and females of comparable body mass. The peak power for the females, invariably, occurred at a lower frequency than that for the males. The total absorbed power responses revealed some degree of correlations with the body mass, lean body mass, body fat, and hip circumference ( r 2 >0.60), irrespective of the back support condition and excitation magnitude for both the genders.
Control engineering systems. Automatic machinery (General), Acoustics. Sound