Speed Of Sound Values Research Articles

Nutritional and bone health status in young men with mild-to-moderate intellectual disability and without intellectual disability residing in community setting in Malaysia.

This study aimed to compare the nutritional and bone health status between young men with mild-to-moderate intellectual disability and those without intellectual disability and to determine predictors for their bone health status. A total of 95 men (47 men with intellectual disability; 48 men without intellectual disability), aged 20-39years, participated in this study. Anthropometric profile, dietary intake, physical activity level and calcaneal speed of sound (SOS) were collected. The men with intellectual disability had moderate diet quality whilst the men without intellectual disability had poor diet quality. More participants with intellectual disability (97.9%) were inactive compared with their counterparts (10.4%). The SOS value was similar between groups and was lower than the reference. Increasing age and low physical activity level were negative predictors for bone health status. Both young men with and without intellectual disability have suboptimal nutritional and bone health status. Strategies to improve their nutritional and bone health status are warranted.

Superior stiffness and vibrational spectroscopic signature of two-dimensional diamond-like carbon nitrides

Abstract Carbon nitride materials are promising for applications in electronics, clean energy production, and heat dissipation. Two-dimensional (2D) diamond-like carbon nitrides α -C 2 N 2 , β -C 2 N 2 , and γ -C 4 N 4 rise as beyond graphene semiconductors. Here, we apply first-principles calculations and group theory to study their structure, mechanical properties, and vibrational signature. The α -C 2 N 2 is the strongest among them, with a 2D Young’s modulus E 2D equal to 616(6) N/m, followed by the γ -C 4 N 4 with an E 2D equal to 632(6) N/m and 581(7) N/m along its zigzag and armchair directions, respectively, and the β -C 2 N 2 with an E 2D equal to 582(9) N/m. These materials are about 2 times stiffer than graphene, and are the stiffest among 2D networks of carbon and nitrogen atoms. The zigzag direction of 2D γ -C 4 N 4 is approximately 8% stronger than its armchair direction, unusual for in-plane anisotropic 2D materials, where the armchair direction is considerably weaker than the zigzag direction. These findings from stress–strain analysis are consistent with the high sound speed and elastic constants values we found by using 2D density-functional perturbation theory framework, suggesting them for mechanical reinforcement. We report the phonon wavenumber, atomic vibrational pattern, and Raman and infrared spectra for all polytypes. The longitudinal and transverse optical modes of the in-plane isotropic polytypes display the breakdown of LO–TO splitting, characteristic of 2D polar crystals. We found that the difference between their phonon wavenumbers can be probed in their unpolarized Raman and infrared spectra. The simulated angular dependency of the Raman intensity under backscattering parallel and cross polarizations show how to assign the A 1 ′ and E ′ modes of the α -C 2 N 2 , the A 1 g and E g modes of the β -C 2 N 2 , and of the A g and B 1 g modes of the γ -C 4 N 4 , being key for polytype identification. These results provide comprehensive information on the emerging 2D diamond-like carbon nitrides, necessary for further developments on their synthesis, characterization, and future device fabrication.

White dwarfs as a probe of dark energy

We investigate the radial density distribution of the dynamical dark energy inside the white dwarfs (WDs) and its possible impact on their intrinsic structure. The minimally-coupled dark energy with barotropic equation of state which has three free parameters (density, equation of state and effective sound speed) is used. We analyse how such dark energy affects the mass-radius relation for the WDs because of its contribution to the joint gravitational potential of the system. For this we use Chandrasekhar model of the WDs, where model parameters are the parameter of the chemical composition and the relativistic parameter. To evaluate the dark energy distribution inside a WD we solve the conservation equation in the spherical static metric. Obtained distribution is used to find the parameters of dark energy for which the deviation from the Chandrasekhar model mass-radius relation become non-negligible. We conclude also, that the absence of observational evidence for existence of WDs with untypical intrinsic structure (mass-radius relation) gives us lower limit for the value of effective sound speed of dark energy $c_s^2 \gtrsim 10^{-4}$ (in units of speed of light).

Tibial speed of sound changes in preterm infants during the first year of life.

Metabolic bone disease of prematurity (MBD) frequently affects preterm infants. The accurate diagnosis of the MBD remains a challenging issue despite characteristic clinical, laboratory and imaging features. Recently, non-invasive quantitative ultrasound (QUS) measuring speed of sound (SOS) has been applied to assess bone status. Limited data are available on comparison of QUS among preterm infants. To evaluate development of tibial bone SOS values in preterm infants during the first year of life and compare the SOS values among different birth weight categories. QUS was used in 153 infants below 34 weeks of gestation. The study group was divided into 3 subgroups based on birth weight (BW): ≤1000 g, 1001-1500 g and >1500 g. SOS measurement was performed at 6 and 12 months of corrected age (CA). Overall, we found significant increase in mean tibial SOS between 6 and 12 months of CA (3004 ± 123 vs 3253 ± 109 m/s, p = 0.001). There were significant differences in SOS among birth weight categories at 6 months of CA (p = 0.045). However, these differences were not statistically significant at 12 months of CA (p = 0.289). The infants ≤ 1000 g scored the highest SOS values at both time points. Tibial SOS significantly increases during infancy in preterm newborns. Significant variation exists in SOS at 6 months, but not at 12 months of corrected age according to BW. Moreover, inverse correlation between BW and SOS indicating better bone status was revealed in extremely low birth weight infants at both 6 or at 12 months of CA.

The sound absorption properties of highly porous silicon nitride ceramic foams

The sound absorption properties of highly porosity Si3N4 ceramic foams was studied and the effect of structural factors such as porosity, pore size and thickness of Si3N4 ceramic foams and the air gap backing on the sound absorption properties was systematically investigated. The results showed that the higher porosity and smaller pore size of Si3N4 ceramic foams would contribute to better sound absorption in almost entire frequency. While the thicker samples would increase the sound absorption coefficient in low frequency by shifting the sound absorption peak to lower frequency. By inserting an air gap and adjusting the pore size of Si3N4 ceramic foams, a selectively filtration of low or medium frequency could be achieved. The values of sound speed and acoustic impedance of the Si3N4 ceramic foams were notably low and decreased along with the increase of porosity.

DIY small scale resonance tube for measuring the speed of sound in air

This research invented a small scale with no cost experimental set to determine the speed of sound in the air by resonance method. Equipment consisted of a bubble tea straw with label measuring scale, a full plastic water bottle and the n-Track Tuner (iOS) or Guitar Tuner (Android) application for generating sound waves. Sound waves were sent down a bubble tea straw filled with an air. The waves reflected back up the straw from a water surface and interfered with the waves traveling downward. By properly adjusting the water level, a resonance condition could be established. By knowing the frequency of the sound wave and the position of the water level for two different resonant lengths, the speed at which sound waves travel through the air was found. In this experiment, the frequency was specified 1, 500 Hz at 24.00 °C, 26.00 °C and 30.00 °C respectively. The sound speed which was calculated was 345.0, 347.0 and 349.0 m/s respectively. The standard value of sound speed at the same temperature was 345.4, 346.6 and 349.0 m/s respectively. The percent error value of the sound speed was calculated to compare with the standard value of sound speeds was 0.1%, 0.1% and 0.0% respectively. This an experiment was effective and could be efficiently used in educational physics. Moreover, it is easy to use, low cost, and portable. Students can also prepare the equipments themselves.

Mechanical Weakness of Thoracic Aorta Related to Aging or Dissection Predicted by Speed of Sound with Collagenase

Scanning acoustic microscopy reveals information on histology and speed of sound (SOS) through tissues. Slower SOS corresponds to lower stiffness. The aim of the present study was to investigate whether SOS values reflect the degree of degeneration with aging or dissection and whether enzymatic digestion susceptibility is distinct. The SOSs of media other than the atheromatous areas of normal and surgical dissections were measured and compared using medial degeneration grade (MDG) scores. To evaluate the damage rate, SOS was assessed after collagenase digestion. SOS scores negatively correlated with aging and MDG scores. Dissected aortas had higher SOS and MDG scores without age correlation. Collagenase digestion was present in all aortas, but older aortas were more injured than younger aortas. Dissected aortas were more vulnerable to collagenase. Older and dissected aortas expressed specific extracellular matrix components to compensate for mechanical weakness. The present method can evaluate mechanical weakness corresponding to histology to investigate the cause of rupture.

Maximum Entropy Derived Statistics of Sound-Speed Structure in a Fine-Grained Sediment Inferred From Sparse Broadband Acoustic Measurements on the New England Continental Shelf

Marginal probability distributions for parameters representing an effective sound-speed structure of a fine-grained sediment are inferred from a data ensemble maximum entropy method that utilizes a sparse spatially distributed set of received pressure time series resulting from multiple explosive sources in a shallow-water ocean environment possessing significant spatial variability of the seabed. A remote sensing seabed acoustics experiment undertaken in March 2017 off the New England Shelf was designed so that multiple independent analyses could infer the statistical properties of the seabed. The current analysis incorporates the measured horizontal variability from interpretations of a subbottom profiling survey of the experimental area. An idealized range- and azimuth-dependent parameterization of the seabed is derived from identification of horizons within the seabed that define multiple sediment layers. A sparse set of explosive charges were deployed on circular tracks with radii of about 2, 4, and 6.5 km with an acoustic array at the center to correlate a set of random measurements to physical acoustic processes that characterize the seabed. The mean values of a surface sound speed ratio and a linear sound speed gradient for the fine-grained sediment layer derived from 12 data samples processed in the 25-275-Hz band provide an estimate of the effective sound-speed structure in a 130-km <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> area. The inferred sediment sound speed values are evaluated by predicting measured time series data not used in the statistical inference, and are also compared to historical measurements. Finally, the low-frequency maximum entropy estimate of the sediment sound speed along with physical measurements derived from piston core measurements are utilized to estimate the sediment grain bulk modulus.

Estimates of Low-Frequency Sound Speed and Attenuation in a Surface Mud Layer Using Low-Order Modes

Whereas there have been numerous theoretical and experimental studies on the properties of marine granular sands, there are significantly fewer studies on sediments classified as muds. The validity of geoacoustic models for muddy sediments has not been successfully tested due to the lack of inverted low-frequency sound speed and attenuation values. The geoacoustic properties of a surface fine-grained mud layer, overlaying three sand transition layers, and a half-space basement within the New England Mud Patch, were studied using explosive signals from long-range along-shelf sound propagation tracks. The sound-speed profile of the mud layer in the low-frequency band (100-500 Hz) was estimated using acoustic normal mode characteristics including the mode shapes and the modal dispersion curves of low-order modes, which mainly propagated in the water column and the surface mud layer. The ambiguity of sound speed at the top of the mud layer and sound-speed gradient was approximately removed. It was found that the resultant sound-speed ratio at the water-sediment interface was close to unity and the sound-speed gradient was 1.8 1/s with a standard deviation of 1.0 1/s. The attenuation in the mud layer was inverted using the attenuation coefficient of the first mode extracted from explosive signals at three source locations. The estimated attenuation at 150 Hz had a mean of 0.006 dB/m and a standard deviation of 0.003 dB/m.

The Effect of Daily Exercise Program on Bone Mineral Density and Cortisol Level in Preterm Infants with Very Low Birth Weight: A Randomized Controlled Trial

PurposeThis randomized controlled double-blinded experimental study was carried out to determine the effects of the daily exercise program on bone mineral density and cortisol level in preterm infants with VLBW matched for birth weight, gestation week, and gender. Design and methodsThe study was carried out with preterm infants (n = 24) hospitalized in the NICU of a tertiary hospital. Ethical committee approval, institutional permission, parental written consent were obtained. A daily exercise program was implemented in preterm infants in the exercise group for 30 days, once a day, and continuing for 7–10 min. Before and after the study the following were evaluated in preterm infants in the exercise and control group: anthropometric measurements, tibia speed of sound (SOS) for bone mineral density, serum cortisol levels. ResultsSerum cortisol levels (p = 0.05) were decreased, bone SOS values in the exercise group were increased (p = 0.009), after the study. The difference between pre-, post-study bone SOS and serum cortisol values of infants in the exercise group were high (p > 0.05). Percentage increases in anthropometric values in the exercise group were higher than the control group after the study (for all; p > 0.05). ConclusionsThe daily exercise program has positive effect on bone SOS and serum cortisol values in preterm infants. Neonatal nurses can implement the daily exercise program in clinical practice.Trial registration numberClinicaltrials.govNCT03773679.

PRELIMINARY EVALUATION OF ATMOSPHERIC TEMPERATURE AND WIND PROFILES OBTAINED USING UNMANNED AERIAL VEHICLE BASED ACOUSTIC TOMOGRAPHY

Abstract. An acoustic signature generated by an unmanned aerial vehicle is used in conjunction with tomography to remotely sense temperature and wind profiles within a volume of atmosphere up to an altitude of 120 m and over an area of 300 m × 300 m. Sound fields recorded onboard the aircraft and by an array of microphones on the ground are compared and converted to sound speed estimates for the ray paths intersecting the intervening medium. Tomographic inversion is then used to transform these sound speed values into three-dimensional profiles of virtual temperature and wind velocity, which enables the atmosphere to be visualised and monitored over time. The wind and temperature estimates obtained using this method are compared to independent measurements taken by a co-located mid-range ZephIR LIDAR and sensors onboard the aircraft. These comparisons show correspondences to better than 0.5 °C and 0.3 m/s for temperature and wind velocity, respectively.

Hydrodynamic processes in fused quartz under the action of laser radiation

The paper analyzes numerically the hydrodynamic processes developing inside the fused quartz under the action of intense laser impulses. Depending on laser intensity two basic regimes are obtained and described in details. At low intensities, the slow regime driven by the heat transfer is observed. Herewith, the fracture took place in the heated region before the phase transition. At higher intensities, the high-speed propagation regime is established characterized by the fracture events exactly at the interfacial boundary between the hot plasma and condensed phase. The propagation of absorption wave coupled with the fracture wave is limited by the value of sound speed in the hot plasma, which determines the expansion of plasma into the spallation region ahead of the absorption front. The proposed model of the process agrees well with the recent experimental data, in particular with the characteristic velocity scales.

Investigation on molecular interaction of glycols in methanol solutions of methylparaben (methyl 4 – hydroxybenzoate) at different temperatures through thermo-acoustical analysis

To determine the nature of interaction of ethylene glycol (EG), propylene glycol (PG), and hexylene glycol (HG) in the methanol solutions of methylparaben, density and speed of the sound of ethylene glycol, propylene glycol, and hexylene glycol in methylparaben–methanol (MePB–MeOH) solutions were investigated at different temperatures (from 293.15 to 308.15 K) and at the pressure, p = 0.1 MPa. The computed density and speed of sound values were utilized to determine the apparent molar volume and apparent molar isentropic compressibility of glycols in the binary solvent. The apparent molar volume Vϕ0 and apparent molar isentropic compressibility Kϕ, s0 at infinite dilution for all the ternary system were computed at all working temperatures. The limiting partial molar volume Vϕ0 increases with temperature and indicates that the solute–solvent interaction for HG in methanol solutions of MePB are stronger than EG and PG in methanol solutions of MePB. The positive values of apparent molar expansibility at infinite dilution, signify the existence of solute–solvent interaction in the inspected system. The isentropic compressibility, βs for the present studied system, increases with increase in temperature. The negative Kϕ, s0 values, for the investigated ternary systems, can be attributed to the predominance of penetration effect over solvent intrinsic compressibility.

Microstructure Detection by Scanning Acoustic Microscope (SAM) using Special and Antigen Staining

ObjectiveA SAM detects and visualizes cellular components and extracellular matrix (ECM) proteins. However, which materials contribute to the values of speed‐of‐sound (SOS) or attenuation‐of‐sound (AOS) is unknown. SOS and AOS indicate tissue stiffness or softness because greater SOS and AOS areas correspond to stiffer portions of tissues. The aim of this study is to clarify the role of each component in SAM observation.MethodsTo detect each component, special staining for ECM and cellular components such as collagen, elastin and DNA were used. To recognize specific antigens, immunostaining with Ni‐DAB solution as horseradish peroxidase substrate was applied. SAM images before and after staining were compared.ResultsFor nuclear detection, both hematoxylin and Giemsa staining resulted in increased SOS and AOS values of the nuclei (Fig. 1 and Fig. 2). To distinguish ECM components, aniline blue (Fig. 3) and Sirius red for collagen and resorcin‐fuchsin (Fig. 4) for elastin stained well to increase SOS and AOS values according to duration of incubation. After collagenase digestion, SOS and AOS values at the positive‐staining areas decreased. Immunostaining with Ni‐DAB solution raised SOS and AOS values of antigen location (Fig. 5).ConclusionsSpecial and immunostaining used in light microscopy are also available to certain the antigen location for SAM. Collagens and smooth muscles contribute to raise the values of SOS and AOS.Support or Funding InformationThe study was supported by a grant from the Japan Society for the Promotion of Science KAKENHI, Scientific Research Grant Number (c) 15K08375. There are no conflicts of interest to declare.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Breast Cancer Assessment With Pulse-Echo Speed of Sound Ultrasound From Intrinsic Tissue Reflections: Proof-of-Concept.

The aim of this study was to differentiate malignant and benign solid breast lesions with a novel ultrasound (US) technique, which measures speed of sound (SoS) using standard US transducers and intrinsic tissue reflections and scattering (speckles) as internal reference. This prospective, institutional review board-approved, Health Insurance Portability and Accountability Act-compliant prospective comparison study was performed with prior written informed consent from 20 women. Ten women with histological proven breast cancer and 10 with fibroadenoma were measured. A conventional US system with a linear probe was used for SoS-US (SonixTouch; Ultrasonix, Richmond, British Columbia, Canada). Tissue speckle reflections served as a timing reference for the US signals transmitted through the breasts. Relative phase inconsistencies were detected using plane wave measurements from different angular directions, and SoS images with 0.5-mm resolution were generated using a spatial domain reconstruction algorithm. The SoS of tumors were compared with the breast density of a larger cohort of 106 healthy women. Breast lesions show focal increments ΔSoS (meters per second) with respect to the tissue background. Peak ΔSoS values were evaluated. Breast carcinoma showed significantly higher ΔSoS than fibroadenomas ([INCREMENT]SoS > 41.64 m/s: sensitivity, 90%; specificity, 80%; area under curve, 0.910) and healthy breast tissue of different densities (area under curve, 0.938; sensitivity, 90%; specificity, 96.5%). The lesion localization in SoS-US images was consistent with B-mode imaging and repeated SoS-US measurements were reproducible. Using SoS-US, based on conventional US and tissue speckles as timing reference, breast carcinoma showed significantly higher SoS values than fibroadenoma and healthy breast tissue of different densities. The SoS presents a promising technique for differentiating solid breast lesions.

Hugoniot Measurements Utilizing In Situ Synchrotron X-ray Radiation

Pressure–density relationships derived from the experimentally obtained shock and particle velocities are critical to define a material’s equation of state (EOS). Typically, impact experiments coupled with velocimetry are used to map a material’s Hugoniot. Limitations such as sample geometry and varying indices of refraction may prevent proper characterization using traditional techniques such as photon doppler velocimetry (PDV) or velocity interferometer system for any reflector (VISAR). Here, traditional Hugoniot measurements using PDV are compared to dynamic x-ray imaging encompassing two different sample geometries on the gas gun platform. Through each of these methods an experimentally derived Hugoniot is determined for a previously uncharacterized polymeric material, Somos Watershed XC11122, that is used 3D printed stereolithography parts. A Us–up relationship was determined to be Us = 2.93 us + 1.73 mm/μs through traditional PDV. Slope and sound speed values determined from x-ray imaging methods varied 11% from PDV measurements. Each method yielded a Hugoniot with densities similar to poly(methyl methacrylate) (PMMA). The similarity shows the viability of such analyses for dynamic properties and Hugoniot data. The performance and analysis of both PDV and dynamic x-ray measurements are laid out in this work. Comparing PDV and x-ray imaging highlights distinct advantages and disadvantages among each method. PDV provides less uncertainty for velocity measurements, however x-ray imaging is more spatially resolved allowing for shock steadiness observations of value when studying heterogeneous materials. Additionally, x-ray imaging provides greater insight into the shape and heterogeneity of the shock front as well as uniaxial strain state (1D zone) assumptions.

Association between speed of sound of calcaneal bone assessed by quantitative ultrasound and sarcopenia in a general older adult population: A cross-sectional study

BackgroundLower calcaneal speed of sound may be related to sarcopenia because sarcopenia and osteopenia/osteoporosis show a linked relationship in older adults. The purpose of this study is to clarify whether the speed of sound of calcaneal bone assessed by quantitative ultrasound is associated with sarcopenia in a community-dwelling older adult population. MethodsThis was a cross-sectional observational study. The participants in the study were recruited from a group of individuals who had registered for an annual town-sponsored medical check-up. The inclusion criteria for participation in the study were (1) aged older than 40 years, (2) living independently, and (3) able to walk without assistance. Those who had nursing care insurance were excluded. Four hundred sixty-seven residents (182 men, 285 women) were registered in the study. Demographic information, fall history, muscle mass index, grip strength, and gait speed were assessed. The speed of sound through the calcaneal bone was evaluated using a CM-200 sonometer. The assessment for sarcopenia is based on the recommendations of the Asian Working Group for Sarcopenia. ResultsSpeed of sound was positively correlated with muscle mass index and gait speed in men, and was positively correlated with grip strength and gait speed in women, when adjusted for age and body mass index. In a multivariate logistic regression analysis adjusted for age and sex and other confounders, speed of sound was independently related with lower gait speed and sarcopenia in women. Speed of sound under 1470.5 m/sec had discriminated for sarcopenia in females. ConclusionWe propose that the speed of sound of calcaneal bone may be used to screen for sarcopenia in women. Sarcopenia should be considered if the speed of sound value is less than 1470.5 m/s in older women.

Determining the Speed of Sound as a Function of Temperature Using Arduino

When sound waves are taught at the secondary level, the speed of propagation of sound is one of the most important characteristics to be analyzed. However, it is very common in textbooks that the value of sound speed in air is considered constant regardless of the experimental conditions. The great question is that since sound is a mechanical wave, its speed is influenced by the medium of propagation and also by the temperature. In most cases, the techniques reported for that goal usually make use of expensive equipment and techniques that may not be affordable and/or easy to implement in schools, which is an experimental limitation for the teachers to show this influence on their students. In this work, we present a low-cost experimental apparatus, controlled by the open source electronic platform Arduino®, with which it is possible to determine the speed of propagation of sound as a function of the temperature for a short measuring region, thus enabling the students to verify experimentally this important feature of sound waves.

Determination of Ultrastructural Properties of Human Carotid Atherosclerotic Plaques by Scanning Acoustic Microscopy, Micro-Computer Tomography, Scanning Electron Microscopy and Energy Dispersive X-Ray Spectroscopy

Microcalcification is the precursor of vulnerability of plaques in humans. Visualization of such small structures in vivo with high spatial resolution is an unsolved issue. The goal of this study is to evaluate the potential of scanning acoustic microscopy (SAM) in the determination of atherosclerotic plaques with calcifications by validating this technique with micro-computer tomography (micro-CT), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The fibrocalcific plaques were obtained from 12 different patients and initially examined with micro-CT. The images exhibited calcifications within these plaques. For imaging with SAM, approximately 5 μm thick slices were prepared. Sound speed values within calcified regions were measured to be greater than the ones in collagen-rich regions. These fibrocalcific plaques were also examined with SEM and EDS revealing collagen and calcium deposition within these samples. The consistency of the results obtained by all of the modalities involved in our study is an indication of the potential of SAM as a clinical tool for the diagnosis of vulnerable plaques.

Ultrasonic parameter measurement as a means of assessing the quality of biodiesel production

Whilst fossil fuels have been an industrial driver for many decades, environmental concerns related to global warming have driven the development of alternative energy sources, such as the generation of biodiesel from vegetable oils. For a biodiesel to be commercialised, it must meets property and quality requirements from International Standards. Most of these checks must be performed off-line, with significant costs in terms of shutdown time and testing. On the other hand, ultrasound measurement can provide an in-line monitoring tool to assess the advance of transesterification. Although this was highlighted in previous works, hitherto this has not been the subject of a detailed metrological approach to define the uncertainty associated with ultrasound techniques applied to biodiesel and related liquids. This paper presents such research and addresses measurement of two ultrasound parameters, Speed of Sound (SoS) and attenuation coefficient (Att), and their capability of assessing macroscopic characteristics of the biodiesel. The liquids tested were pure edible oils (vegetable, corn, and sunflower), castor oil, pure biodiesel (B100), as well as blends of biodiesel with common contaminants or by-products related to biodiesel transesterification. Details of the biodiesel manufactured were varied, using different stirring speeds of rotation (200 rpm and 550 rpm), temperatures (40 °C and 50 °C), and KOH catalyst concentrations (0.2% and 1.5%). Contaminants added to pure biodiesel were methanol (0.10% and 0.20%), glycerol (0.10% and 0.15%) and triglyceride (2%). The acoustic characteristics of these liquids were determined relative to water using a broadband through-transmission substitution method covering the frequency range 1–20 MHz. Normalized error analysis has been applied to assess the equivalence of experimental results, as well as to discriminate the detection sensitivity of the technique. From the measurements, all edible oils showed equivalent experimental values for SoS and Att over the usable frequency band 2 MHz to 18 MHz. In contrast, biodiesel produced from sunflower and different reaction routes led to SoS and Att which were statistically different over the same frequency range, reflecting the ability of ultrasound to monitor low-level contamination of different blends. Finally, the paper concludes that ultrasound shows promise as a means of assessing biodiesel quality and purity with sensitivity sufficient to discern contaminants in a proportion as low as 0.1% in mass for Att measurements.