James Greenleaf – jfg@mayo.edu Mayo Clinic – Department of Radiology, Rochester, MN 55905, USA
Popular version of paper 1aBAd1: Guided wave inversion for arterial stiffness Presented Monday morning, December 7, 2020 179th ASA Meeting, Acoustics Virtually Everywhere
Cardiovascular disease is a leading cause of death in the United States and worldwide. Atherosclerosis, or the stiffening of arteries, contributes to damage of downstream organs such as the brain and heart. If early atherosclerosis can be identified, it may be treated. Our research is motivated by developing a diagnostic tool for early detection of atherosclerosis using one of the cheapest and safest modalities, medical ultrasound, which can used widely across the world.
The target for this work is on estimating the stiffness and other mechanical properties of the carotid artery, a well-known indicator of cardiovascular disease. To accomplish this aim, we use a technique called shear wave elastography, where the wave propagation characteristics measured in the arterial wall are used to estimate the stiffness of the artery. Specifically, we use acoustic radiation force, resulting from focused ultrasound waves from an ultrasound probe to tap on the wall of the artery. This tap creates waves that travel within the artery wall, which are also measured with the same ultrasound probe. In this work, we present algorithms that convert the wave motion measured with ultrasound to values of arterial stiffness.
Mike Raley – mike.raley@ecoreintl.com Ecore International 715 Fountain Avenue Lancaster, PA 17601
Popular version of paper 1aAAa2 Presented Monday morning, December 7, 2020 179th ASA Meeting, Acoustics Virtually Everywhere
Hospitals are noisy places. The Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) surveys patients’ perception of their hospital care. Consistently, the quietness of the hospital is one of the lowest scores in the survey. If you have ever spent time in a hospital, that is likely no surprise.
What might be surprising is that a recent study by Bliefnick et al. showed that the acoustic metrics we typically use to evaluate noise in hospitals are not well-correlated with HCAHPS scores. Interestingly, they found that peak occurrence rates, how often a loud sound was above a certain threshold, were well-correlated with HCAHPS scores. In another recent study, Park et al. found that footsteps were a top five contributor to perceived loudness peaks, noise events that are significantly louder than the sound level before and after the event. Along with anecdotal evidence from healthcare designers, these two studies indicate that footsteps could contribute to a patient’s perception of quietness, and reducing noise from footsteps could improve that patient experience.
Test standard ASTM E3133 measures floor impact sound radiation in the space where the impact occurs. This differs from the common impact insulation class (IIC) standard (ASTM E492) that measures impact sound in the room below where the impacts occur.
Using ASTM E3133 we can compare floor impact sound levels for flooring common to hospitals, such as VCT and standard sheet vinyl, as well as specialty acoustical flooring like sheet vinyl fusion bonded to a rubber backing (Vinyl Rx).
Figure 2 shows that the Vinyl Rx can significantly reduce floor impact radiated sound, with a 13dB reduction in the overall sound level compared to VCT (a ~60% reduction in perceived loudness). The significant reduction in impact sound levels gives us an exciting indicator that specialty acoustical flooring has the potential to reduce predicted loudness peaks and improve the patient experience.
Unfortunately, there are some issues with the ASTM test method that limit its usefulness. In the course of testing to ASTM E3133, we uncovered substantial variation in the sound levels measured using two standard tapping machines from different manufacturers. The variation in tapping machines is evident even on a loud floor like concrete (see Figure 3).
The standard has provisions to account for the self-noise of the tapping machine, but those provisions do not correct the discrepancy between the two machines. Further investigation has shown that different flooring actually changes the self-noise of the tapping machine, so it cannot be easily accounted for.
While it may be possible to modify tapping machines to address the variation in self-noise, the most likely solution to the problem is a different impact source. Impact sources like golf balls, cue balls, and ball bearings can create consistent impacts without the self-noise issues of standard tapping machines. These objects are also readily available and easily transportable, so they lend themselves well to field measurements.
Work carried out by researchers from ÉTS and the IRSST
Bastien Poissenot-Arrigoni – bastien.poissenot.1@ens.etsmtl.ca Olivier Doutres – olivier.doutres@etsmtl.ca École de Technologie Supérieure 1100 Rue Notre-Dame Ouest, Montréal, QC H3C 1K3
Franck Sgard – franck.sgard@irsst.qc.ca Chun Hong Law – chunhonglaw@hotmail.com 505 Boulevard de Maisonneuve O., Montréal, QC H3A 3C2
Popular version of paper 5aNSa4 (Earcanal anthropometry analysis for the design of realistic artificial ears) Presented Friday morning, December 11, 2020 179th ASA Meeting, Acoustics Virtually Everywhere
Noise exposure accounts for 22% of worldwide work-related health problems. Excessive noise not only causes hearing loss and tinnitus, but also increases the risk of cardiovascular diseases. To provide protection, workers normally wear earplugs. However, commonly available earplugs are often uncomfortable, since they don’t fit everyone’s ears equally well.
How could we improve the comfort and effectiveness of these earplugs? What aspects of the ear canal must be taken into account? To answer these questions, researchers from the École de technologie supérieure (ÉTS University) and the Institut de recherche en santé et sécurité du travail (IRSST) analyzed the varying structure of ear canals to find a correlation between their shapes and the effectiveness of three commonly-used models of earplugs.
Each one is unique Just like fingerprints, ear canals are unique. So, to find the best compromise between comfort and efficiency, you need to understand the relationship between the shapes of ear canals and of earplugs.
Earplugs must not only fit properly inside the ear canal, but must also exert pressure against the walls of the canal in order to make a tight seal. However, if the plugs put too much pressure on the ear canal walls, they will cause the wearer pain.
The methodology To study these aspects, 3D models of volunteer workers’ ear canals were created. These people wore three different types of earplugs. To obtain the geometry of their ear canals, a moulding material was injected to create canal moulds. These moulds were then scanned by measurement software to establish the geometric characteristics of the ear canal, such as the width at various locations and the overall length. The noise attenuation of the three models of earplugs was then measured for each volunteer. Two miniature microphones were installed in and around the plugs to measure the noise outside and inside the ear plug.A statistical analysis as well as algorithms based on artificial intelligence helped categorize the morphology of ear canals as a function of the degree of noise mitigation of each earplug. Concrete applications The results of the study show that the area of the ear canal called the “first bend” is closely linked to noise attenuation by earplugs. Groups of similar structures created using artificial intelligence will allow researchers to develop a multitude of tools for manufacturers, who will then be able to produce a range of more comfortable ear plugs. This will allow prevention professionals to suggest models suited to each worker’s ear canals.
Washington University in St. Louis 4511 Forest Park Ave St. Louis, MO 63108
Popular version of paper 3pBAb1 Presented Wednesday afternoon, December 9, 2020 179th ASA Meeting, Acoustics Virtually Everywhere
Brain cancer diagnosis starts with magnetic resonance imaging, or MRI, which allows clinicians to locate a tumor in the patient’s brain. However, MRI only provides anatomic information about the brain tumor. To understand the tumor type and to make a decision about future treatment, a neurosurgeon performs a tissue biopsy, drilling a small hole in the skull and carefully extracting a tumor sample with a long hollow needle. Liquid biopsy uses a blood sample to achieve similar information as the brain biopsy, without the need for surgery.
Unlike other cancers, whose small biomarkers, such as DNA, can be found circulating in a patient’s blood, brain cancers are separated from the rest of the body by the blood-brain barrier that does not allow tumor DNA to seep into the blood circulation. Two technologies are combined to briefly open the barrier: focused ultrasound and microbubbles. Focused ultrasound uses low-frequency ultrasonic energy to target tumors deep in the brain. Microbubbles are tiny gas bubbles commonly used in ultrasound imaging. When microbubbles are injected into a blood vessel, they travel along the blood flow to all parts of the patient’s body, including the brain. Once at the brain tumor, focused ultrasound causes the bubbles to expand and contract against the blood vessels in the brain, disrupting the blood-brain barrier and opening a door for the tumor DNA to be released into the blood circulation.
Video demonstrating the sonobiopsy technique to diagnose brain cancer.
The research presented here proves the success of sonobiopsy in increasing the levels of brain tumor biomarkers in the blood for the diagnosis of the most common and deadly brain tumor, glioblastoma, with different biomarker types and animal models. Sonobiopsy was optimized by increasing the amount of ultrasonic energy and the number of microbubbles injected to improve the number of biomarkers released in a mouse model. The utility of sonobiopsy was extended to different sized tumors and may be more effective for larger tumors, as demonstrated in a rat model. The potential for clinical translation was demonstrated by enhancing the release of brain-specific biomarkers in a pig model, with similar skull thickness as humans.
Sonobiopsy may be integrated into future clinical practice as a complement to MRI and tissue biopsies as an approach to noninvasively acquire molecular information of the tumor. The potential impact can be for the diagnosis of not only brain tumors but all other brain diseases. There are more studies to be done to better understand and optimize the technology before its practical value in humans, but this presentation is a step towards the future of brain cancer diagnosis.
Laboratorio de Ecologia Molecular de Vertebrados Marinos Universidad de los Andes Bogotá, Colombia
Popular version of paper 3aAB2 Presented Wednesday morning, December 9 , 2020 179th ASA Meeting, Acoustics Virtually Everywhere
Growing ship traffic worldwide has led to a relatively recent increase in underwater noise, raising concerns about effects on marine mammal communication. Many populations of several dolphin species inhabit the eastern Pacific Ocean, particularly along the Chocó coast of Colombia. Recent research has confirmed that anthropologic noise pollution levels in this region are one of the lowest in any studied area around the globe, allowing an opportunity for scientists to listen and analyze a relatively undisturbed soundscape in our oceans.
Figure 1. Vessel traffic in the Americas (a) and in (b) Colombia in particular. Red indicates high traffic and blue areas have no traffic. Note the gap in traffic in the Colombian Pacific coast where the Gulf of Tribugá is located (inside black/red box) as compared to all other coastal regions.
Currently, the CPC is slated for the construction of a port in the Gulf of Tribugá, pending permits. Previous port construction projects in other countries have shown that this will change the acoustic environment and could compromise marine fauna, such as dolphin communication. This is the first study to document the whistle acoustic parameters from several dolphin species in the region before any disturbance. Opportunistic recordings were made in two different locations alongside the coast: Coquí, Chocó, and a few hundred kilometers north Bahía Solano, Chocó.
Figure 1. (a) The Colombian Pacific coast and (b) whale-watching locations and ports of the Pacific coast of Colombia. Ports are red markers and whale-watching spots are blue markers.
Five different delphinid species were recorded: Common bottlenose dolphin (Tursiops truncatus), Pantropical spotted dolphin (Stenella attenuata), Spinner dolphin (Stenella longirostris), False killer whale (Pseudorca crassidens) and Short- beaked common dolphin (Delphinus delphis). Comparing these recordings to those made from dolphin populations in more disturbed areas around the globe showed that the repertoires of four of the five species were different. These differences could be because the Chocó dolphins represent populations that use whistles with more natural features while the other, more disturbed, populations may have already changed their whistle features to avoid overlapping with boat traffic noise.
However, avoiding overlap with other conspecifics or other species in the same habitat is natural, too. This is called the acoustic niche hypothesis (ANH). The ANH states that geographically sympatric species should occupy specific frequency bands to avoid overlapping with each other. A Linear Discriminant Analysis (LDA) was done to explore whether the five different species have already adjusted their whistle features to avoid overlapping with other species. Frequency band separation is not the only feature of whistles that dolphins could adjust. The LDA used nine different features to observe if there is any natural division between any of the features.
Figure 2. LDA plot for nine whistle variables among the five species.
Tracking these whistle features in Chocó over time will help determine whether the different whistle features between the Chocó dolphins and dolphins from more disturbed areas are a result of the natural acoustic niche hypothesis or a result of noise pollution avoidance. If constructed, the port could force species to adjust their whistle features like populations from noisier habitats already have, and that could disrupt the acoustic niches that already exist, some of their whistles may still be interrupted by boat noise. Such disturbances could increase their stress levels or could lead to area abandonment, which would cause economic and ecological disasters for the region that relies on artisanal fishing and ecotourism.
The target for this work is on estimating the stiffness and other mechanical properties of the carotid artery, a well-known indicator of cardiovascular disease. To accomplish this aim, we use a technique called shear wave elastography, where the wave propagation characteristics measured in the arterial wall are used to estimate the stiffness of the artery. Specifically, we use acoustic radiation force, resulting from focused ultrasound waves from an ultrasound probe to tap on the wall of the artery. This tap creates waves that travel within the artery wall, which are also measured with the same ultrasound probe. In this work, we present algorithms that convert the wave motion measured with ultrasound to values of arterial stiffness.
Figure 2. LDA plot for nine whistle variables among the five species.