Low Frequency Content Research Articles

Linking the scaling of tremor and slow slip near Parkfield, CA

There has been much debate about the fault zone processes that generate slow earthquakes, including tremor and slow slip. Indeed, we still debate whether tremor and slow slip are generated by the same process operating at different scales or by two distinct processes. Here we investigate tremor scaling near Parkfield, California; we examine how rupture duration scales with moment. We thoroughly search for and detect the low frequency earthquakes (LFEs) that constitute tremor and robustly estimate their durations. Our results show varying durations (0.1–0.6 s) and spectra for LFEs at the same location. These variations confirm a common assumption, that LFEs’ observed low frequency contents are due to source processes, not path effects. The LFEs’ amplitude and spectra variations are consistent with a linear moment-duration scaling: the same scaling observed among slow slip events. The similar scaling suggests that tremor and slow slip events are governed by the same fault zone process and that when we attempt to identify the process creating slow earthquakes, we should focus on processes which allow higher slip rates on smaller faults.

Advocating the use of C weighted measurements in sound ordinances to manage modern music entertainment sound

Indoor and outdoor modern music entertainment since the 1980s has had incrementally more low frequency content with the advent of inexpensive, efficient, and portable subwoofers. Commercial sound reinforcement systems are being developed to reproduce lower frequencies and higher sound levels. Once sound leaves the venue, the low frequencies can travel the furthest, diffract around obstacles, and more easily penetrate building envelopes; in addition, it often comes in the form of impulses which are more easily detectable by the listener. Many ordinances only utilize A weighted sound metrics, which leaves enforcement at a loss to remedy low frequency complaints using sound level violations. This paper will examine the sound spectra of different musical genres, modern sound systems, building envelope sound transmission, frequency based propagation, and sound measurement metrics, and the resulting need for and advantages of the use of C weighted measurements. The material is intended to provide a comprehensive way to explain the benefits of C weighted limits and measurements to stakeholders in ordinance development and enforcement.

Duration Effects of Near-Fault Ground Motions on Structural Seismic Responses

ABSTRACT This study reveals the duration effects of near-fault ground motions with distinct long-period pulse and without pulse on structural seismic responses and damage. To this end, several velocity-based duration measures (DMs) are proposed according to the characteristic of abundant low-frequency content in near-fault records, and non-structural compound intensity measures (IMs) incorporating DMs are suggested. Moreover, the correlations between the IMs and DMs of near-fault ground motions, as well as those between the IMs and DMs of ground motions and the seismic responses (i.e. maximum displacement D max, input energy E I and hysteretic energy E H) of bilinear single-degree-of-freedom (SDOF) systems, are scrutinized. It is shown that the acceleration-based absolute uniform durations present strong correlation with the acceleration-related IMs, while the velocity-based absolute uniform durations highly correlate with the velocity- and displacement-related IMs. In the short-period region, the acceleration-based absolute uniform duration U 0.10 g is well correlated with the seismic responses, while in the medium-, medium-long- and long-period regions, the velocity-based absolute uniform duration U v10 exhibits strong correlation. Additionally, the compound IMs combining with uniform durations (PGA•U 0.10 g and PGV•U v10) are the competent indices to quantify duration effects of near-fault records. The similar observations for duration effects are validated by four representative frame buildings considering Bouc-Wen hysteretic behavior without or with degradation of strength and stiffness.

EA-Net: Edge-aware network for brain structure segmentation via decoupled high and low frequency features

Automatic brain structure segmentation in Magnetic Resonance Image (MRI) plays an important role in the diagnosis of various neuropsychiatric diseases. However, most existing methods yield unsatisfactory results due to blurred boundaries and complex structures. Improving the segmentation ability requires the model to be explicit about the spatial localization and shape appearance of targets, which correspond to the low-frequency content features and the high-frequency edge features, respectively. Therefore, in this paper, to extract rich edge and content feature representations, we focus on the composition of the feature and utilize a frequency decoupling (FD) block to separate the low-frequency and high-frequency parts of the feature. Further, a novel edge-aware network (EA-Net) is proposed for jointly learning to segment brain structures and detect object edges. First, an encoder–decoder sub-network is utilized to obtain multi-level information from the input MRI, which is then sent to the FD block to complete the frequency separation. Further, we use different mechanisms to optimize both the low-frequency and high-frequency features. Finally, these two parts are fused to generate the final prediction. In particular, we extract the content mask and the edge mask from the optimization feature with different supervisions, which forces the network to learn the boundary features of the object. Extensive experiments are performed on two public brain MRI T1 scan datasets (the IBSR dataset and the MALC dataset) to evaluate the effectiveness of the proposed algorithm. The experiments show that the EA-Net achieves the best performance compared with the state-of-the-art methods, and improves the segmentation DSC score by 1.31% at most compared with the U-Net model and its variants. Moreover, we evaluate the EA-Net under different noise disturbances, and the results demonstrate the robustness and superiority of our method under low-quality noisy MRI. Code is available at https://github.com/huqian999/EA-Net.

Effect of Choke Placement on Common-Mode Noise in Three-Phase Variable Speed Drives

Three-phase variable speed drives play a key role in energy conversion systems. To comply with the electromagnetic compatibility standards for the 0–2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{kHz}$</tex-math></inline-formula> frequency range, magnetic chokes are typically placed at the dc or ac sides of the drive systems. Recently, compatibility levels have been defined at 9–150 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{kHz}$</tex-math></inline-formula> for the public network in accordance with IEC 61000-2-2. At this frequency range, common-mode noise is an important factor affecting electromagnetic compatibility. This article analyzes the effect of choke placement on common-mode noise at the 9–150 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{kHz}$</tex-math></inline-formula> frequency range. In particular, a comparative study on choosing either two dc-link choke inductors or three ac-line inductors is carried out via mathematical calculations. To this end, single-phase common-mode equivalent models are extracted for each placement of dc and ac chokes. Subsequently, by calculating the transfer functions of the currents in the single-phase equivalent circuits, the attenuation rate of common-mode currents from the motor to the grid side is analytically modeled for each choke configuration. The developed theories prove that ac-line inductors are more effective at suppressing low-frequency common-mode contents, while dc chokes are useful in attenuating high-order noise contents. Laboratory test results are used to prove the validity of the presented theoretical modeling and analysis.

Simulation of near-field pulse-like ground motions using a correlated bimodal fractional stochastic model

This paper introduces a two-part stochastic method to simulate completely nonstationary pulse-like records and capture several peaks in the power spectrum. Based on the evolutionary power spectral density compatibility of the acceleration ground motion in different stages, the model is fitted to the target records. The proposed model is flexible enough to consider the decay rate variability of the high-and low-frequency content of the ground motions. Also, using the circular shift and IFFT techniques, the discretization of the model is performed such that the simulation cost is significantly reduced. The horizontal components of 178 near-filed pulse-like ground motions with a rupture distance of less than 10 km, with strike-slip and dip-slip mechanisms, are simulated using the proposed method. The model's efficiency is investigated using different criteria such as the elastic response spectra, Arias intensity, zero-crossing, Fourier spectrum, and the 2DOF system response. Moreover, the simulated records' pulse-like characteristics are investigated, and the model's capability to generate an ensemble of desirable ground motions is studied. Comparing the results with the previous models reveals that the model can generate more compatible records with the seed ones according to various aspects.

Three-dimensional effects associated with the low-frequency breathing motion of a turbulent separation bubble

In this article, we address the low-frequency dynamics of a turbulent separation bubble (TSB) with a mean length of Lb ≈ 0.18 m that occurs in a one-sided diffuser at an inflow velocity of U∞ = 20 m/s. Distinct low-frequency content at Strouhal numbers of O(f Lb/U∞) = 0.01 is detected through time-resolved wall pressure measurements. By applying Spectral Proper Orthogonal Decomposition to velocity fluctuations in the diffuser symmetry plane, these pressure fluctuations can be linked to a large-scale longitudinal contraction/expansion motion falling into the same frequency range. Further velocity field measurements in cross-sections of one diffuser half-plane indicate that the mean flow field of the TSB is characterized by a near-surface outward-directed velocity component and a large-scale streamwise side wall vortex. During the expanded TSB state, however, these flow features are suppressed as the streamwise velocity is temporarily increased near the side wall but reduced near the symmetry plane. The results presented in this article suggest that the low-frequency breathing motion is a highly three-dimensional phenomenon. Future studies should address the associated complex dynamics that are shown to be governed by aperiodic events of temporary TSB expansion.

Development of metric models to predict annoyance due to tonal office noise

To guide the design of a comfortable office environment, a proper understanding of people’s annoyance due to exposure to tonal office noise is valuable. The purpose of the research described in this paper is to develop models to relate sound metric values to people’s perceived annoyance level due to tonal office noise exposure. Thirty subjects with normal hearing participated in a multiple-part test in an office-like environment. Subjects were asked to rate sounds with different tone levels and tone frequencies, with and without a harmonic. The ambient broadband noise level was also varied. Two annoyance prediction models were developed to predict the average of the responses to each of the 222 sounds used in the test. Both models are functions of sound metrics related to level, tonalness, spectral balance, and low-frequency content. One model is potentially more useful when quantifying, for a particular environment, the increase in annoyance due to the presence of tones. The other model is more appropriate for comparing different office environments with varying levels of both broadband noise and tones. The performance of both models is examined by comparing their predictions with subjects’ averaged annoyance ratings from another test.

Auralizing comparable structural vibration measurements to inform design decisions

The design challenges presented by locating high-impact noise-producing athletic spaces, such as weight rooms and gymnasia adjacent to other occupied spaces are compounded by the difficulty in conveying the resulting experience through narratives or numeric performance criteria. As auralization tools can very effectively convey experiences in room acoustics and sound isolation, that effectiveness prompted an exploration into its possible use for conveying the experiences of impact-induced noise transfer resulting from difficult adjacencies. However, realistic and accurate auralization of a structural vibration path offers far more complex challenges than typical auralizations. For example, structural modeling for building design typically does not reach the resolution required for auralizations, if performed at all. Performance data for comparative floor types typically use tapping machines to comply with the Impact Isolation Class (IIC), which does not represent the response low-frequency content induced by heavy impacts. This paper dissects a case study of a method developed to address these challenges presenting a comparative auralization between athletic and gymnasium floor underlayment systems, enabling a client to experience the relative differences to aid design decisions. This included a method of presenting structural vibration with realistic source noise components and room effects to achieve a full soundscape.

The study of soft soil seismic subsidence based on the 3D OpenSees model

AbstractSoft soils are characterized by high sensitivity, low strength, and susceptibility to seismic subsidence. In this study, nonlinear dynamic finite element analysis was performed using the OpenSees numerical simulation method to evaluate the seismic subsidence response of soft soil sites to ground motions. Higher peak acceleration of ground motion was found to enhance the degree of uneven seismic subsidence, depth of the seismic depression, and damage to the horizontal surface. The frequency characteristic of ground motion is another factor that influences the seismic subsidence of soft soil. Ground motions with low-frequency contents or high amplitudes lead to a more pronounced seismic subsidence of soft soil, particularly in the case of ground motion that exhibits frequency predominantly close to one of the soil sites. The findings of this study expand the current understanding of seismic subsidence of soft soil.

POD analysis of the wake dynamics of an offshore floating wind turbine model

The wake dynamics of a floating wind turbine model experiencing realistic surge motion and immersed within a properly scaled atmospheric boundary layer is studied through wind tunnel experiments. The turbine is modelled by a porous disk representing the floating 2MW wind turbine located at the offshore test site in Le Croisic (France). Experiments were conducted in the LHEEA’s atmospheric wind tunnel. A surge motion is imposed on the model, using a linear actuator, to replicate realistic behaviors under wave swell. Realistic frequencies of actuation are considered to study their effects on the wake properties. The wake is characterized using Stereoscopic Particle Image Velocimetry (SPIV) measurements in a y - z plane normal to the flow, at two different streamwise locations x = 4.6D and 8.1D. In addition to the documentation of the main wake statistics, the velocity fields are analyzed using Proper Orthogonal Decomposition (POD). The velocity field is decomposed into a set of spatial and temporal modes. The eigenvalues convergence is shown to be relatively slow, due to the high Reynolds number turbulent boundary layer within which the model is immersed. When varying the surge motion frequency, the spatial modes do not show any significant change in shape and amplitude. However, the spectral analysis performed on the temporal modes shows the emergence of peaks at the surge motion frequency and the overall increase of the low-frequency energy content in the Power Spectral Density, in particular for the highest frequencies of motion tested.

Unsteady Aspects of Shock-Wave/Boundary-Layer Interaction Resulting from Control Surface Deflection

A computational investigation of a Mach 6.9 turbulent flow near the juncture (cove) of a wing’s trailing-edge and elevon was carried out. Turbulence was modeled using improved delayed detached eddy simulation (IDDES). The computational data were compared to the results of an experimental study, conducted by Deveikis and Bartlett, which simulated the flow over the windward surface of the NASA space shuttle. Flow visualization, surface variable comparison with experiment, and analysis of unsteady flow statistics were carried out. Reasonable agreement between prediction and measurement was obtained for time-averaged surface pressure and heat flux. Unsteady analysis of these quantities revealed spectra dominated by low-frequency energy content throughout the interaction region. A correlation analysis indicated coupling of the unsteady motions of the shear layer, shock wave, separation vortex, and flow reattachment. The results of the present study suggest that IDDES can be a valuable tool for the analysis of heating and unsteadiness in hypersonic gap flows.

Prediction of the tidal turbine power fluctuations from the knowledge of incoming flow structures

After positioning a 1:20 scaled model of a three-bladed horizontal-axis turbine in the wake of a wall-mounted cylinder, synchronized turbine performance and flow measurements are carried out to investigate the relationship between the incoming flow field and the turbine power fluctuations. The Linear Stochastic Estimation (LSE) is used to predict the turbine output fluctuations from the knowledge of the Large Scale flow Structures (LSS) embedded in the incoming turbulent flow. LSS extraction by Fourier analysis or Proper Orthogonal Decomposition shows that LSS are responsible for the main unsteady variations of the power fluctuations, especially their highest amplitudes. The RMS of turbine output fluctuations are entirely due to the LSS. It is also demonstrated that whatever the nature of the incoming turbulent flow is, the low frequency filtering process coupled with the LSE method allows the recovering of at least 90% of the turbine power RMS. Furthermore, the low-frequency spectral content of the turbine power fluctuations is very well predicted, especially the frequency peaks. A preliminary LSE application is performed in order to predict the instantaneous turbine output fluctuations at more than 85% confidence level, from only three velocity signals measured in front of the turbine.

Unravelling a 2300 year long sedimentary record of megathrust and intraslab earthquakes in proglacial Skilak Lake, south‐central Alaska

AbstractSeismic hazards in subduction settings typically arise from megathrust, intraslab and crustal earthquake sources. Despite the frequent occurrence of intraslab earthquakes in subduction zones and their potential threat to communities, their long‐term recurrence behaviour is barely studied. Sedimentary sequences in lakes may register ground shaking from different seismic sources. This study investigates two long sediment cores (13 m and 16 m) from Skilak Lake, a proglacial lake in south‐central Alaska, to evaluate whether different seismic sources leave a distinct imprint. The sedimentary record shows a continuously varved sediment sequence, occasionally interrupted by turbidites, slump deposits and tephra beds. Turbidites and slump deposits were objectively identified using a statistical outlier analysis on varve thickness. The earthquake origin of these deposits was ascertained by resemblance with deposits induced by instrumentally recorded earthquakes (for example, 1964 ce Mw 9.2 megathrust and 1954 ce Mw 6.4 intraslab earthquakes) and correlation with multiple coeval landslide deposits on sub‐bottom profiles. The Skilak Lake record chronicles 19 earthquakes with moderate to very high confidence level in the past 1350 years. The sedimentary evidence of instrumentally‐recorded intraslab and megathrust earthquakes within the past 70 years demonstrates that not only megathrust earthquakes, but also past intraslab events are recorded. Although reported seismic intensities at Skilak Lake are comparable for the 1964 ce megathrust and the 1954 ce intraslab earthquakes, the long duration and low frequency content of seismic ground motion during megathrust earthquakes facilitate the triggering of multiple, voluminous landslides and the generation of megaturbidites. In contrast, the shorter duration and higher frequency source spectrum of intraslab earthquakes may only induce surficial slope remobilization and the generation of thinner turbidites. This study demonstrates that the sedimentary record of Skilak Lake has the potential to decipher multiple seismic sources, which opens possibilities for a comprehensive seismic hazard analysis for south‐central Alaska.

Managing occupational noise from blasts

The aim of this work is to examine the current best practice for the assessment of auditory hazards associated with occupational impulsive noise for a UK-based test site. A summary of the literature is presented on the measurement methodologies, hearing conservation, and relevant guidance for the selection of hearing protection within the context of near-field impulsive noise. The current U,K. best practice recommends the adapted HML method from Defence Standard 0027:2015 using a C-peak measurement of exposure to compare with the national regulations. On-site measurements were made at the DNV Spadeadam Testing and Research Site (STaR), which performs full-scale high-intensity blast testing. Analyses of the trials data show that the C-peak personnel exposures resulted in acceptable levels below the 140dBCpk limit within the national regulations when using the prescribed hearing protection, according to the adapted HML method. It is concluded that the adapted HML assessment is unclear on how excessive low-frequency content and multiple pressure peaks are accounted for. The implication of this work is that further research is required to improve current best practice to quantify the uncertainties introduced by the additional characteristics found within real impulsive noise exposures.

Effect of clocking on entropy noise generation within an aeronautical high pressure turbine stage

This article reports a detailed experimental and numerical study of the clocking effect between entropy wave spots and stator leading edges on the evolution of the entropy wave and on indirect noise generation in a high pressure turbine stage. Experimental campaigns considering burner-representative temperature fluctuations injected upstream of an uncooled high-pressure gas turbine stage have been performed in the high-speed closed-loop test rig of the Fluid Machine Laboratory (LFM) of the Politecnico di Milano. Acoustic measurements focused on entropy noise generation have been carried out by the German Aerospace Center, DLR with two flush mounted in-duct microphone arrays. URANS CFD simulations with and without entropy fluctuations imposed at the stage inlet were performed with the TRAF code, developed by the Università degli Studi di Firenze. A numerical post-processing procedure, based on the time and space discrete Fourier transform (DFT) of the conservative variables, has been implemented to extract the low-frequency content connected to the entropy fluctuations and indirect noise emissions. Simulations show an overall good agreement with the experiments, especially at the stage outlet thus confirming the possibility to predict entropy noise by means of URANS simulations with time varying inlet conditions. By exploiting the combination of experiments and simulations, the evolution of the entropy wave, the identification of entropy noise generation areas, and the evaluation of indirect noise emissions, for the different clocking positions were properly assessed. This study also demonstrates that this type of simulations can be used for the geometric design optimization of combustor/turbine coupling performing detailed parametric studies concerning the clocking position of the perturbation source in order to reduce the turbine-combustor interactions and the indirect noise emissions.

Spatial frequency bands used by patients with glaucoma to recognize facial expressions

ABSTRACT The authors investigated the influence of spatial frequencies in foveal vision in glaucomatous patients in a recognition task of facial expressions. Nineteen patients, 16 age-matched and 14 young controls saw centrally presented photographs of faces. Participants categorized the facial expressions as happy, angry or neutral. Two versions were tested: filtered faces of either low (LSF) or high (HSF) spatial frequency content and hybrid faces constructed from a face with LSF content superimposed on a face with HSF content with differing facial expressions. Compared to age-matched controls a significant deficit was observed both on HSF and on LSF filtered faces for patients. Controls, but not patients, were biased towards the HSF component of the hybrid faces. Different spatial frequencies are normally used to recognize different facial expressions. Impaired processing of a spatial frequency bandwidth due to an ocular pathology can therefore lead to misinterpretation of emotions, and impact on social interactions.

Pneumatic system for pressure probe measurements in transient flows of non-ideal vapors subject to line condensation

This paper presents the design, construction and commissioning of a pneumatic system for pressure probe measurements in flows of organic vapors in non-ideal conditions, namely in the thermodynamic region close to the liquid–vapor saturation curve and the critical point where the ideal gas law is not applicable.Experiments were carried out with fluid siloxane MM (hexamethyldisiloxane, C6H18OSi2), commonly employed in medium/high temperature Organic Rankine Cycles (ORCs), in the Test Rig for Organic VApors (TROVA), a blow-down wind tunnel at the Laboratory of Compressible fluid dynamics for Renewable Energy Applications (CREA lab) of Politecnico di Milano. TROVA operation is intrinsically transient due to its batch nature, with a low frequency content (∼1Hz) related to the emptying of the high-pressure reservoir feeding the test section.The challenges linked to possible condensation in pneumatic lines, such as vapor–liquid menisci, hydrostatic head and mass-sink effects, were evaluated by means of theoretical calculation and experiments. To avoid these issues, a nitrogen-flushed pneumatic system for absolute and differential pressure measurements was designed and successfully tested with superheated MM vapor expanding in planar choked converging nozzles characterized by a portion with constant cross-sectional area yielding design Mach numbers of 0.2, 0.5 and 0.7. Commissioning of the complete system including a probe was performed with the first ever testing of an L-shaped Pitot tube in non-ideal subsonic flows of siloxane MM vapor at Mach numbers M=0.2 and 0.5. Measurement delay issues were identified and assessed through a dynamic testing procedure, and were solved by reducing the overall pneumatic lines volume including the one hidden within pressure transducers. The correct performance of the complete system was therefore verified for probe measurements of total, static and dynamic pressure in non-ideal flows of organic vapors. This sets the foundation for future directional pressure probes calibration and use in the characterization of such flows, as in direct measurement of total pressure losses across shocks and in testing of ORC turbine blade cascades.

The Spectral Extent of Phasic Suppression of Loudness and Distortion-Product Otoacoustic Emissions by Infrasound and Low-Frequency Tones

We investigated the effect of a biasing tone close to 5, 15, or 30 Hz on the response to higher-frequency probe tones, behaviorally, and by measuring distortion-product otoacoustic emissions (DPOAEs). The amplitude of the biasing tone was adjusted for criterion suppression of cubic DPOAE elicited by probe tones presented between 0.7 and 8 kHz, or criterion loudness suppression of a train of tone-pip probes in the range 0.125–8 kHz. For DPOAEs, the biasing-tone level for criterion suppression increased with probe-tone frequency by 8–9 dB/octave, consistent with an apex-to-base gradient of biasing-tone-induced basilar membrane displacement, as we verified by computational simulation. In contrast, the biasing-tone level for criterion loudness suppression increased with probe frequency by only 1–3 dB/octave, reminiscent of previously published data on low-side suppression of auditory nerve responses to characteristic frequency tones. These slopes were independent of biasing-tone frequency, but the biasing-tone sensation level required for criterion suppression was ~ 10 dB lower for the two infrasound biasing tones than for the 30-Hz biasing tone. On average, biasing-tone sensation levels as low as 5 dB were sufficient to modulate the perception of higher frequency sounds. Our results are relevant for recent debates on perceptual effects of environmental noise with very low-frequency content and might offer insight into the mechanism underlying low-side suppression.

Potential impacts from simulated vessel noise and sonar on commercially important invertebrates.

Human usage of coastal water bodies continues to increase and many invertebrates face a broad suite of anthropogenic stressors (e.g., warming, pollution, acidification, fishing pressure). Underwater sound is a stressor that continues to increase in coastal areas, but the potential impact on invertebrates is not well understood. In addition to masking natural sound cues which may be important for behavioral interactions, there is a small but increasing body of scientific literature indicating sublethal physiological stress may occur in invertebrates exposed to high levels of underwater sound, particularly low frequency sounds such as vessel traffic, construction noise, and some types of sonar. Juvenile and sub-adult blue crabs (Callinectes sapidus) and American lobsters (Homarus americanus) were exposed to simulated low-frequency vessel noise (a signal was low-pass filtered below 1 kHz to ensure low-frequency content only) and mid-frequency sonar (a 1-s 1.67 kHz continuous wave pulse followed by a 2.5 to 4.0 kHz 1-s linear frequency modulated chirp) and behavioral response (the animal’s activity level) was quantified during and after exposure using EthoVision XT™ from overhead video recordings. Source noise was quantified by particle acceleration and pressure. Physiological response to the insults (stress and recovery) were also quantified by measuring changes in hemolymph heat shock protein (HSP27) and glucose over 7 days post-exposure. In general, physiological indicators returned to baseline levels within approximately 48 h, and no observable difference in mortality between treatment and control animals was detected. However, there was a consistent amplified hemolymph glucose signal present 7 days after exposure for those animals exposed to mid-frequency sound and there were changes to C. sapidus competitive behavior within 24 h of exposure to sound. These results stress the importance of considering the impacts of underwater sound among the suite of stressors facing marine and estuarine invertebrates, and in the discussion of management actions such as protected areas, impact assessments, and marine spatial planning efforts.