2pAO6 – Listening to Hydrothermal Vents

Brendan Smith – Brendan.Smith@dal.ca
Dr. David Barclay – David.Barclay@dal.ca
Dalhousie University
Department of Oceanography
Life Sciences Centre, 1355 Oxford St.
PO Box 15000
Halifax, NS
B3H 4R2, Canada

Popular version of 2pAO6 – Passive acoustic monitoring of hydrothermal vents at the endeavour hydrothermal vent field
Presented Tuesday morning, November 30, 2021
181st ASA Meeting
Click here to read the abstract

Long-term monitoring of hydrothermal vents is challenging due to their high temperature and caustic fluid properties. Passive acoustics provides a sustained vent monitoring method from a safe distance. Long-term acoustic records and hydrophone arrays may be used to investigate the sound producing mechanisms of hydrothermal vents. The initial results from an analysis of 6-months of single hydrophone acoustic data collected at the Main Endeavour Hydrothermal Vent field in the North-East Pacific, and a short-term array deployment at the same location demonstrate features of the vent’s signature.
The monitoring hydrophone, operated by Ocean Networks Canada (ONC) is within 10 meters of a black smoker hydrothermal vent. During a servicing cruise in the fall of 2021, ONC deployed the Deep Acoustic Lander (DAL), an autonomous acoustic recorder carrying a four-channel hydrophone array, shown in Fig. 1. The difference in received signals across the array can be exploited to identify hydrothermal vent generated noise and separate it from possible interferences, such as flow noise, wind generated wave noise, and ship noise.

 

The Deep Acoustic Lander being deployed by Ocean Networks Canada using an ROV near a black smoker hydrothermal vent [Credit: Ocean Networks Canada]”
Despite the vigorous, high-temperature flow seen from black smoker chimneys, they do not produce loud acoustic signals relative to the ocean’s background noise. However, several acoustic source mechanisms have been proposed to generate both tonal and broadband sounds (Lighthill, 1952; Little, 1988; Crone et al., 2006).

Fig. 2 compares audio spectra and vertical coherence from the DAL hydrophone array deployed at an initial standoff distance of 200 m, then subsequently repositioned to within 3 m from the vent outlet. Increased broadband infrasonic (1 – 10 Hz) and low frequency (100 – 200 Hz) energy is observed when the sensor is positioned near the vent, and tonal components at 4, 5, 7, 8, and 9 Hz are observed in the spectra. A reduction in coherence in the infrasonic band indicates flow noise while the coherent tonals may be generated by the vibrating vent structure.


Caption: “Figure 2: (a) Acoustic power spectra, (b) real and (c) imaginary vertical coherence <3m (solid) and >200m (dashed) from vent”
The outflow rate and temperature of hydrothermal vent fluid can modulate due to tidal variations in overburden pressure, causing a correlated variation in sound level (Barreyre & Sohn, 2016; Xu & Di Iorio, 2012; Larson et al., 2007; Crone & Wilcock, 2005; Crone et al., 2006). Tidal-period variations in sound level over 6 months of audio data were observed by carrying out a spectral analysis of power spectral density levels, shown in Fig. 3. Variations in sound level with the diurnal and semidiurnal tidal components are seen at infrasonic (1 – 10 Hz) and low (100 – 400 Hz) frequencies. The semidiurnal variability below 10 Hz is attributed to flow noise (Fig. 2) due to either tidal currents or vent plume entrainment. Variability between 100-400 Hz, above the flow noise regime, is generated by vent plume outflow and mixing.

 


Caption: “Figure 3: Periodic variability of power spectral density”
Combining the long-term records with data recorded on the Deep Acoustic Lander’s hydrophone array will allow the relationships between physical forcing and hydrothermal vent sound generation mechanisms and acoustic signatures to be further determined.

References
Barreyre, T., and Sohn, R. A. (2016). Poroelastic response of mid-ocean ridge hydrothermal systems to ocean tidal loading: Implications for shallow permeability structure. Geophys. Res. Lett., 43, 1660-1668, doi:10.1002/2015GL066479
Crone, T. J., and Wilcock, W. S. D. (2005). Modeling the effects of tidal loading on mid-ocean ridge hydrothermal systems. Geochem. Geophys. Geosyst., 6, Q07001, doi:10.1029/2004GC00905
Crone, T. J., Wilcock, W. S. D., Barclay, A. H., Parsons, J. D. (2006). The sound generated by mid-ocean ridge black smoker hydrothermal vents. PLoS ONE, 1(1): e133, doi:10.1371/journal.pone.0000133
Larson, B. I., Olson, E. J., Lilley, M.D. (2007). In situ measurement of dissolved chloride in high temperature hydrothermal fluids. Geochimica et Cosmochimica Acta, 71, 2510-2523, doi:10.1016/j.gca.2007.02.013
Lighthill, M. J. (1952). On sound generated aerodynamically I. General theory. Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences, 211(1107), 564-587, doi:10.1098/rspa.1952.0060
Little, S. A. (1988). Fluid flow and sound generation at hydrothermal vents. PhD thesis, Massachusetts Institute of Technology and Woods Hole Oceanographic Institution.
Xu, G., and Di Iorio, D. (2012). Deep sea hydrothermal plumes and their interaction with oscillatory flows. Geochem. Geophys. Geosyst., 13, Q0AJ01, doi:10.1029/2012GC004188

2pPPa1 – Flying bats modify their biosonar sounds to avoid interference from other bats

Andrea M. Simmons, andrea_simmons@brown.edu
Charlotte R. Thorson, charlotte_thorson@alumni.brown.edu
Madeline McLaughlin, madeline_mclaughlin1@brown.edu
Pedro Polanco, pedro_polanco@alumni.brown.edu
Amaro Tuninetti, amaro_tuninetti@brown.edu
James A. Simmons, james_simmons@brown.edu
Brown University
Providence RI 02912

Popular version of 2pPPa1 – Echolocating bats modify biosonar emissions when avoiding obstacles during difficult navigation tasks
Presented Tuesday afternoon, December 2, 2021
181th ASA Meeting, Seattle WA
Click here to read the abstract

Bats use echolocation, an active biological sonar, to find their way in the dark. By broadcasting trains of intense ultrasonic sounds and listening to returning echoes, they can locate and identify obstacles to their flight (vegetation, buildings) and capture small insect prey. Bats often fly and forage in groups. When other flying bats are present, they face the added challenge of separating out the echoes from their own broadcasts from the broadcasts and echoes created by these other bats, while still maintaining their flight path. To assess how bats address these challenges, we flew individual and then pairs of big brown bats (Eptesicus fuscus) through a curved flight corridor bounded by rows of closely spaced vertical hanging plastic chains that produced echoes mimicking those produced by dense vegetation. When flying alone, each bat broadcasts sonar sounds containing frequencies from 100-25 kHz in a characteristic pattern of alternating long and short time intervals. These short time intervals allow fast reactions to immediate collision hazards, while the long intervals allow the bat to peer deep into its surroundings to plan its upcoming flight path. When two bats fly towards each other from opposite ends of the curved corridor, they maneuver to avoid colliding. There are three distinctive biosonar reactions tied to these maneuvers. First, both bats increase the strength of their broadcasts (Lombard effect) during the brief time they are in close proximity. Second, they produce more short time intervals, speeding up their broadcast rate. Third, at the point where they are in closest proximity and the need for each bat to avoid being interfered with by the other bat is most acute, one of them sharply decreases the low-frequency end of its broadcasts to about 15 kHz. This unusual, asymmetric response allows this bat to distinguish echoes of its own broadcasts from those of the other bat, even though the total range of frequencies remains large. Bats place particular priority on the lowest frequencies in echoes, and having different lowest frequencies lets them separate out each other’s biosonar broadcasts and prevent mutual interference when close together.

1pNS1 – Innovative Solutions for Acoustic Disturbances Occurring in Slender Buildings

Bonnie Schnitta – bonnie@soundsense.com
Sean Harkin – sean@soundsense.com
Patrick Murray – patrick@soundsense.com
Collin Champagne – collin@soundsense.com
jeremy Newman – jeremy@soundsense.com

SoundSense, LLC
39 Industrial Rd, Unit 6
PO Box 1360
Wainscott, NY 11975

Popular version of paper ‘1pNS1 – Innovative solutions for acoustic disturbances occurring in slender buildings
Presented Monday Afternoon, 1:20PM, November 29, 2021
181st ASA Meeting, Seattle, Washington
Click to read the abstract

The construction of tall, slender buildings is trending globally. Structural engineering has made it possible for architects to achieve soaring heights with a smaller building footprint, leaving yesterday’s skyscrapers a thing of the past. The typical height to base ratio of a slender building is 10:1, although an 18:1 ratio is more common today. Tall buildings must flex and bend to absorb wind loads. As the ratio of height is increased, the impact caused by the wind on the slabs of each floor is also increased. This impact causes added movement of the walls, floors and ceilings which generate audible sounds of snap, creak, and pop. Regular exposure to this phenomenon may negatively impact the health and quality of life for the occupants. These disturbances can cause someone of normal hearing to wake from sleep or have their concentration disrupted, which is a growing concern for those individuals working from home. Medical experts have stated that exposure to this type of noise at home may cause stress, depression, high blood pressure, tension, tiredness, fatigue, or sleeplessness.
The presentation by SoundSense’s Founder and CEO, Dr. Bonnie Schnitta, at the upcoming Acoustic Society of America conference will show how to measure the sound and vibration in slender buildings during high wind conditions and what solutions exist for the findings. Case studies will be used to show how novel techniques have been used by SoundSense successfully in various projects.

In addition to showing how to engineer rooms that will acoustically withstand high wind conditions without excessive building sounds, interior architecture will be discussed to highlight how some designs may actually contribute to secondary noises. The presentation will cover the following:
• Use of insulation, density and resiliency to upgrade the acoustic properties of walls, preventing room to room noise transmission;
• Attachment of pipes and ductwork to walls or slabs using flexible connections, springs or rubber pads;
• How to appropriately use resilient seals in windows.

A device recently patented will be introduced to show how to assess acoustic leakage points, as even the smallest gap in the construction of a wall may compromise the efficacy of an acoustic treatment.

The importance of including materials that function as acoustic absorbers in any project’s design will also be discussed. Slender buildings typically utilize hard, reflective materials in large rooms, such as glass or drywall. When sound waves bounce off such surfaces it will create an echoey space that often amplifies noise.
The solutions developed by SoundSense to be presented at the upcoming ASA conference, will inform the attendees on the benefits of thoughtful, acoustic design to ensure the reduction or elimination of interior noise in Slender Buildings.

 

Bonnie Schnitta of Soundsense

5aABb2 – A tale of two singers: how do bats and bird mixed-flocks respond to petroleum industry noise in the Ecuadorian Amazon

Rivera-Parra, JL, jose.riverap@epn.edu.ec
De la Cruz, I.
Viscarra, S.
Vasconez, C.
Dueñas, A.
Xulvi, R.
Sorriso-Valvo, L.

Popular version of 5aABb2 – A tale of two singers: how do bats and bird mixed-flocks respond to petroleum industry noise in the Ecuadorian Amazon
Presented Friday morning, December 3, 2021
181st ASA Meeting, Seattle, WA
Click here to read the abstract

Industrial noise can have a significant impact on animal groups that rely on acoustic communication for fundamental survival activities. Our research focuses on two of these groups: insectivorous bats, which use ultrasound to navigate and find food; and mixed flocks of insectivorous birds, that rely on vocalizations to communicate about foraging direction and potential threats. The Yasuni Bio-sphere Reserve in the Ecuadorian Amazon is one of the most biodiverse spots in the world, but it is also a place with thriving oil exploitation activities.

It is well known that some disturbance, such as roads, or industrial noise, can be related to biodiversity loss, however, how much of these effects can be attributable to the noise caused by the oil exploitation have never been measured, nor has it been characterized. Furthermore, characterization of noise is usually done only in the audible spectrum, meaning the frequencies that us as hu-mans can hear, but is not done taking into account ultrasound.

To characterize the noise caused by oil exploitation we selected three different places, based on the potential source related to the oil industry, plus a control point: 1) drilling site, 2) processing facilities, 3) a control site, a forest with no disturbance. For all three sites recordings of both audible and ultrasonic sound were made in a transect from the border of the source of industrial noise to-wards the forest. To further analyze the effects of the noise, biological surveys were made both in birds and bats. We characterized bats and birds vocalizations, and the industrial noise profile, both in ultrasound and audible frequencies.

Our results suggest, in both groups, the immediate response is avoidance; this results, in the short and long term, in a biodiversity loss. These effects are proportional to how much noise the habitat itself absorbs, the complexity of the habitat, the complexity of the noise, and the distance from the source. In the long term the effects seem to include a change on habitat use, and modification on community composition. Thus is possible it can cause a disruption of ecosystem services by bats and birds, such as natural pest control, polinization, and seed dispersal, which can lead to a broader change in forest dynamic.

petroleum industry noise

3pPA4 – Military personnel may be exposed to high level infrasound during training

Alessio Medda, PhD – Alessio.Medda@gtri.gatech.edu
Robert Funk, PhD – Rob.Funk@gtri.gatech.edu
Krish Ahuja, PhD – Krish.Ahuja@gtri.gatech.edu
Aerospace, Transportation & Advanced Systems Laboratory
Georgia Tech Research Institute
Georgia Institute of Technology
260 14th Street NW
Atlanta, GA 30332

Walter Carr, PhD – walter.s.carr.civ@mail.mil
Bradley Garfield – bradley.a.garfield.ctr@mail.mil
Walter Reed Army Institute of Research (WRAIR)
503 Robert Grant Avenue
Silver Springs MD 20910

Popular version of 3pPA4 – Infrasound Signature Measurements for U.S. Army Infantry Weapons During Training
Presented Wednesday morning, December 1, 2021
181st ASA Meeting, Seattle, WA
Click here to read the abstract

Infrasound is defined as an acoustic oscillation with frequencies below the typical lower threshold of human hearing, typically 20 Hz. Although infrasound is considered too low in frequency for humans to hear, it was shown that infrasound could be heard down to about 1 Hz. In this low-frequency range, single frequencies are not perceived as pure tones but are experienced as shocks or pressure waves, through the harmonics generated by the distortion from the middle and inner ear. Moreover, it has been shown that infrasound exposure also can have an effect on the human body, when sound of sufficient intensity is absorbed and stimulates biological tissue to produce effects similar to whole-body vibrations.

United States military personnel are exposed to blast overpressure from a variety of sources during training and military operations. While it is known that repeated exposure to high-level blast overpressure may result in concussion like symptoms, the effect of repeated exposure to low-level blast overpressure is not well understood yet. Exposure to low-level blast rarely produces a concussion, but anecdotal evidence from soldiers indicates that it can still produce transient neurological effects. During interviews, military personnel described the effect of firing portable antitank weapons like “getting punched in your whole body.” In addition, military personnel involved with breaching operations often use the term “breacher’s brain” to identify symptoms that include headache, fatigue, dizziness, and memory issues.
Impulsive acoustic sources such as pressure waves generated by explosions, artillery launches, and rocket launches are typically characterized by a broadband acoustic energy with frequency components well into the infrasound range. In this study, we explore how routine infantry training can result in high level repeated infrasound exposures by analyzing acoustic recordings and highlighting the presence of infrasound.

We present results in the form of time-frequency plots, which have been generated using a technique based on wavelets, a mathematical approach that represents a signal at different scales and uses unique features at each scale. This technique is called Synchrosqueezed Wavelet Transform and it was proposed by Daubechies et al. in 2011. In Figure 1 we show examples of high energy infrasound for three weapons commonly used during infantry training in the US military. Figure 1(A) shows the time-frequency plot of a grenade explosion, Figure 1(B) shows the time-frequency plot obtained from recordings of machine gun fire, and Figure 1(C) shows the time-frequency plot obtained from a recording of a rocket launched from a shoulder-held weapon.

Results indicate that high infrasound levels are present during military training events where impulsive noise is present. Also, service members that are routinely part of these training exercises have reported concussion-like symptoms associated with training exposures.

Through this research, we have an opportunity to establish the nature of the potential threat from infrasound in training environments as a preparation for future studies aimed at developing dose-response relationships between neurophysiological outcomes and environmental measurements.

Time-frequency spectrum for recordings of (A) Grenade Blast, (B) Machine Gun fire, and (C) Rocket Launcher from shoulder weapon. Regions characterized by high energy appear hotter (red) while normal conditions are cooler (blue).