scholarly journals Ship noise in an urban estuary extends to frequencies used for echolocation by endangered killer whales

2015 ◽  
Author(s):  
Scott Veirs ◽  
Val Veirs ◽  
Jason D Wood
Keyword(s):  
Transmission Loss ◽  
Source Spectrum ◽  
Automatic Identification ◽  
Identification System ◽  
Underwater Sound ◽  
Killer Whales ◽  
Noise Sources ◽  
Low Frequencies ◽  
High Frequencies ◽  
Location Data

Combining calibrated hydrophone measurements with vessel location data from the Automatic Identification System, we estimate underwater sound pressure levels for 1,582 unique ships that transited the core critical habitat of the endangered Southern Resident killer whales during 28 months between March, 2011, and October, 2013. Median received spectrum levels of noise from 2,812 isolated transits are elevated relative to median background levels not only at low frequencies (20-30 dB re 1 microPa2/Hz from 100-1000 Hz), but also at high frequencies (5-13 dB re 1 microPa2/Hz from 10,000-96,000 Hz). Thus, noise received from ships at ranges less than 3 km extends to frequencies used by odontocetes like the Southern Resident orcas for communication and echolocation. Broadband received levels (20-96,000 Hz) near the shoreline in Haro Strait (WA, USA) for the entire ship population were 111 +/- 6 dB re 1 microPa on average. Mean ship speed was 14.4 +/- 4.1 knots. Most ship classes show a linear relationship between received level and speed with a slope near +1 dB/knot. Assuming near-spherical spreading based on a transmission loss experiment, we compute mean broadband source levels for the ship population of 173 +/- 7 dB re 1 microPa @ 1 m without accounting for frequency-dependent absorption, and 178 +/- 13 dB re 1 microPa @ 1 m with absorption. Spectrum, 1/12-octave, and 1/3-octave source levels for the whole population have median values that are comparable to previous measurements and models at most frequencies, but for select studies may be relatively low below 200 Hz and high above 20,000 Hz. Median source spectrum levels (without accounting for absorption) peak near 50 Hz for all 12 ship classes, have a maximum of 159 dB re 1 microPa2/Hz @ 1 m for container ships, and vary between classes by about 25 dB re 1 microPa2/Hz @ 1 m at low frequencies (50 Hz), 13 dB re 1 microPa2/Hz @ 1 m at mid-frequencies (1,000 Hz), and 5 dB re 1 microPa2/Hz @ 1 m at high frequencies (10,000 Hz). Below 200 Hz, the class-specific median spectrum levels bifurcate with large commercial ships grouping as higher power noise sources. Within all ship classes spectrum levels vary more at low frequencies than at high frequencies, and the degree of variability is almost halved for classes that have smaller speed standard deviations.

scholarly journals Ship noise in an urban estuary extends to frequencies used for echolocation by endangered killer whales

2015 ◽  
Author(s):  
Scott Veirs ◽  
Val Veirs ◽  
Jason D Wood
Keyword(s):  
Transmission Loss ◽  
Source Spectrum ◽  
Automatic Identification ◽  
Identification System ◽  
Underwater Sound ◽  
Killer Whales ◽  
Noise Sources ◽  
Low Frequencies ◽  
High Frequencies ◽  
Location Data

Combining calibrated hydrophone measurements with vessel location data from the Automatic Identification System, we estimate underwater sound pressure levels for 1,582 unique ships that transited the core critical habitat of the endangered Southern Resident killer whales during 28 months between March, 2011, and October, 2013. Median received spectrum levels of noise from 2,812 isolated transits are elevated relative to median background levels not only at low frequencies (20-30 dB re 1 μPa2/Hz from 100-1000 Hz), but also at high frequencies (5-13 dB re 1 μPa2/Hz from 10,000-96,000 Hz). Thus, noise received from ships at ranges less than 3 km extends to frequencies used by odontocetes like the southern resident killer whales for communication and echolocation. Broadband received levels (11.5-40,000 Hz) near the shoreline in Haro Strait (WA, USA) for the entire ship population were 111 ± 6 dB re 1 μPa on average. Mean ship speed was 14.4 ± 4.1 knots. Most ship classes show a linear relationship between received level and speed with a slope near +1 dB/knot. Assuming near-spherical spreading based on a transmission loss experiment we compute mean broadband source levels for the ship population of 173 ± 7 dB re 1 μPa @ 1 m without accounting for frequency-dependent absorption. Spectrum, 1/12- octave, and 1/3-octave source levels for the whole population have median values that are comparable to previous measurements and models at most frequencies, but for select studies may be relatively low below 200 Hz and high above 20,000 Hz. Median source spectrum levels peak near 50 Hz for all 12 ship classes, have a maximum of 159 dB re 1 μPa2/Hz @ 1 m for container ships, and vary between classes by about 25 dB re 1 μPa2/Hz @ 1 m at low frequencies (50 Hz), 13 dB re 1 μPa2/Hz @ 1 m at mid-frequencies (1,000 Hz), and 5 dB re 1 μPa2/Hz @ 1 m at high frequencies (10,000 Hz). Below 200 Hz, the class-specific median spectrum levels bifurcate with large commercial ships grouping as higher power noise sources. Within all ship classes spectrum levels vary more at low frequencies than at high frequencies, and the degree of variability is almost halved for classes that have smaller speed standard deviations.

scholarly journals Ship noise extends to frequencies used for echolocation by endangered killer whales

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1657 ◽  
Author(s):  
Scott Veirs ◽  
Val Veirs ◽  
Jason D. Wood
Keyword(s):  
Transmission Loss ◽  
Source Spectrum ◽  
Automatic Identification ◽  
Identification System ◽  
Underwater Sound ◽  
Killer Whales ◽  
Noise Sources ◽  
Low Frequencies ◽  
High Frequencies ◽  
Location Data

Combining calibrated hydrophone measurements with vessel location data from the Automatic Identification System, we estimate underwater sound pressure levels for 1,582 unique ships that transited the core critical habitat of the endangered Southern Resident killer whales during 28 months between March, 2011, and October, 2013. Median received spectrum levels of noise from 2,809 isolated transits are elevated relative to median background levels not only at low frequencies (20–30 dB re 1 µPa2/Hz from 100 to 1,000 Hz), but also at high frequencies (5–13 dB from 10,000 to 96,000 Hz). Thus, noise received from ships at ranges less than 3 km extends to frequencies used by odontocetes. Broadband received levels (11.5–40,000 Hz) near the shoreline in Haro Strait (WA, USA) for the entire ship population were 110 ± 7 dB re 1 µPa on average. Assuming near-spherical spreading based on a transmission loss experiment we compute mean broadband source levels for the ship population of 173 ± 7 dB re 1 µPa 1 m without accounting for frequency-dependent absorption. Mean ship speed was 7.3 ± 2.0 m/s (14.1 ± 3.9 knots). Most ship classes show a linear relationship between source level and speed with a slope near +2 dB per m/s (+1 dB/knot). Spectrum, 1/12-octave, and 1/3-octave source levels for the whole population have median values that are comparable to previous measurements and models at most frequencies, but for select studies may be relatively low below 200 Hz and high above 20,000 Hz. Median source spectrum levels peak near 50 Hz for all 12 ship classes, have a maximum of 159 dB re 1 µPa2/Hz @ 1 m for container ships, and vary between classes. Below 200 Hz, the class-specific median spectrum levels bifurcate with large commercial ships grouping as higher power noise sources. Within all ship classes spectrum levels vary more at low frequencies than at high frequencies, and the degree of variability is almost halved for classes that have smaller speed standard deviations. This is the first study to present source spectra for populations of different ship classes operating in coastal habitats, including at higher frequencies used by killer whales for both communication and echolocation.

scholarly journals Ship noise in an urban estuary extends to frequencies used for echolocation by endangered killer whales

2015 ◽  
Author(s):  
Scott Veirs ◽  
Val Veirs ◽  
Jason D Wood
Keyword(s):  
Transmission Loss ◽  
Source Spectrum ◽  
Automatic Identification ◽  
Identification System ◽  
Underwater Sound ◽  
Killer Whales ◽  
Noise Sources ◽  
Low Frequencies ◽  
High Frequencies ◽  
Location Data

Combining calibrated hydrophone measurements with vessel location data from the Automatic Identification System, we estimate underwater sound pressure levels for 1,582 unique ships that transited the core critical habitat of the endangered Southern Resident killer whales during 28 months between March, 2011, and October, 2013. Median received spectrum levels of noise from 2,812 isolated transits are elevated relative to median background levels not only at low frequencies (20-30 dB re 1 mPa2/Hz from 100-1000 Hz), but also at high frequencies (5-13 dB re 1 mPa2/Hz from 10,000-96,000 Hz). Thus, noise received from ships at ranges less than 3 km extends to frequencies used by odontocetes like the Southern Resident orcas for communication and echolocation. Broadband received levels (20-96,000 Hz) near the shoreline in Haro Strait (WA, USA) for the entire ship population were 111 ± 6 dB re 1 mPa on average. Mean ship speed was 14.4 ± 4.1 knots. Most ship classes show a linear relationship between received level and speed with a slope near +1 dB/knot. Assuming near-spherical spreading based on a transmission loss experiment, we compute mean broadband source levels for the ship population of 173 ± 7 dB re 1 mPa @ 1 m without accounting for frequency-dependent absorption, and 177± 13 dB re 1 mPa @ 1 m with absorption. Spectrum, 1/12-octave, and 1/3-octave source levels for the whole population have median values that are comparable to previous measurements and models at most frequencies, but for select studies may be relatively low below 200 Hz and high above 20,000 Hz. Median source spectrum levels (without accounting for absorption) peak near 50 Hz for all 12 ship classes, have a maximum of 159 dB re 1 mPa2=Hz @ 1 m for container ships, and vary between classes by over 25 dB re 1 mPa2=Hz @ 1 m at low frequencies (50 Hz), 10 dB re 1 mPa2=Hz @ 1 m at mid-frequencies (1,000 Hz), and about 5 dB re 1 mPa2=Hz @ 1 m at high frequencies (10,000 Hz). Below 200 Hz, the class-specific median spectrum levels bifurcate with large commercial ships grouping as higher power noise sources. Within all ship classes spectrum levels vary more at low frequencies than at high frequencies, and the degree of variability is almost halved for classes that have smaller speed standard deviations.

scholarly journals Ship noise in an urban estuary extends to frequencies used for echolocation by endangered killer whales

2015 ◽  
Author(s):  
Scott Veirs ◽  
Val Veirs ◽  
Jason D Wood
Keyword(s):  
Transmission Loss ◽  
Source Spectrum ◽  
Automatic Identification ◽  
Identification System ◽  
Underwater Sound ◽  
Killer Whales ◽  
Noise Sources ◽  
Low Frequencies ◽  
High Frequencies ◽  
Location Data

Combining calibrated hydrophone measurements with vessel location data from the Automatic Identification System, we estimate underwater sound pressure levels for 1,582 unique ships that transited the core critical habitat of the endangered Southern Resident killer whales during 28 months between March, 2011, and October, 2013. Median received spectrum levels of noise from 2,812 isolated transits are elevated relative to median background levels not only at low frequencies (20-30 dB re 1 μPa2/Hz from 100-1000 Hz), but also at high frequencies (5-13 dB re 1 μPa2/Hz from 10,000-96,000 Hz). Thus, noise received from ships at ranges less than 3 km extends to frequencies used by odontocetes like the southern resident killer whales for communication and echolocation. Broadband received levels (11.5-40,000 Hz) near the shoreline in Haro Strait (WA, USA) for the entire ship population were 111 ± 6 dB re 1 μPa on average. Mean ship speed was 14.4 ± 4.1 knots. Most ship classes show a linear relationship between received level and speed with a slope near +1 dB/knot. Assuming near-spherical spreading based on a transmission loss experiment we compute mean broadband source levels for the ship population of 173 ± 7 dB re 1 μPa @ 1 m without accounting for frequency-dependent absorption. Spectrum, 1/12- octave, and 1/3-octave source levels for the whole population have median values that are comparable to previous measurements and models at most frequencies, but for select studies may be relatively low below 200 Hz and high above 20,000 Hz. Median source spectrum levels peak near 50 Hz for all 12 ship classes, have a maximum of 159 dB re 1 μPa2/Hz @ 1 m for container ships, and vary between classes by about 25 dB re 1 μPa2/Hz @ 1 m at low frequencies (50 Hz), 13 dB re 1 μPa2/Hz @ 1 m at mid-frequencies (1,000 Hz), and 5 dB re 1 μPa2/Hz @ 1 m at high frequencies (10,000 Hz). Below 200 Hz, the class-specific median spectrum levels bifurcate with large commercial ships grouping as higher power noise sources. Within all ship classes spectrum levels vary more at low frequencies than at high frequencies, and the degree of variability is almost halved for classes that have smaller speed standard deviations.

Synthesis of a multicomponent silica aerogel-containing nanocomposite for efficient sound absorption properties

2021 ◽  
pp. 096739112098574
Author(s):  
Mansoureh Hamidi ◽  
Parvin Nassiri ◽  
Homayoon Ahmad Panahi ◽  
Lobat Taghavi ◽  
Saeed Bazgir
Keyword(s):  
Silica Aerogel ◽  
Sound Absorption ◽  
Sound Pressure ◽  
Transmission Loss ◽  
Pressure Level ◽  
Tube Model ◽  
Absorption Properties ◽  
Low Frequencies ◽  
High Frequencies ◽  
Optimum Sample

In this study, the sound properties of four types of nanocomposites have been investigated. To this end, the prepared samples were measured by the impedance tube model BSWA-SW 422, SW477. It was found that the Sound Absorption Coefficient (SAC) of all samples was increased at high frequencies relatively well. The highest SAC at medium and low frequencies was related to the nanocomposite D. The results of sound Transmission Loss (TL) of nanocomposites showed that the TL value for the nanocomposite D (optimum sample) was higher at all frequencies compared to other nanocomposites. The results confirmed that adding organic and mineral materials to the silica aerogel (SA) simultaneously improves its sound properties. By measuring the Sound Pressure Level (SPL) around the enclosure without optimum sample and with optimum sample in the four sound ranges, we found that using nanocomposite D can significantly reduce the noise. According to this study, SA/polyester nonwoven layer/pan nanofibers/nanoclay nanocomposite (nanocomposites D) have great sound absorption properties, which can be used in different environments.

scholarly journals Slower Ship Speed in the Bahamas Due to COVID-19 Produces a Dramatic Reduction in Ocean Sound Levels

2021 ◽  
Vol 8 ◽  
Author(s):  
Charlotte Dunn ◽  
James Theriault ◽  
Leigh Hickmott ◽  
Diane Claridge
Keyword(s):  
Sperm Whale ◽  
Mitigation Measures ◽  
Automatic Identification ◽  
Identification System ◽  
Density Level ◽  
Underwater Sound ◽  
Sperm Whales ◽  
Ship Traffic ◽  
Sound Levels ◽  
Ship Speed

As underwater noise from ship traffic increases, profound effects on the marine environment highlight the need for improved mitigation measures. One measure, reduction in ship speed, has been shown to be one of the key drivers in reducing sound source levels of vessels. In 2017, a study began to assess the impacts of increasing commercial shipping traffic on sperm whales in Northwest Providence Channel, northern Bahamas, an international trade route that primarily serves the southeast US. Ship data were collected from an Automatic Identification System (AIS) station combined with recordings from an acoustic recorder to measure underwater sound levels and to detect the presence of sperm whales. Here we analyze a subset of these data to opportunistically investigate potential changes in ship traffic before and during the COVID-19 pandemic. These data span one calendar year from October 2019 to October 2020. A pre-COVID-19 dataset of 121 days, from a recorder approximately 2 km from the shipping route was compared to a 134-day dataset collected during COVID-19 from the same site, comprising 2900 and 3181 ten-minute recordings, respectively. A dramatic decrease in ocean noise levels concurrent with changes in shipping activity occurred during the pandemic. The mean pre-COVID-19 power density level in the 111–140 Hz 1/3-octave band was 88.81 dB re 1 μPa (range 81.38–100.90) and decreased to 84.27 dB re 1 μPa (range 78.60–99.51) during COVID-19, equating to a 41% reduction in sound pressure levels (SPL). After differences in seasonal changes in wind speed were accounted for, SPL decreased during the pandemic by 3.98 dB (37%). The most notable changes in ship activity were significantly reduced vessel speeds for all ship types and fewer ships using the area during the pandemic. Vessel speed was highly correlated to SPL and the only ship-based variable that predicted SPLs. Despite the opportunistic nature [i.e., not a standard before-after-control-impact (BACI) study], this study provides a unique opportunity to assess the effectiveness of ship traffic management strategies, such as slowing ships down, to mitigate impacts on marine life in the study area, including local sperm whale populations.

scholarly journals Detection, Localization and Classification of Multiple Mechanized Ocean Vessels over Continental-Shelf Scale Regions with Passive Ocean Acoustic Waveguide Remote Sensing

2018 ◽  
Vol 10 (11) ◽  
pp. 1699 ◽  
Author(s):  
Chenyang Zhu ◽  
Heriberto Garcia ◽  
Anna Kaplan ◽  
Matthew Schinault ◽  
Nils Handegard ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Continental Shelf ◽  
Signal To Noise Ratio ◽  
Automatic Identification ◽  
Identification System ◽  
Underwater Sound ◽  
Constant Frequency ◽  
Acoustic Waveguide ◽  
Time Frequency ◽  
Hydrophone Array

Multiple mechanized ocean vessels, including both surface ships and submerged vehicles, can be simultaneously monitored over instantaneous continental-shelf scale regions >10,000 km 2 via passive ocean acoustic waveguide remote sensing. A large-aperture densely-sampled coherent hydrophone array system is employed in the Norwegian Sea in Spring 2014 to provide directional sensing in 360 degree horizontal azimuth and to significantly enhance the signal-to-noise ratio (SNR) of ship-radiated underwater sound, which improves ship detection ranges by roughly two orders of magnitude over that of a single hydrophone. Here, 30 mechanized ocean vessels spanning ranges from nearby to over 150 km from the coherent hydrophone array, are detected, localized and classified. The vessels are comprised of 20 identified commercial ships and 10 unidentified vehicles present in 8 h/day of Passive Ocean Acoustic Waveguide Remote Sensing (POAWRS) observation for two days. The underwater sounds from each of these ocean vessels received by the coherent hydrophone array are dominated by narrowband signals that are either constant frequency tonals or have frequencies that waver or oscillate slightly in time. The estimated bearing-time trajectory of a sequence of detections obtained from coherent beamforming are employed to determine the horizontal location of each vessel using the Moving Array Triangulation (MAT) technique. For commercial ships present in the region, the estimated horizontal positions obtained from passive acoustic sensing are verified by Global Positioning System (GPS) measurements of the ship locations found in a historical Automatic Identification System (AIS) database. We provide time-frequency characterizations of the underwater sounds radiated from the commercial ships and the unidentified vessels. The time-frequency features along with the bearing-time trajectory of the detected signals are applied to simultaneously track and distinguish these vessels.

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