Linked Life Data

15810696

Source:http://linkedlifedata.com/resource/pubmed/id/15810696

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3 Pt 2
pubmed:dateCreated
2005-4-6
pubmed:abstractText
We examine statistical and directional properties of the ambient noise in the 10-100 Hz frequency band from the NPAL array. Marginal probability densities are estimated as well as mean square levels, skewness and kurtoses in third octave bands. The kurotoses are markedly different from Gaussian except when only distant shipping is present. Extremal levels reached approximately 150 dB re 1 micro Pa, suggesting levels 60dB greater than the mean ambient were common in the NPAL data sets. Generally, these were passing ships. We select four examples: i) quiescent noise, ii) nearby shipping, iii) whale vocalizations and iv) a micro earthquake for the vertical directional properties of the NPAL noise since they are representative of the phenomena encountered. We find there is modest broadband coherence for most of these cases in their occupancy band across the NPAL aperture. Narrowband coherence analysis from VLA to VLA was not successful due to ambiguities. Examples of localizing sources based upon this coherence are included. kw diagrams allow us to use data above the vertical aliasing frequency. Ducted propagation for both the quiescent and micro earthquake (T phase) are identified and the arrival angles of nearby shipping and whale vocalizations. MFP localizations were modestly successful for nearby sources, but long range ones could not be identified, most likely because of signal mismatch in the MFP replica.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0001-4966
pubmed:author
pubmed:issnType
Print
pubmed:volume
117
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1643-65
pubmed:dateRevised
2009-6-26
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Statistics and vertical directionality of low-frequency ambient noise at the North Pacific Acoustic Laboratory site.
pubmed:affiliation
Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S.