1887
banner image
No data available.
Please log in to see this content.
You have no subscription access to this content.
No metrics data to plot.
The attempt to load metrics for this article has failed.
The attempt to plot a graph for these metrics has failed.
Long-time trends in ship traffic noise for four sites off the North American West Coast
Rent:
Rent this article for
USD
10.1121/1.3518770
/content/asa/journal/jasa/129/2/10.1121/1.3518770
http://aip.metastore.ingenta.com/content/asa/journal/jasa/129/2/10.1121/1.3518770

Figures

Image of FIG. 1.
FIG. 1.

Receivers described in this report.

Image of FIG. 2.
FIG. 2.

Typical data acquisition system. The PC represents an Intel class personal computer. The nature of the removable media has changed as technology has evolved.

Image of FIG. 3.
FIG. 3.

Spectrograms for all systems, all available records, and composite time streams. The color scale is in decibels relative to the site median spectrum. Gaps indicate system outages. Each vertical raster line is the decibel average of 24 h of PSD estimates minus the site median spectrum.

Image of FIG. 4.
FIG. 4.

Cumulative level distributions, all systems, and composite time streams. System d: 6 yr of data (393718 spectra.) System f: 12 yr of data (557330 spectra.) System g: 12 yr of data (688 728 spectra.) System h: 12 yr of data (171318 spectra.) (System h curves do not use questionable data from February 1997 to August 2003, see Fig. 8.).

Image of FIG. 5.
FIG. 5.

Trends for the reduced composite stream, all traffic noise bands, system d. Trend line is bold. Trends for constituent time streams A, B, and C included for comparison.

Image of FIG. 6.
FIG. 6.

Trends for the reduced composite stream, all traffic noise bands, system f. Trend line is bold. Trends for constituent time streams A, B, and C included for comparison.

Image of FIG. 7.
FIG. 7.

Trends for the reduced composite stream, all traffic noise bands, system g. Trend line is bold. Trends for constituent time streams A, B, and C included for comparison.

Image of FIG. 8.
FIG. 8.

Trends for the reduced composite stream, all traffic noise bands, system h. Trend line is bold. Trends for constituent time streams A, B, and C included for comparison. System hardware malfunctions contributed to data contamination from February 1998 to August 2003, particularly evident at 40 and 50 Hz. (Contamination was worst around 60 Hz.) Trend lines did not use levels from this period.

Image of FIG. 9.
FIG. 9.

Historical and contemporary traffic noise levels. The historical “summary” points at 1965 are from Table II. Solid lines represent the model fits to the APL/UW data, shown over the temporal span of the actual dataset. Thin dotted lines connect measurements for the same band for each system. The heavy dashed line indicates the trend suggested by Ross, which was based broadly on data from many systems in both the Atlantic and Pacific, and not specifically on data from the systems used in the present study.

Tables

Generic image for table
TABLE I.

Simplified categorization of OTO bands by dominant processes. f c is the approximate OTO band center frequency. Band center frequencies and band edges in Hertz.

Generic image for table
TABLE II.

Average levels, all bands analyzed, including historical (Wenz,5 1963–1965) and contemporary (APL/UW, 1994–2007) values, and the difference Δ. Approximate band center frequency shown under the band. Levels are in decibels with reference value 1 μPa2/Hz; level Δ in decibels. Questionable data from system h has been excluded (see Fig. 8.) All APL/UW values utilized the composite time stream. Values in parentheses are approximate errors (see text).

Generic image for table
TABLE III.

Simple trend parameters, all traffic noise bands, and reduced composite time streams. Approximate band center frequency shown under the band. Epoch is the first time in the record, given as year followed by yearday (where 1st January is yearday 1). Epoch level is in decibels with reference value 1 μPa2/Hz. Slope is in decibels per year. Range is the minimum and maximum slope across all constituent time streams.

Loading

Article metrics loading...

/content/asa/journal/jasa/129/2/10.1121/1.3518770
2011-02-24
2014-04-17
Loading

Full text loading...

This is a required field
Please enter a valid email address
752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Long-time trends in ship traffic noise for four sites off the North American West Coast
http://aip.metastore.ingenta.com/content/asa/journal/jasa/129/2/10.1121/1.3518770
10.1121/1.3518770
SEARCH_EXPAND_ITEM