North Pacific right whale up-call source levels and propagation distance on the southeastern Bering Sea shelf
ARP deployment locations (asterisks) in 2000-2002 and dotted bathymetric contours (from Smith and Sandwell, 1997) in the SEBS.
(Color online). Right whale up-call recorded at ARP sites A, B, and C. A second call from an unidentified species was recorded on C. Sample frequency F s = 500 Hz, FFT and Hanning window length = 250 points for 0.5 s window length, overlap = 98%. Same intensity of color-scale across spectrograms.
(Color online). Spectrograms of a single right whale call received on two easternmost ARPs (site C and D), with overlaid normal mode arrivals of synthetic call based on range estimates, given above each call. Figure adapted with permission from Wiggins et al. (2004) in Canadian Acoustics.
Call rms received levels (dB re 1 μPa) plotted vs log10(r), where r is the distance to the hydrophone. (A) Ranges calculated using TDOA localization; each call is represented by a unique symbol and distances are plotted on three or four receivers. (B) Ranges calculated using NMDM. Linear regression (dashed line) equations and R 2 values are displayed in upper right of each panel. Note that source level (Table I) does not equal the y-intercept of the linear regression, due to the additional term for spherical spreading loss over the first 70 m of propagation (one water depth).
Histograms of estimated call source levels, equal to received level plus transmission loss, using ranges based on TDOA (left) and NMDM (right), for (A) peak-to-peak and (B) root-mean-square measurements. (C) Estimated SEL for same data sets.
Ambient noise average within 100–150 Hz band at site C, first week of recording, October 2000. Figure adapted with permission from Munger et al. (2005) in Canadian Acoustics.
Comparison of NMDM and TDOA range estimates for right whale calls received on multiple instruments (calls with visible mode arrivals only).
Linear regression coefficients and R 2 value, average sound levels, and sample size (n) for peak-to-peak and rms source levels and SEL, using the two different ranging methods: TDOA and NMDM. Received level: RL = SL – TL = – x log10(r) + b
Article metrics loading...
Full text loading...