Abstract
Measurements of radiated noise from offshore wind construction activity were collected on four bottom-mounted hydrophone arrays during May-August 2024 on the southern New England continental shelf. Calibrated source operations using a J-13 acoustic projector were conducted after completion of construction in September 2024 to quantify North Atlantic right whale (NARW) upcall detector-classifier performance and measure transmission loss at the site. Comparison of 32-channel array and omni-directional hydrophone detection performance reveals a nearly four-fold detection range advantage for the array in this 17logR TL environment. The calibrated source results were then used to validate the hypothesis that NARW upcall detection is a narrowband, rather than broadband, detection problem—the effective noise bandwidth (ENBW) employed in the sonar equation is linked to the mean instantaneous bandwidth of the upcall, empirically determined to be 12 Hz for a recognition differential of 5.5 dB. This finding has important implications for extrapolation of upcall detection performance models to new noise environments. Measurements of pile driving noise power spectra and array gain in third octave bands, as well as beam noise bearing dependence during pile driving, will be presented. These noise measurements, coupled with the narrowband ENBW definition, are then employed to predict upcall detection range for an array in the presence of pile driving.