1. There is strong socio-political support for offshore wind development in US territorial waters and construction is planned off several east coast states. Some of the planned development sites coincide with important habitat for critically endangered North Atlantic right whales. Both exclusion zones and passive acoustic monitoring are important tools for managing interactions between marine mammals and human activities. Understanding where animals are with respect to exclusion zones is important to avoid costly construction delays while minimizing the potential for negative impacts. Impact piling from construction of hundreds of offshore wind turbines likely require exclusion zones as large as 10 km.2. We have developed a three-hydrophone passive acoustic monitoring system that provides bearing information along with marine mammal detections to allow for informed management decisions in real-time. Multiple units form a monitoring system designed to determine whether marine mammal calls originate from inside or outside of an exclusion zone. In October 2021, we undertook a full system validation, with a focus on evaluating the detection range and bearing accuracy of the system with respect to right whale upcalls. Five units were deployed in Mid-Atlantic waters and we played more than 3500 simulated right whale upcalls at known locations to characterize the detection function and bearing accuracy of each unit. The modelled results of the detection function error were then used to compare the effectiveness of a bearing-based system to a single sensor that can only detect a signal but not ascertain directivity.3. Field trials indicated maximum detection ranges from 4-7.3 km depending on source and ambient noise levels. Simulations showed that incorporating bearing detections provide a substantial improvement in false alarm rates (6 to 12 times depending on number of units, placement and signal to noise conditions) for a small increase in the risk of missed detections inside of an exclusion zone (1%-3%).4. We show that the system can be used for monitoring exclusion zones and clearly highlight the value of including bearing estimation into exclusion zoneThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

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We present experimental measurements of the resonances of guitar top plates using a speckle pattern interferometer. The studies include sanded spruce starting materials of different grades and finished commercial guitars. The spruce top plates consist of three different wood grades reflecting the quality of the wood grain. The normal mode frequencies and patterns are measured without sides to be consistent with the tap tones a Luthier would use to determine the quality of the top plate. We will discuss the ways in which the wood grade changes the frequency and distribution of normal mode frequencies due to variations in the grains of the raw wood. We will also compare these results to measurements on commercial guitar top plates.

A recent Incidental Harassment Authorization requires a 10 km zone to be monitored with passive acoustics before and during pile driving. SMRU Consulting has built the Coastal Acoustic Buoy for Offshore Wind (CABOW) to address this need. Each CABOW consists of: a bottom lander with three hydrophones; data acquisition system; and onboard computer running PAMGuard. The CABOW detects potential calls and relays clips to a base station for classification, bearing estimation, and validation. Bench testing characterized detector performance and measured bearing accuracy as a function of SNR. Field trials used playbacks of real and simulated right whale upcalls to evaluate the detection probability with respect to the range and signal excess of the call; estimate bearing accuracy; and test the range and stability of the radio communications. Field trials indicated a maximum detection range of 4–12 km under high and very low noise levels, respectively. Finally, we used a simulation to compare true and false alarm rates of the CABOW to an equivalent single sensor system for monitoring a fixed area. Simulations show that incorporating bearings to calling animals could provide a substantial improvement in false alarm rates relative to single sensors if properly placed with respect to potential noise sources.