Anti-masking strategies include, but are not limited to, the Lombard effect (e.g., Holt et al. The study of auditory masking in marine mammals can be divided into three primary categories, the first being behavioral response studies evaluating whether animals change their behavior to presumably mitigate auditory masking (Holt et al. 2016).Īuditory masking can be defined as “the process by which the threshold of hearing for one sound is raised by the presence of another (masking) sound and the amount by which the threshold of hearing for one sound is raised by the presence of another (masking) sound, expressed in dB” (American National Standard Institute (ANSI) 1995). 2009) and auditory masking (for review, see Erbe et al.

2020) changes in behavior that may affect individual fitness (e.g., Southall et al. Negative impacts from anthropogenic noise can include physical discomfort, pain, or death (e.g., Parsons 2017) permanent and temporary thresholds shifts in hearing sensitivity (e.g., Finneran 2015) increased stress (e.g., Wright et al. Noise sources include transportation (e.g., shipping, aircraft, icebreakers), construction (e.g., dredging, pile driving), geophysical surveys (e.g., airgun arrays), military (e.g., sonars, explosives), and ocean science surveys (e.g., seismology, acoustic tomography) (Richardson et al. However, there has been a dramatic increase in anthropogenic noise since the industrial revolution (see Richardson et al. Non-biological and biological sounds have been part of the ocean’s soundscape for millions of years and marine mammals have evolved to be acoustic specialists in this environment. Biological noise comprises any sounds that living organisms produce, such as snapping shrimp snaps, animal vocalizations, and sounds generated by physical interactions with the environment (e.g., fish chewing coral and whales slapping the water's surface). One type of noise source is non-biological, which includes wind, rain, ice movement, tides, and seismic events.

Anything that produces sound is a potential noise source (for a review, see Richardson et al. The marine environment has always been noisy, because sound travels exceptionally well in ocean environments. When one sound interferes with a listener’s ability to detect, discriminate, or recognize another sound, auditory masking occurs. Auditory masking in marine mammals has garnered attention in recent years due to an increased awareness of the negative effects of anthropogenic noise on hearing.

Masking dredging data research