Mechanisms of auditory masking in marine mammals

Abstract

Anthropogenic noise is an increasing threat to marine mammals that rely on sound for communication, navigation, detecting prey and predators, and finding mates. Auditory masking is one consequence of anthropogenic noise, the study of which is approached from multiple disciplines including field investigations of animal behavior, noise characterization from in-situ recordings, computational modeling of communication space, and hearing experiments conducted in the laboratory. This paper focuses on laboratory hearing experiments applying psychophysical methods, with an emphasis on the mechanisms that govern auditory masking. Topics include tone detection in simple, complex, and natural noise; mechanisms for comodulation masking release and other forms of release from masking; the role of temporal resolution in auditory masking; and energetic vs informational masking.

Directional hydrophone clusters reveal evasive responses of small cetaceans to disturbance during construction at offshore windfarms

“…Piling noise is predominantly low frequency [15] and porpoise hearing is most sensitive at high frequencies [27]. Audibility of both the ADD and piling would have been dependent both on environmental conditions [28] and on the level above the porpoise hearing threshold [8]. When filtered using the harbour porpoise audiogram and compared to both background noise and the porpoise hearing threshold, our data indicate that the sound of the piling soft start was likely to be audible to a range of at least 10 km.…”

Communication in Cook Inlet beluga whales: Describing the vocal repertoire and masking of calls by commercial ship noise

“…Our study provides empirical support that all seven of the most common call types in the CIB vocal repertoire were partially masked by distant commercial ship noise and completely masked by close commercial ship noise in the frequency range up to 12 kHz. Auditory masking occurs when one sound interferes with an individual's ability to not only detect, but also discriminate and recognize another sound (Branstetter and Sills, 2022;Erbe et al, 2016). While some beluga calls can have acoustic energy above 12 kHz, the crucial components of the calls below 12 kHz will be masked and the animal's ability to discriminate, recognize, and process the encoded information will be impacted.…”

“…The masking of vocalizations by commercial shipping noise, and consequently the disruption of communication, could be one of the main underlying mechanisms of anthropogenic impact. Anthropogenic noise can negatively affect marine mammals in a multitude of ways, including temporary or permanent hearing threshold shifts, changes in behavior, and auditory masking (Branstetter and Sills, 2022;DeRuiter et al, 2013;Finneran, 2015;Holt et al, 2011;Martin et al, 2023;Parsons, 2017;Tyack and Janik, 2013). Auditory masking is often considered the most prevalent and occurs when one sound interferes with an individual's ability to detect and discriminate another sound (Branstetter and Sills, 2022;Erbe et al, 2016).…”

Moderate Anthropogenic Noise Exposure Does Not Affect Navy Bottlenose Dolphin (Tursiops truncatus) Whistle Rates

“…Masking occurs when one sound (e.g., noise) interferes with a listener's ability to hear or interpret a signal (e.g., a whistle from a conspecific) [30,[44][45][46][47]. Masking can reduce the communication space available to an animal, with the severity of the masking dependent on the masker amplitude, similarities between the noise and signal in frequency and time, the position of the listener relative to the sound sources, and the signal-detection capabilities of the animal (e.g., critical ratio) [46]. Anti-masking responses by cetaceans have included increasing the amplitude of their call (i.e., the Lombard effect) [48,49], changing the duration of their calls, and/or changing their call rate [50][51][52].…”