Characterization of anthropogenic noise and oyster toadfish (Opsanus tau) calling behavior in urban and small-town coastal soundscapesa).

The oyster toadfish (Opsanus tau) is an ideal model to examine the effects of anthropogenic noise on behavior because they rely on acoustic signals for mate attraction and social interactions. We predict that oyster toadfish have acclimated to living in noise-rich environments because they are common in waterways of urban areas, like New York City (NYC). We used passive acoustic monitoring at two locations to see if calling behavior patterns are altered in areas of typically high boat traffic versus low boat traffic (Pier 40, NYC, NY, and Eel Pond, Woods Hole, MA, respectively).

Temporal coherence of harmonic frequencies affects echo detection in the big brown bat, Eptesicus fuscus.

Echolocating big brown bats (Eptesicus fuscus) broadcast frequency modulated (FM) ultrasonic pulses containing two prominent harmonic sweeps (FM1, FM2). Both harmonics typically return as echoes at the same absolute time delay following the broadcast, making them coherent. Electronically splitting FM1 and FM2 allows their time delays to be controlled separately, making them non-coherent.

Testosterone Treatment Mimics Seasonal Downregulation of Dopamine Innervation in the Auditory System of Female Midshipman Fish.

In seasonally breeding vertebrates, hormones coordinate changes in nervous system structure and function to facilitate reproductive readiness and success. Steroid hormones often exert their effects indirectly via regulation of neuromodulators, which in turn can coordinate the modulation of sensory input with appropriate motor output. Female plainfin midshipman fish (Porichthys notatus) undergo increased peripheral auditory sensitivity in time for the summer breeding season, improving their ability to detect mates, which is regulated by steroid hormones.

Spatiotemporal patterning of acoustic gaze in echolocating bats navigating gaps in clutter.

We challenged four big brown bats to maneuver through abrupt turns in narrow corridors surrounded by dense acoustic clutter. We quantified bats' performance, sonar beam focus, and sensory acquisition rate. Performance was excellent in straight corridors, with sonar beam aim deviating less than 5° from the corridor midline.

Big brown bats (Eptesicus fuscus) successfully navigate through clutter after exposure to intense band-limited sound.

Echolocating big brown bats fly, orient, forage, and roost in cluttered acoustic environments in which aggregate sound pressure levels can be as intense as 100 to 140 dB SPL, levels that would impair auditory perception in other terrestrial mammals. We showed previously that bats exposed to intense wide-band sound (116 dB SPL) can navigate successfully through dense acoustic clutter. Here, we extend these results by quantifying performance of bats navigating through a cluttered scene after exposure to intense band-limited sounds (bandwidths 5-25 kHz, 123 dB SPL).

Big brown bats (Eptesicus fuscus) maintain hearing sensitivity after exposure to intense band-limited noise.

Thresholds to short-duration narrowband frequency-modulated (FM) sweeps were measured in six big brown bats (Eptesicus fuscus) in a two-alternative forced choice passive listening task before and after exposure to band-limited noise (lower and upper frequencies between 10 and 50 kHz, 1 h, 116-119 dB sound pressure level root mean square; sound exposure level 152 dB). At recovery time points of 2 and 5 min post-exposure, thresholds varied from -4 to +4 dB from pre-exposure threshold estimates. Thresholds after sham (control) exposures varied from -6 to +2 dB from pre-exposure estimates.

Echolocation behavior in big brown bats is not impaired after intense broadband noise exposures.

Echolocating bats emit trains of intense ultrasonic biosonar pulses and listen to weaker echoes returning from objects in their environment. Identification and categorization of echoes are crucial for orientation and prey capture. Bats are social animals and often fly in groups in which they are exposed to their own emissions and to those from other bats, as well as to echoes from multiple surrounding objects.

Broadband noise exposure does not affect hearing sensitivity in big brown bats (Eptesicus fuscus).

In many vertebrates, exposure to intense sounds under certain stimulus conditions can induce temporary threshold shifts that reduce hearing sensitivity. Susceptibility to these hearing losses may reflect the relatively quiet environments in which most of these species have evolved. Echolocating big brown bats (Eptesicus fuscus) live in extremely intense acoustic environments in which they navigate and forage successfully, both alone and in company with other bats.