http://ieeexplore.ieee.org/iel5/5/31047/01444179.pdf

Fundamentals of acoustics

Global increases in environmental noise levels – arising from expansion of human populations, transportation networks, and resource extraction – have catalysed a recent surge of research into the effects of noise on wildlife. Synthesising a coherent understanding of the biological consequences of noise from this literature is challenging. Taxonomic groups vary in auditory capabilities. A wide range of noise sources and exposure levels occur, and many kinds of biological responses have been observed, ranging from individual behaviours to changes in ecological communities. Also, noise is one of several environmental effects generated by human activities, so researchers must contend with potentially confounding explanations for biological responses. Nonetheless, it is clear that noise presents diverse threats to species and ecosystems and salient patterns are emerging to help inform future natural resource-management decisions. We conducted a systematic and standardised review of the scientific literature published from 1990 to 2013 on the effects of anthropogenic noise on wildlife, including both terrestrial and aquatic studies. Research to date has concentrated predominantly on European and North American species that rely on vocal communication, with approximately two-thirds of the data set focussing on songbirds and marine mammals. The majority of studies documented effects from noise, including altered vocal behaviour to mitigate masking, reduced abundance in noisy habitats, changes in vigilance and foraging behaviour, and impacts on individual fitness and the structure of ecological communities. This literature survey shows that terrestrial wildlife responses begin at noise levels of approximately 40 dBA, and 20% of papers documented impacts below 50 dBA. Our analysis highlights the utility of existing scientific information concerning the effects of anthropogenic noise on wildlife for predicting potential outcomes of noise exposure and implementing meaningful mitigation measures. Future research directions that would support more comprehensive predictions regarding the magnitude and severity of noise impacts include: broadening taxonomic and geographical scope, exploring interacting stressors, conducting larger-scale studies, testing mitigation approaches, standardising reporting of acoustic metrics, and assessing the biological response to noise-source removal or mitigation. The broad volume of existing information concerning the effects of anthropogenic noise on wildlife offers a valuable resource to assist scientists, industry, and natural-resource managers in predicting potential outcomes of noise exposure.

https://www.wildliferesearch.co.uk/Wildlife_Research/Publications_files/A%20synthesis%20of%20two%20decades%20of%20research%20documenting%20the%20effects%20of%20noise%20on%20wildlife%20Shannon.pdf

A synthesis of two decades of research documenting the effects of noise on wildlife

Rethinking sound detection by fishes.

There is growing evidence that the dynamics of biological systems that appear to be exponential over short time courses are in some cases better described over the long-term by power-law dynamics. A model of rate adaptation at the synapse between inner hair cells and auditory-nerve (AN) fibers that includes both exponential and power-law dynamics is presented here. Exponentially adapting components with rapid and short-term time constants, which are mainly responsible for shaping onset responses, are followed by two parallel paths with power-law adaptation that provide slowly and rapidly adapting responses. The slowly adapting power-law component significantly improves predictions of the recovery of the AN response after stimulus offset. The faster power-law adaptation is necessary to account for the “additivity” of rate in response to stimuli with amplitude increments. The proposed model is capable of accurately predicting several sets of AN data, including amplitude-modulation transfer functions, long-term adaptation, forward masking, and adaptation to increments and decrements in the amplitude of an ongoing stimulus.

/pdf/a-phenomenological-model-of-the-synapse-between-the-inner-2shf5p65sy.pdf

A phenomenological model of the synapse between the inner hair cell and auditory nerve: Long-term adaptation with power-law dynamics

Unpredicted human safety events in clinical trials for new drugs are costly in terms of human health and money. The drug discovery industry attempts to minimize those events with diligent preclinical safety testing. Current standard practices are good at preventing toxic compounds from being tested in the clinic; however, false negative preclinical toxicity results are still a reality. Continual improvement must be pursued in the preclinical realm. Higher-quality therapies can be brought forward with more information about potential toxicities and associated mechanisms. The zebrafish model is a bridge between in vitro assays and mammalian in vivo studies. This model is powerful in its breadth of application and tractability for research. In the past two decades, our understanding of disease biology and drug toxicity has grown significantly owing to thousands of studies on this tiny vertebrate. This Review summarizes challenges and strengths of the model, discusses the 3Rs value that it can deliver, highlights translatable and untranslatable biology, and brings together reports from recent studies with zebrafish focusing on new drug discovery toxicology.

Use of Zebrafish in Drug Discovery Toxicology

ASA S3/SC1.4 TR-2014 Sound Exposure Guidelines for Fishes and Sea Turtles: A Technical Report prepared by ANSI-Accredited Standards Committee S3/SC1 and registered with ANSI

Zebrafish (Danio rerio) have become a valuable model for investigating the molecular genetics and development of the inner ear in vertebrates. In this study, we employed a prepulse inhibition (PPI) paradigm to assess hearing in larval wild-type (AB) zebrafish during early development at 5-6 days post-fertilization (d.p.f.). We measured the PPI of the acoustic startle response in zebrafish using a 1-dimensional shaker that simulated the particle motion component of sound along the fish's dorsoventral axis. The thresholds to startle-inducing stimuli were determined in 5-6 d.p.f. zebrafish, and their hearing sensitivity was then characterized using the thresholds of prepulse tone stimuli (90-1200 Hz) that inhibited the acoustic startle response to a reliable startle stimulus (820 Hz at 20 dB re. 1 m s(-2)). Hearing thresholds were defined as the minimum prepulse tone level required to significantly reduce the startle response probability compared with the baseline (no-prepulse) condition. Larval zebrafish showed greatest auditory sensitivity from 90 to 310 Hz with corresponding mean thresholds of -19 to -10 dB re. 1 m s(-2), respectively. Hearing thresholds of prepulse tones were considerably lower than previously predicted by startle response assays. The PPI assay was also used to investigate the relative contribution of the lateral line to the detection of acoustic stimuli. After aminoglycoside-induced neuromast hair-cell ablation, we found no difference in PPI thresholds between treated and control fish. We propose that this PPI assay can be used to screen for novel zebrafish hearing mutants and to investigate the ontogeny of hearing in zebrafish and other fishes.

Auditory sensitivity of larval zebrafish ( Danio rerio ) measured using a behavioral prepulse inhibition assay

Sound-source localization behavior was studied in the plainfin midshipman fish (Porichthys notatus) by making use of the naturally occurring phonotaxis response of gravid females to playback of the male's advertisement call. The observations took place outdoors in a circular concrete tank. A dipole sound projector was placed at the center of the tank and an 80-90 Hz tone (the approximate fundamental frequency to the male's advertisement call) was broadcast to gravid females that were released from alternative sites approximately 100 cm from the source. The phonotaxic responses of females to the source were recorded, analyzed and compared with the sound field. One release site was approximately along the vibratory axis of the dipole source, and the other was approximately orthogonal to the vibratory axis. The sound field in the tank was fully characterized through measurements of the sound pressure field using hydrophones and acoustic particle motion using an accelerometer. These measurements confirmed that the sound field was a nearly ideal dipole. When released along the dipole vibratory axis, the responding female fish took essentially straight paths to the source. However, when released approximately 90 deg to the source's vibratory axis, the responding females took highly curved paths to the source that were approximately in line with the local particle motion axes. These results indicate that the acoustic cues used by fish during sound-source localization include the axes of particle motion of the local sound field.

/pdf/local-acoustic-particle-motion-guides-sound-source-2w14ykie33.pdf

Local acoustic particle motion guides sound-source localization behavior in the plainfin midshipman fish, Porichthys notatus.

Sound source localization of the midshipman fish (Porichthys notatus) was studied using the phonotactic response of gravid females to synthetic advertisement calls. Playback experiments were conducted in a 12‐ft‐diameter outdoor concrete tank at the Bodega Marine Laboratory using a J‐9 transducer placed at the center of the tank. The sound field in the tank was measured at 5‐cm intervals using an eight‐hydrophone array to measure the pressure gradients from which particle motion vectors were calculated. The acoustic measurements confirmed that the J‐9 projector was operating as a monopole source. Animals were released 90 cm away from the sound source, and 60 positive phonotactic responses from naive gravid females were video taped and analyzed. The phonotactic responses consisted primarily of straight to somewhat curved tracks to the sound source. Abrupt changes in trajectory to the sound source were rarely observed. The results confirm that fish can locate sound sources in the near field.

Sound source localization by the plainfin midshipman fish (Porichthys notatus).

Caged fish were exposed to sound from mid-frequency active (MFA) transducers in a 5 × 5 planar array which simulated MFA sounds at received sound pressure levels of 210 dB SPL(re 1 μPa). The exposure sound consisted of a 2 s frequency sweep from 2.8 to 3.8 kHz followed by a 1 s tone at 3.3 kHz. The sound sequence was repeated every 25 s for five repetitions resulting in a cumulative sound exposure level (SELcum) of 220 dB re 1 μPa2 s. The cumulative exposure level did not affect the hearing sensitivity of rainbow trout, a species whose hearing range is lower than the frequencies in the presented MFA sound. In contrast, one cohort of channel catfish showed a statistically significant temporary threshold shift of 4–6 dB at 2300 Hz, but not at lower tested frequencies, whereas a second cohort showed no change. It is likely that this threshold shift resulted from the frequency spectrum of the MFA sound overlapping with the upper end of the hearing frequency range of the channel catfish. The observed threshold shifts in channel catfish recovered within 24 h. There was no mortality associated with the MFA sound exposure used in this test.

David G. Zeddies

Papers

ASA S3/SC1.4 TR-2014 Sound Exposure Guidelines for Fishes and Sea Turtles: A Technical Report prepared by ANSI-Accredited Standards Committee S3/SC1 and registered with ANSI

Auditory sensitivity of larval zebrafish ( Danio rerio ) measured using a behavioral prepulse inhibition assay

Local acoustic particle motion guides sound-source localization behavior in the plainfin midshipman fish, Porichthys notatus.

Sound source localization by the plainfin midshipman fish (Porichthys notatus).

Effects of mid-frequency active sonar on hearing in fish.