scholarly journals Decision making in the face of a deadly predator: high-amplitude behavioural thresholds can be adaptive for rainforest crickets under high background noise levels

2020 ◽  
Vol 375 (1802) ◽  
pp. 20190471 ◽  
Author(s):  
Heiner Römer ◽  
Marc Holderied
Keyword(s):  
Background Noise ◽  
Experimental Tests ◽  
High Amplitude ◽  
Decision Criterion ◽  
Target Strength ◽  
False Alarms ◽  
Noise Levels ◽  
High Background ◽  
Ultrasonic Calls ◽  
High Background Noise

Many insect families have evolved ears that are adapted to detect ultrasonic calls of bats. The acoustic sensory cues indicating the presence of a bat are then used to initiate bat avoidance behaviours. Background noise, in particular at ultrasonic frequencies, complicates these decisions, since a response to the background may result in costly false alarms. Here, we quantify bat avoidance responses of small rainforest crickets (Gryllidae, Trigoniinae), which live under conditions of high levels of ultrasonic background noise. Their bat avoidance behaviour exhibits markedly higher thresholds than most other studied eared insects. Their responses do not qualitatively differ at suprathreshold amplitudes up to sound pressure levels of 105 dB. Moreover, they also exhibit evasive responses to single, high-frequency events and do not require the repetitive sequence of ultrasonic calls typical for the search phase of bat echolocation calls. Analysis of bat and katydid sound amplitudes and peak frequencies in the crickets' rainforest habitat revealed that the cricket's behavioural threshold would successfully reject the katydid background noise. Using measurements of the crickets' echo target strength for bat predators, we calculated the detection distances for both predators and prey. Despite their high behavioural threshold, the cricket prey still has a significant detection advantage at frequencies between 20 and 40 kHz. The low-amplitude bat calls they ignore are no predation threat because even much louder calls would be detected before the bat would hear the cricket echo. This leaves ample time for evasive actions. Thus, a simple decision criterion based on a high-amplitude behavioural threshold can be adaptive under the high background noise levels in nocturnal rainforests, in avoiding false alarms and only missing detection for bat calls too far away to pose a risk. This article is part of the theme issue ‘Signal detection theory in recognition systems: from evolving models to experimental tests’.

Effects of Classroom Noise on Students and Teachers in Greece

2003 ◽  
Vol 96 (2) ◽  
pp. 539-544 ◽  
Author(s):  
Dimitris Skarlatos ◽  
Manolis Manatakis
Keyword(s):  
High School ◽  
Background Noise ◽  
Reverberation Time ◽  
Noise Levels ◽  
High Background ◽  
High Noise ◽  
Significant Percentage ◽  
Time Period ◽  
High Background Noise

Measurements inside 32 occupied high-school classrooms during the courses showed that the measured long-term equivalent noise levels are high. A significant percentage of students and teachers found these levels unacceptable. The observed noise levels depend on the time period of the course, the age, and the number of the students in each classroom. The large reverberation time and the high background noise are responsible for the measured high noise level.

scholarly journals Separating overlapping echolocation: An updated method for estimating the number of echolocating animals in high background noise levels

2021 ◽  
Vol 150 (2) ◽  
pp. 709-717
Author(s):  
Rebecca A. Hamilton ◽  
Josefin Starkhammar ◽  
Stefanie K. Gazda ◽  
Richard C. Connor
Keyword(s):  
Background Noise ◽  
Noise Levels ◽  
High Background ◽  
High Background Noise

scholarly journals Multiple signals and male spacing affect female preference at cocktail parties in treefrogs

2009 ◽  
Vol 277 (1685) ◽  
pp. 1247-1252 ◽  
Author(s):  
Christina Richardson ◽  
Thierry Lengagne
Keyword(s):  
Background Noise ◽  
Spatial Separation ◽  
Signal Design ◽  
High Background ◽  
Hyla Arborea ◽  
Male Density ◽  
Multicomponent Signals ◽  
The Face ◽  
Spatial Unmasking ◽  
High Background Noise

Effective acoustic communication in the face of intense conspecific background noise constitutes a constant sensory challenge in chorusing and colonial species. An evolutionary approach suggests that behavioural and environmental constraints in these species should have shaped signal design and signalling behaviour to enable communication in noisy conditions. This could be attained both through the use of multicomponent signals and through short-term adjustments in the spatial separation of calling males. We investigated these two hypotheses in a chorusing anuran, the hylid Hyla arborea , through a series of phonotaxis experiments conducted within a six-speaker arena in a high background noise situation, by presenting females with male calls containing either single or multiple attractive call components, and by modifying distances between speakers. We found that female ability to discriminate attractive calls increased when several attractive call components were available, providing novel evidence that the use of multicomponent signals enhances communication in complex acoustic conditions. Signal discrimination in females also improved with speaker separation, demonstrating that within natural choruses, spatial unmasking conditioned by male density and spatial separation probably improves female discrimination of competing males. Implications of these results for the accuracy of mate choice within choruses are discussed.

scholarly journals A technical description of the Balloon Lidar Experiment (BOLIDE)

2020 ◽  
Vol 13 (10) ◽  
pp. 5681-5695
Author(s):  
Bernd Kaifler ◽  
Dimitry Rempel ◽  
Philipp Roßi ◽  
Christian Büdenbender ◽  
Natalie Kaifler ◽  
...  
Keyword(s):  
High Resolution ◽  
Time Resolution ◽  
Background Noise ◽  
Flight Performance ◽  
Vertical Resolution ◽  
Backscatter Coefficient ◽  
High Background ◽  
Polar Mesospheric Clouds ◽  
High Background Noise ◽  
Mesospheric Clouds

Abstract. The Balloon Lidar Experiment (BOLIDE) was the first high-power lidar flown and operated successfully on board a balloon platform. As part of the PMC Turbo payload, the instrument acquired high-resolution backscatter profiles of polar mesospheric clouds (PMCs) from an altitude of ∼ 38 km during its maiden ∼ 6 d flight from Esrange, Sweden, to northern Canada in July 2018. We describe the BOLIDE instrument and its development and report on the predicted and actual in-flight performance. Although the instrument suffered from excessively high background noise, we were able to detect PMCs with a volume backscatter coefficient as low as 0.6×10-10 m−1 sr−1 at a vertical resolution of 100 m and a time resolution of 30 s.

A Seismic Refraction Profile Across the Polar Continental Shelf of the Queen Elizabeth Islands

1971 ◽  
Vol 8 (3) ◽  
pp. 347-360 ◽  
Author(s):  
M. J. Berry ◽  
K. G. Barr
Keyword(s):  
Continental Slope ◽  
Broad Band ◽  
Seismic Refraction ◽  
Low Frequency ◽  
Water Layer ◽  
Noise Levels ◽  
High Background ◽  
Crustal Model ◽  
Seismic Recording ◽  
High Background Noise

During the spring of 1967, a seismic refraction experiment was conducted from the SW tip of Prince Patrick Island in the Queen Elizabeth Islands of Arctic Canada to a point mid-way down the continental slope, some 220 km from the coast.It was found that seismic recording on sea ice was plagued by unusually high background noise levels which could be attributed to low frequency (below 1 Hz) oscillations of the ice pans and to the broad-band noise generated by frequent ice cracking. It was discovered, and is shown theoretically, that seismic wave propagating through a water layer (the ocean) and incident on the ice layer from below provide an exact π/2 phase shift between the horizontal and vertical components of surface motion. This fact can be used to advantage in digital processing.The interpretation shows a crustal model with depths to the M discontinuity of 28 ± 4 km at the coast, thinning to 15 ± 9 km at the end of the profile. The velocity of the mantle is measured as 8.05 ± 0.17 km/s. Mid-way down the continental slope there are 5.0 ± 1.63 km of sediments overlying material with a velocity of 5.36 ± 0.15 km/s. Material of a similar velocity, 5.72 ± 0.18 km/s, lies 2.7 ± 1.9 km beneath the surface material at the coast, where the surface layer has a velocity of 4.76 ± 0.4 km/s. It is concluded that the data support the hypothesis that the Canada Basin has an oceanic rather than a continental crust.

Improved affine projection subband adaptive filter for high background noise environments

2017 ◽  
Vol 137 ◽  
pp. 356-362 ◽  
Author(s):  
Haiquan Zhao ◽  
Zongsheng Zheng ◽  
Zhongyu Wang ◽  
Badong Chen
Keyword(s):  
Adaptive Filter ◽  
Background Noise ◽  
High Background ◽  
Affine Projection ◽  
High Background Noise ◽  
Subband Adaptive Filter

scholarly journals A technical description of the Balloon Lidar Experiment BOLIDE

2020 ◽  
Author(s):  
Bernd Kaifler ◽  
Dimitry Rempel ◽  
Philipp Roßi ◽  
Christian Büdenbender ◽  
Natalie Kaifler ◽  
...  
Keyword(s):  
High Resolution ◽  
Time Resolution ◽  
Background Noise ◽  
Flight Performance ◽  
Vertical Resolution ◽  
Backscatter Coefficient ◽  
High Background ◽  
Polar Mesospheric Clouds ◽  
High Background Noise ◽  
Mesospheric Clouds

Abstract. The Balloon Lidar Experiment (BOLIDE) was the first high-power lidar flown and operated successfully onboard a balloon platform. As part of the PMC Turbo payload, the instrument acquired high resolution backscatter profiles of Polar Mesospheric Clouds (PMCs) from an altitude of ∼38 km during its maiden ∼6 day flight from Esrange, Sweden, to Northern Canada in July 2018. We describe the BOLIDE instrument and its development and report on the predicted and actual in-flight performance. Although the instrument suffered from excessively high background noise, we were able to detect PMCs with a volume backscatter coefficient as low as 0.6 × 10−10 m−1 sr−1 at a vertical resolution of 100 m and a time resolution of 30 s.

scholarly journals An Entropy-Based Anti-Noise Method for Reducing Ranging Error in Photon Counting Lidar

Entropy ◽  
2021 ◽  
Vol 23 (11) ◽  
pp. 1499
Author(s):  
Mingwei Huang ◽  
Zijing Zhang ◽  
Jiaheng Xie ◽  
Jiahuan Li ◽  
Yuan Zhao
Keyword(s):  
Background Noise ◽  
Photon Counting ◽  
Laser Pulses ◽  
Avalanche Photodiode ◽  
High Background ◽  
Noise Current ◽  
Ranging Error ◽  
Geiger Mode ◽  
High Background Noise ◽  
The Difference

Photon counting lidar for long-range detection faces the problem of declining ranging performance caused by background noise. Current anti-noise methods are not robust enough in the case of weak signal and strong background noise, resulting in poor ranging error. In this work, based on the characteristics of the uncertainty of echo signal and noise in photon counting lidar, an entropy-based anti-noise method is proposed to reduce the ranging error under high background noise. Firstly, the photon counting entropy, which is considered as the feature to distinguish signal from noise, is defined to quantify the uncertainty of fluctuation among photon events responding to the Geiger mode avalanche photodiode. Then, the photon counting entropy is combined with a windowing operation to enhance the difference between signal and noise, so as to mitigate the effect of background noise and estimate the time of flight of the laser pulses. Simulation and experimental analysis show that the proposed method improves the anti-noise performance well, and experimental results demonstrate that the proposed method effectively mitigates the effect of background noise to reduce ranging error despite high background noise.

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