scholarly journals Directional hearing in insects: biophysical, physiological and ecological challenges

2020 ◽  
Vol 223 (14) ◽  
pp. jeb203224
Author(s):  
Heiner Römer
Keyword(s):  
Vertical Plane ◽  
Sound Field ◽  
External World ◽  
Directional Hearing ◽  
Sound Localisation ◽  
System A ◽  
Integrative View ◽  
Vector Quantity ◽  
Body Sizes ◽  
Adaptive Behaviours

ABSTRACTSound localisation is a fundamental attribute of the way that animals perceive their external world. It enables them to locate mates or prey, determine the direction from which a predator is approaching and initiate adaptive behaviours. Evidence from different biological disciplines that has accumulated over the last two decades indicates how small insects with body sizes much smaller than the wavelength of the sound of interest achieve a localisation performance that is similar to that of mammals. This Review starts by describing the distinction between tympanal ears (as in grasshoppers, crickets, cicadas, moths or mantids) and flagellar ears (specifically antennae in mosquitoes and fruit flies). The challenges faced by insects when receiving directional cues differ depending on whether they have tympanal or flagellar years, because the latter respond to the particle velocity component (a vector quantity) of the sound field, whereas the former respond to the pressure component (a scalar quantity). Insects have evolved sophisticated biophysical solutions to meet these challenges, which provide binaural cues for directional hearing. The physiological challenge is to reliably encode these cues in the neuronal activity of the afferent auditory system, a non-trivial problem in particular for those insect systems composed of only few nerve cells which exhibit a considerable amount of intrinsic and extrinsic response variability. To provide an integrative view of directional hearing, I complement the description of these biophysical and physiological solutions by presenting findings on localisation in real-world situations, including evidence for localisation in the vertical plane.

scholarly journals Neurophysiology goes wild: from exploring sensory coding in sound proof rooms to natural environments

2021 ◽  
Vol 207 (3) ◽  
pp. 303-319
Author(s):  
Heiner Römer
Keyword(s):  
Sensory System ◽  
Sensory Systems ◽  
Natural Environments ◽  
Sensory Coding ◽  
Noise Levels ◽  
Sensory Physiology ◽  
Sound Localisation ◽  
Physical Environments ◽  
History Of ◽  
Adaptive Behaviours

AbstractTo perform adaptive behaviours, animals have to establish a representation of the physical “outside” world. How these representations are created by sensory systems is a central issue in sensory physiology. This review addresses the history of experimental approaches toward ideas about sensory coding, using the relatively simple auditory system of acoustic insects. I will discuss the empirical evidence in support of Barlow’s “efficient coding hypothesis”, which argues that the coding properties of neurons undergo specific adaptations that allow insects to detect biologically important acoustic stimuli. This hypothesis opposes the view that the sensory systems of receivers are biased as a result of their phylogeny, which finally determine whether a sound stimulus elicits a behavioural response. Acoustic signals are often transmitted over considerable distances in complex physical environments with high noise levels, resulting in degradation of the temporal pattern of stimuli, unpredictable attenuation, reduced signal-to-noise levels, and degradation of cues used for sound localisation. Thus, a more naturalistic view of sensory coding must be taken, since the signals as broadcast by signallers are rarely equivalent to the effective stimuli encoded by the sensory system of receivers. The consequences of the environmental conditions for sensory coding are discussed.

Condense, Authorize, Destabilize: Multiperspectivism and Stratigraphy

2019 ◽  
Vol 29 (5) ◽  
pp. 7-32
Keyword(s):  
Theoretical Foundation ◽  
External World ◽  
Conceptual System ◽  
Philosophical Theory ◽  
Possible World ◽  
System A ◽  
Ability To Act ◽  
History Of ◽  
The Right ◽  
Dark Ecology

The paper is both an exercise in multiperspectivist analysis of metaphors and an attempt to find a theoretical foundation for the possibility of such a procedure. The concept of speculative realist “decentered thought,” which is most clearly encapsultated in Morton’s dark ecology project, implicitly presupposes a thematization and problematization of the “center” of the conceptual system - a mesh that makes the order reproduced by it a solid and stable picture of a possible world. Appealing to the theory of metaphor allows one to fix on this tension, which arises not between philosophical theory and some “external world” but between the conceptual system and the possible existence of way of ordering its instances. This also solves two problems: first, via reconfiguration of the concept of the “center” of the conceptual system by inscribing a metaphor into it; and second, by invoking and reinterpreting the Ankersmit problem to endow metaphor with the ability to act while highlighting the basic modes of its agency. This interpretation diverges from the classical - perspectivist - conceptualization of metaphor as an operator of unambiguous order in a theory and turns the systems of concepts themselves into clots of multiple and ambiguous interpretations of metaphors that always reserve the right to be something else and not the same as before. The article tests and illustrates this multiperspectivism with the conflict of metaphors involved in the transfer of the concept of Ian Bogost’s alien phenomenology to Levi Bryant’s onto-cartography system. The final part of the article elaborates a multiperspectivist stratigraphy project (an as yet non-existent branch of theory that would turn a metaphor into both an object and instrument of description and explanation) and also maps out points of uncertainty that, once overcome and clarified, would make such a stratigraphy possible. Why does the Other defeat Technology? Where has perspectivism failed? How is a history of metaphors possible if temporal regimes themselves turn out to be an effect of metaphorical operations? How can metaphors act? The article clarifies and details some answers to these and other questions.

Directional hearing of a grasshopper in the field

2000 ◽  
Vol 203 (6) ◽  
pp. 983-993 ◽  
Author(s):  
F. Gilbert ◽  
N. Elsner
Keyword(s):  
Sound Field ◽  
Contralateral Side ◽  
Directional Hearing ◽  
Natural Habitats ◽  
Nerve Activity ◽  
Sparse Vegetation ◽  
Dense Vegetation ◽  
Field Situation ◽  
Chorthippus Biguttulus ◽  
Similar Accuracy

An electrophysiological method for making long-term recordings from the tympanal nerve was developed in Chorthippus biguttulus (Gomphocerinae) to gain insight into the ecophysiological constraints of sound localization in acridid grasshoppers. Using this ‘biological microphone’, the directional dependence of auditory nerve activity was monitored both in the laboratory and in various natural habitats of this species. On gravel and in sparse vegetation, the overall patterns of directionality were found to be very similar to those in the free sound field in the laboratory, regardless of whether the animal was positioned horizontally or vertically. However, the differences between the ipsi- and contralateral sides were smaller in these habitats than in the laboratory. In dense vegetation, the directional patterns were greatly affected by the environment. Moreover, a minimum in nerve activity was not always reached on the contralateral side, as is typical for the free sound field situation. On the basis of these data, predictions can be made about the ability of the animals to determine the correct side of a sound source. In the free sound field of the laboratory, correct lateralizations are expected at all angles of sound incidence between 20 and 160 degrees, a prediction corresponding to the results of behavioural studies. In sparse vegetation, a similar accuracy can be anticipated, whereas on gravel and in dense vegetation directional hearing is expected to be severely degraded, especially if the animal is oriented horizontally. The predictions from our present electrophysiological investigations must now be confirmed by behavioural studies in the field.

The Auditory Behaviour of Flying Locusts

1989 ◽  
Vol 147 (1) ◽  
pp. 279-301 ◽  
Author(s):  
DANIEL ROBERT
Keyword(s):  
Avoidance Response ◽  
Locusta Migratoria ◽  
Biological Significance ◽  
Sound Field ◽  
Warning System ◽  
Frequency Component ◽  
Avoidance Behaviour ◽  
Directional Hearing ◽  
Wingbeat Frequency ◽  
Auditory Physiology

The auditory behaviour of tethered locusts flying in a wind tunnel was investigated under controlled acoustic conditions. 1. Reflection, attenuation and diffraction of ultrasound evoked by the locust's physical presence caused pronounced distortions of the acoustic field. Interaural pressure variations were observed that account for directional hearing at high frequencies. 2. Sound field measurements indicated only a minor influence of flight posture or wing position on the interaural pressure gradient. 3. The locusts steered away from pulsed ultrasounds that simulated bat echolocation signals. The phonotactic response was measured as ruddering by the abdomen and hind legs, resulting in a yaw torque directed away from the sound source. Wingbeat frequency increased by 15% in response to ultrasonic stimulation. This behaviour is considered to be analogous to the bat avoidance behaviour of flying crickets. 4. The avoidance response was observed for carrier frequencies higher than 10 kHz and for sound pressure levels (on average) higher than 45 dB SPL. Lowfrequency stimuli (<10kHz) failed to elicit any phonotactic steering at any intensity used (up to 100dB SPL). Because of its relatively low threshold of reaction, this steering behaviour is thought to be part of an early-warning system adapted to the acoustic detection of echolocating predators. 5. The avoidance response was suppressed when a 30 kHz (normally effective) tone was combined with a 5 kHz tone (which is ineffective alone). Two-tone suppression only occurred when the low-frequency component was 10–15 dB SPL higher than the high-frequency tone. The biological significance of two-tone suppression is discussed. 6. The intensity-response characteristics, the frequency sensitivity and the twotone suppression of the avoidance behaviour are discussed with respect to the auditory physiology of Locusta migratoria. The involvement of some identified auditory ascending interneurones in the avoidance behaviour is considered.

On-Line Identification and Location of Rotor Cracks

1993 ◽  
Author(s):  
Santosh Ratan ◽  
Haim Baruh ◽  
Jorge Rodriguez
Keyword(s):  
Sensitivity Analysis ◽  
Finite Element ◽  
Rotor System ◽  
Finite Element Discretization ◽  
Element Discretization ◽  
System A ◽  
Line Identification ◽  
Small Depth ◽  
Vector Quantity ◽  
On Line

Abstract A new method is proposed to detect and locate a crack in a rotor system. A vector quantity ‘Residue’ is defined using the measured vibration response of the rotor system and the modeled system matrices. It is shown that the non-zero elements of ‘Residue’ correspond to the nodes encompassing the element carrying the crack. Although, the derivation of ‘Residue’ is based on the linear model of the rotor system, the response due to the non-linearity caused by the breathing of the crack causes only a small amount of contamination. To investigate the robustness of the proposed method, a sensitivity analysis is conducted. It is found that the method could detect a crack of as small depth as 4% of the shaft diameter. The effects of light damping and the order of finite element discretization on the detection result are also investigated, and are found to be small.

Thermodynamics of Vlasov equilibria

1992 ◽  
Vol 48 (2) ◽  
pp. 281-307 ◽  
Author(s):  
E. Minardi
Keyword(s):  
External World ◽  
Thermodynamic Quantities ◽  
Particle Structure ◽  
Magnetic Systems ◽  
System A ◽  
Energy Interaction ◽  
Collective Plasma ◽  
Classical Thermodynamics ◽  
Systematic Exposition

This paper contains a systematic exposition of a statistical method leading to a characterization of relevant equilibrium and stability properties of col-lisionless Vlasov (collective) plasma configurations according to a formalism similar to that of the classical thermodynamics of Maxwellian systems. We reconsider a statistical model, proposed in earlier works, in which the basic objects of the statistics are volume elements in a configuration space of the charge or current density. The probability distribution in this space is calculated subject to a constraint expressing the existence of static equilibria involving only the smeared-out or collective part of the above densities, while the collective energy is uncorrelated with the fluctuations arising from the single-particle structure. It is one of the aims of this paper to show that the thermodynamic quantities arising automatically in the formalism, for instance the entropy, can be consistently inserted in the physical and conceptual context of classical thermodynamics. This is achieved by studying in detail a reversible energy interaction between the collective system and the external world, in order to identify the entropy variations calculated with the model with those of the entropy as conventionally defined. Our thermodynamic concepts are illustrated by applications to electrostatic Vlasov equilibria (in unstable situations and in the Maxwellian limit) and to magnetic systems, both in a case open to energy interaction with the external world (the tokamak) and in the case of an isolated system (a plasma enclosed in a perfectly conducting shell).

Tympanal hearing in the sarcophagid parasitoid fly Emblemasoma sp.: the biomechanics of directional hearing

1999 ◽  
Vol 202 (14) ◽  
pp. 1865-1876 ◽  
Author(s):  
D. Robert ◽  
R.N. Miles ◽  
R.R. Hoy
Keyword(s):  
Mechanical Response ◽  
Sound Field ◽  
Striking Difference ◽  
Directional Hearing ◽  
Vibrational Modes ◽  
Acoustic Detection ◽  
Sense Organs ◽  
Auditory Systems ◽  
Detection And Localization

In Diptera, tympanal hearing has evolved at least twice in flies that belong to two different families, the tachinids and the sarcophagids. Common to these flies is their parasitoid reproductive strategy, both relying on the acoustic detection and localization of their hosts, singing insects, by means of tympanal hearing organs. In the present study, the external anatomy of the unusual hearing organs of the sarcophagid fly Emblemasoma sp. is described. The sarcophagid ears bear numerous anatomical similarities with those of ormiine tachinids: they are located on the ventral prosternum and possess a pair of scolopidial mechanoreceptive sense organs. A striking difference, however, resides in the lack of a well-defined presternum in the sarcophagid tympanal system. Instead, a deep longitudinal fold, the tympanal fold, spans both hemilateral tympanal membranes across the midline of the animal. Measured using laser Doppler vibrometry, the tympanal mechanical response in the sound field reveals asymmetrical deflection shapes that differ from those of tachinids. Lacking a central fulcrum, the sarcophagid tympanal complex presents different vibrational modes that also result in interaural coupling. The evolutionarily convergent, yet distinct, solutions used by these two small auditory systems to extract directional cues from the sound field and the role of tympanal coupling in this process are discussed.

Zur Brownschen Bewegung schwerer, mäßig ausgedehnter Teilchen in einem verdünnten Gas

1969 ◽  
Vol 24 (10) ◽  
pp. 1575-1580
Author(s):  
Wolfgang Maass
Keyword(s):  
Distribution Function ◽  
Hard Spheres ◽  
Equations Of Motion ◽  
Sound Field ◽  
Coupled System ◽  
Bgk Model ◽  
System A ◽  
Dilute Gas ◽  
Brownian Particles ◽  
Phenomenological Coefficients

Abstract Starting from a master equation for a physical system consisting of mutually non-interacting Brownian particles in a dilute gas and using the collision model of hard spheres we obtain a coupled system of equations of motion for the Brownian distribution function F (R,V; t) and the (single-particle) distribution function f(r,v;t) of the gas. For these equations, assumed to form a "dynamical system", a "H-Theorem" yields asymptotic Lyapunov stability in the large relative to total (Maxwell) equilibrium ("tendency to equilibrium"). For example we investigate approximately the system influenced initially by a sound field (phenomenological coefficients of the equation for F, Fokker-Planck approximation, BGK model for the f-equation).

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