Infrasound Sensitivity in the Plaice (Pleuronectes Platessa)

1992 ◽  
Vol 171 (1) ◽  
pp. 173-187 ◽  
Author(s):  
HANS ERIK KARLSEN
Keyword(s):  
Resonant Frequency ◽  
Test Chamber ◽  
Low Frequency ◽  
Harmonic Oscillators ◽  
Otolith Organs ◽  
Threshold Values ◽  
Frequency Range ◽  
Pleuronectes Platessa ◽  
Steel Wires ◽  
Cardiac Conditioning

The sensitivity of plaice (Pleuronectes platessa) to infrasound has been examined using a seawater-filled test chamber suspended by steel wires like a swing and driven by a vibrator. The sensitivity to low-frequency vibrations was determined using the cardiac conditioning technique. All plaice readily responded to infrasound down to 0.1 Hz, which was the lowest frequency tested, with threshold values of approximately 4×10−5 ms−2 rms. This sensitivity is comparable to infrasound thresholds found in other fish species and it agrees with the acceleration thresholds for plaice in the frequency range 30–100 Hz. The water movements relative to the fish surface produced during stimulation were below lateral-line thresholds. The inner ear otolith organs are thus probably responsible for the observed responses to infrasound. The hearing capabilities of plaice may be explained by these organs functioning as slightly underdamped harmonic oscillators with a resonant frequency close to 100Hz.

scholarly journals Detection of infrasound by the Atlantic cod

1986 ◽  
Vol 125 (1) ◽  
pp. 197-204 ◽  
Author(s):  
O. Sand ◽  
H. E. Karlsen
Keyword(s):  
Ambient Noise ◽  
Atlantic Cod ◽  
Low Frequency ◽  
Directional Pattern ◽  
Frequency Noise ◽  
Threshold Values ◽  
Sensory Inputs ◽  
A Value ◽  
Cardiac Conditioning ◽  
Lower Frequencies

Below about 50 kHz the level of ambient noise in the sea increases continuously towards lower frequencies. In the infrasound range the spectral slope is particularly steep. This low-frequency noise may propagate long distances with little attenuation, causing a directional pattern of infrasound in the sea. Using a standing-wave acoustic tube, we have studied the sensitivity of cod to infrasound down to 0.1 Hz by means of the cardiac conditioning technique. The threshold values, measured as particle acceleration, showed a steady decline towards lower frequencies below 10 Hz, reaching a value close to 10(−5)ms-2 at 0.1 Hz. The spectrum level at 0.1 Hz in the sea ranges between 120 and 180 dB (re 1 microPa), with corresponding particle accelerations from less than 10(−6) to more than 10(−4)ms-2. The sensitivity of cod is thus sufficient to detect the highest levels of ambient infrasound, and we put forward the hypothesis that fish may utilize information about the infrasound pattern in the sea for orientation during migration, probably in addition to an array of other sensory inputs.

scholarly journals The Inner Ear is Responsible for Detection of Infrasound in the Perch (Perca Fluviatilis)

1992 ◽  
Vol 171 (1) ◽  
pp. 163-172 ◽  
Author(s):  
HANSERIK KARLSEN
Keyword(s):  
Inner Ear ◽  
Lateral Line ◽  
Low Frequency ◽  
Perca Fluviatilis ◽  
Lateral Line System ◽  
Threshold Values ◽  
Line System ◽  
Frequency Detection ◽  
Perch Perca Fluviatilis ◽  
Cardiac Conditioning

In a previous study of infrasound detection in the cod, the inner ear was suggested to be the sensory organ responsible for the responses. However, a possible involvement of the lateral-line system in the observed low-frequency detection could not be ruled out. The infrasound sensitivity was therefore studied in perch (Perca fluviatilis) with normal and blocked lateral-line organs. The experiments were performed using a standing wave acoustic tube and the cardiac conditioning technique. All perch readily responded to infrasound frequencies down to 0.3 Hz with threshold values of approximately 2×10−4 ms−2. These thresholds were not affected by complete blocking of the lateral-line system with Co2+, which suggests that the inner ear is responsible for the observed infrasound detection by the perch.

scholarly journals Numerical investigation on low-frequency noise damping performances of Helmholtz resonators with an extended neck in presence of a grazing flow

2021 ◽  
pp. 146134842110205
Author(s):  
Weiwei Wu ◽  
Yiheng Guan
Keyword(s):  
Resonant Frequency ◽  
Stokes Equations ◽  
Transmission Loss ◽  
Low Frequency ◽  
Helmholtz Resonator ◽  
Frequency Noise ◽  
Frequency Range ◽  
Helmholtz Resonators ◽  
Numerical Predictions ◽  
Grazing Flow

In this work, modified designs of Helmholtz resonators with extended deflected neck are proposed, numerically evaluated and optimized aiming to achieve a better transmission loss performance over a broader frequency range. For this, 10 Helmholtz resonators with different extended neck configurations (e.g. the angle between extended neck and the y-axis) in the presence of a grazing flow are assessed. Comparison is then made between the proposed resonators and the conventional one, i.e. in the absence of an extended neck (i.e. Design A). For this, a two-dimensional linearized Navier Stokes equations-based model of a duct with the modified Helmholtz resonator implemented was developed in frequency domain. The model was first validated by comparing its numerical predictions with the experimental results available in the literature and the theoretical results. The model was then applied to evaluate the noise damping performance of the Helmholtz resonator with (1) an extended neck on the upstream side (Design B); (2) on the downstream side (Design C), (3) both upstream and downstream sides (Design D), (4) the angle between the extended neck and the y-axis, i.e. (a) 0°, (b) 30°, and (c) 45°, (d) 48.321°. In addition, the effects of the grazing flow Mach number (Ma) were evaluated. It was found that the transmission loss peaks of the Helmholtz resonator with the extended neck was maximized at Ma = 0.03 than at the other Mach numbers. Conventional resonator, i.e. Design A was observed to be associated with a lower transmission loss performance at a lower resonant frequency than those as observed on Designs B–D. Moreover, the optimum design of the proposed resonators with the extended neck is shown to be able to shift the resonant frequency by approximately 90 Hz, and maximum transmission loss could be increased by 28–30 dB. In addition, the resonators with extended necks are found to be associated with two or three transmission loss peaks, indicating that these designs have a broader effective frequency range. Finally, the neck deflection angles of 30° and 45° are shown to be involved with better transmission loss peaks than that with a deflection angle of 0°. In summary, the present study sheds light on maximizing the resonator’s noise damping performances by applying and optimizing an extended neck.

scholarly journals Control the Frequency Response of a Loudspeaker by Changing Its Enclosure

2021 ◽  
Vol 4 (2) ◽  
Author(s):  
Pavlo Olehovych Riabokon
Keyword(s):  
Resonant Frequency ◽  
Resonance Frequency ◽  
Frequency Response ◽  
Rock Music ◽  
Low Frequency ◽  
Total Quality ◽  
Frequency Range ◽  
Low Frequencies ◽  
Frequency Components ◽  
Internal Volume

This article analyzes how to control frequency response of a loudspeaker by changing the volume of its closed-box enclosure. The calculation is performed by the method of  Thiele-Small on the basic of a pre-calculated loudspeaker, the parameters of which are given in third section. This became possible because of the simplification of the circuit on figure 1 to the form of circuit on figure 2. This allowed us to consider it as a second order filter (presence of two reactive elements). Obtained results are compared with corresponding characteristics of open-box enclosure of the same loudspeaker, that was pre-calculated by the author too. Results are presented graphically in figure 3 and 4. As can be seen from them, the resonant frequency of the loudspeaker in the closed-box enclosure is higher than the resonant frequency of the loudspeaker in the open box. The result in the form of a ratio  is listed in table 2. Analyzing the obtained data, it can be noticed that with the change of the internal volume of the closed box (and hence its total quality factor), it is possible to affect both the resonance frequency and the peak amplitude values in these frequencies by changing the FR. The result shown in figure 3 and 4 is achieved by taking into account effect of radiation only on the one side of the driver (in the case of open-box enclosure). Closed box was calculating by taking into account both sides radiation of the driver. Shifting the resonance frequency of the system towards higher frequencies and increasing the sound pressure on the resonance generally worsens the FR of the loudspeaker (reduces the reproduction of low-frequency components of sound and increases the unevenness of the frequency). However, certain variants of this group of frequency characteristics may be useful depending on the reproducible frequency range and need of emphasize the low-frequency components (for example, in rock music). If you need a smoothed low-frequency sound, it is appropriate to use systems with low overall quality and increased internal volume or open-box enclosure. Therefore, the volume of the closed-box enclosure significantly affects the resonant frequency and the shape of the frequency response of the loudspeaker. Reducing the volume of the enclosure of the loudspeaker leads to a decrease in its frequency range due to low frequencies and at the same time increase in the unevenness of the frequency response. The change in the resonant frequency of the system as the volume of the closed-box enclosure decreases, the less the volume of the closed-box.

Otolith Deprivation Induces Optokinetic Compensation

2005 ◽  
Vol 94 (5) ◽  
pp. 3487-3496 ◽  
Author(s):  
Corina E. Andreescu ◽  
Martijn M. De Ruiter ◽  
Chris I. De Zeeuw ◽  
Marcel T. G. De Jeu
Keyword(s):  
Eye Movements ◽  
Multisensory Integration ◽  
Stimulus Frequency ◽  
Low Frequency ◽  
Integration Theory ◽  
Otolith Organs ◽  
Frequency Range ◽  
Optokinetic Reflex ◽  
Proprioceptive Inputs ◽  
Model Support

According to the multisensory integration theory vestibular, optokinetic and proprioceptive inputs act in concert to maintain a stable retinal image of the visual world. Yet, it remains elusive to what extent the otolith organs contribute to this process and whether a specific loss of otolith input is compensated for. Here we investigated the compensatory eye movements in tilted mice, which lack otoconia because of a mutation in otopetrin 1. Tilted mice showed very small displacements of the eyes in the orbit during static roll paradigms, suggesting the absence of functional otolith organs. Independent of head position with respect to gravity, the gain and phase lead of angular vestibuloocular reflex of tilted mice were decreased and increased, respectively (frequencies 0.2 to 1 Hz and peak accelerations 8 to 197°/s2, respectively). Furthermore, lack of otolith input increases the dependency of the vestibular system on stimulus frequency. In contrast, the gain of optokinetic reflex in tilted mice was significantly higher in the low-frequency range than in control mice, regardless of the position of the mice in space or the plane of the eye movements. To explain these results, a simple model was used in which a multisensory integration unit was embedded. With this model, we were able to simulate all the behaviors observed. Thus our data and the model support the presence of the multisensory integration system and revealed a compensatory enhanced optokinetic reflex in tilted mice, indicating an adaptive synergism in the processing of otolith and visually driven signals.

Evaluation of Special Hearing Aids for Deaf Children

1971 ◽  
Vol 36 (4) ◽  
pp. 527-537 ◽  
Author(s):  
Norman P. Erber
Keyword(s):  
Hearing Aids ◽  
High Frequency ◽  
Hearing Aid ◽  
Low Frequency ◽  
Acoustic Stimulation ◽  
Deaf Children ◽  
Frequency Range ◽  
Frequency Limit ◽  
Unpublished Studies ◽  
Published Research

Two types of special hearing aid have been developed recently to improve the reception of speech by profoundly deaf children. In a different way, each special system provides greater low-frequency acoustic stimulation to deaf ears than does a conventional hearing aid. One of the devices extends the low-frequency limit of amplification; the other shifts high-frequency energy to a lower frequency range. In general, previous evaluations of these special hearing aids have obtained inconsistent or inconclusive results. This paper reviews most of the published research on the use of special hearing aids by deaf children, summarizes several unpublished studies, and suggests a set of guidelines for future evaluations of special and conventional amplification systems.

Dynamic Damping and Stiffness Characteristics of the Rolling Tire

2001 ◽  
Vol 29 (4) ◽  
pp. 258-268 ◽  
Author(s):  
G. Jianmin ◽  
R. Gall ◽  
W. Zuomin
Keyword(s):  
Dynamic Behavior ◽  
Variable Parameter ◽  
Low Frequency ◽  
Vertical Load ◽  
Frequency Range ◽  
Inflation Pressure ◽  
Vehicle Simulation ◽  
Dynamic Damping ◽  
Speed Range ◽  
Stiffness Characteristics

Abstract A variable parameter model to study dynamic tire responses is presented. A modified device to measure terrain roughness is used to measure dynamic damping and stiffness characteristics of rolling tires. The device was used to examine the dynamic behavior of a tire in the speed range from 0 to 10 km/h. The inflation pressure during the tests was adjusted to 160, 240, and 320 kPa. The vertical load was 5.2 kN. The results indicate that the damping and stiffness decrease with velocity. Regression formulas for the non-linear experimental damping and stiffness are obtained. These results can be used as input parameters for vehicle simulation to evaluate the vehicle's driving and comfort performance in the medium-low frequency range (0–100 Hz). This way it can be important for tire design and the forecasting of the dynamic behavior of tires.

scholarly journals An Improved Time Integration Method Based on Galerkin Weak Form with Controllable Numerical Dissipation

2021 ◽  
Vol 11 (4) ◽  
pp. 1932
Author(s):  
Weixuan Wang ◽  
Qinyan Xing ◽  
Qinghao Yang
Keyword(s):  
High Frequency ◽  
Integration Method ◽  
Time Integration ◽  
Low Frequency ◽  
Weak Form ◽  
High Accuracy ◽  
Numerical Dissipation ◽  
Frequency Range ◽  
Time Integration Method ◽  
Numerical Damping

Based on the newly proposed generalized Galerkin weak form (GGW) method, a two-step time integration method with controllable numerical dissipation is presented. In the first sub-step, the GGW method is used, and in the second sub-step, a new parameter is introduced by using the idea of a trapezoidal integral. According to the numerical analysis, it can be concluded that this method is unconditionally stable and its numerical damping is controllable with the change in introduced parameters. Compared with the GGW method, this two-step scheme avoids the fast numerical dissipation in a low-frequency range. To highlight the performance of the proposed method, some numerical problems are presented and illustrated which show that this method possesses superior accuracy, stability and efficiency compared with conventional trapezoidal rule, the Wilson method, and the Bathe method. High accuracy in a low-frequency range and controllable numerical dissipation in a high-frequency range are both the merits of the method.

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