Constant-frequency and frequency-modulated components in the echolocation calls of three species of small bats (Emballonuridae, Thyropteridae, and Vespertilionidae)

1999 ◽  
Vol 77 (12) ◽  
pp. 1891-1900 ◽  
Author(s):  
M B Fenton ◽  
J Rydell ◽  
M J Vonhof ◽  
J Eklöf ◽  
W C Lancaster
Keyword(s):  
Single Frequency ◽  
Constant Frequency ◽  
Field Station ◽  
Echolocation Calls ◽  
Low Intensity ◽  
Low Duty Cycle ◽  
Frequency Components ◽  
Ca 50 ◽  
Higher Harmonic ◽  
Thyroptera Tricolor

The echolocation calls of Rhychonycteris naso (Emballonuridae), Thyroptera tricolor (Thyropteridae), and Myotis riparius (Vespertilionidae) were recorded at the Cãno Palma Field Station in Costa Rica in February 1998. All three species produced echolocation calls at low duty cycle (signal on ~10% of the time). While T. tricolor produced low-intensity echolocation calls that were barely detectable when the bats were <0.5 m from the microphone, the other two species produced high-intensity calls, readily detectable at distances >5 m. Myotis riparius produced calls that swept from about 120 kHz to just over 50 kHz in about 2 ms. We found no evidence of harmonics in these calls. Rhynchonycteris naso and T. tricolor produced multiharmonic echolocation calls. In R. naso the calls included narrowband and broadband components and varied in bandwidth, sweeping from just under 100 kHz to around 75 kHz in over 5 ms. Most calls were dominated by the higher harmonic (ca. 100 kHz), but some also included a lower one (ca. 50 kHz). The calls of T. tricolor were 5-10 ms long and dominated by a single frequency (ca. 45 kHz), sometimes with a ca. 25 kHz component. The echolocation calls of all three species included frequency-modulated and constant-frequency components. While these terms describe the components of the echolocation calls, they do not necessarily describe the bats' echolocation behaviour.

scholarly journals Echolocating bats exhibit differential amplitude compensation for noise interference at a sub-call level

2020 ◽  
Vol 223 (19) ◽  
pp. jeb225284
Author(s):  
Manman Lu ◽  
Guimin Zhang ◽  
Jinhong Luo
Keyword(s):  
Functional Role ◽  
Ambient Noise ◽  
Production Control ◽  
Constant Frequency ◽  
Vocal Production ◽  
Lombard Effect ◽  
Echolocation Calls ◽  
Noise Interference ◽  
Sound Communication ◽  
Amplitude Compensation

ABSTRACTFlexible vocal production control enables sound communication in both favorable and unfavorable conditions. The Lombard effect, which describes a rise in call amplitude with increasing ambient noise, is a widely exploited strategy by vertebrates to cope with interfering noise. In humans, the Lombard effect influences the lexical stress through differential amplitude modulation at a sub-call syllable level, which so far has not been documented in animals. Here, we bridge this knowledge gap with two species of Hipposideros bats, which produce echolocation calls consisting of two functionally well-defined units: the constant-frequency (CF) and frequency-modulated (FM) components. We show that ambient noise induced a strong, but differential, Lombard effect in the CF and FM components of the echolocation calls. We further report that the differential amplitude compensation occurred only in the spectrally overlapping noise conditions, suggesting a functional role in releasing masking. Lastly, we show that both species of bats exhibited a robust Lombard effect in the spectrally non-overlapping noise conditions, which contrasts sharply with the existing evidence. Our data highlight echolocating bats as a potential mammalian model for understanding vocal production control.

scholarly journals Convergences in the diversification of bats

2010 ◽  
Vol 56 (4) ◽  
pp. 454-468 ◽  
Author(s):  
M. Brock Fenton
Keyword(s):  
Litter Size ◽  
Duty Cycle ◽  
Adaptive Function ◽  
Small Litter ◽  
Echolocation Calls ◽  
Low Intensity ◽  
High Duty Cycle ◽  
Small Litter Size ◽  
Flower Visiting ◽  
Nasal Emission

Abstract Twenty-five characters or suites of characters from bats are considered in light of changes in bat classification. The characters include some associated with flower-visiting (two), echolocation (12), roosting (six), reproduction (two) and three are of unknown adaptive function. In both the 1998 and 2006 classifications of bats into suborders (Megachiroptera and Microchiroptera versus Yinpterochiroptera and Yangochiroptera, respectively), some convergences between suborders are the same (e.g., foliage roosting, tent building), but others associated with echolocation differ substantially. In the 1998 phylogeny convergences associated with echolocation (high duty cycle echolocation, nasal emission of echolocation calls) occurred among the Microchiroptera. In the 2006 phylogeny, they occur between Yinpterochiroptera and Yangochiroptera. While some traits apparently arose independently in two suborders (e.g., foliage-roosting, tent building, low intensity echolocation calls, noseleafs, nasal emission of echolocation calls, high duty cycle echolocation behaviour), others appear to have been ancestral (roosting in narrow spaces, laryngeal echolocation, stylohyal-tympanic contact, oral emission of echolocation calls, and small litter size). A narrow profile through the chest is typical of bats reflecting the thoracic skeleton. This feature suggests that the ancestors of bats spent the day in small crevices. Features associated with laryngeal echolocation appear to be ancestral, suggesting that echolocation evolved early in bats but was subsequently lost in one yinpterochiropteran lineage.

Echolocation and feeding behaviour of Taphozous mauritianus (Chiroptera: Emballonuridae)

1980 ◽  
Vol 58 (10) ◽  
pp. 1774-1777 ◽  
Author(s):  
M. B. Fenton ◽  
G. P. Bell ◽  
D. W. Thomas
Keyword(s):  
Long Range ◽  
Feeding Behaviour ◽  
Second Harmonic ◽  
Feeding Strategy ◽  
Rapid Rise ◽  
Constant Frequency ◽  
Insectivorous Bats ◽  
Sound Energy ◽  
Echolocation Calls ◽  
Human Ear

Observations of free-flying bats in the field in Zimbabwe indicated that Taphozous mauritianus uses multiharmonic constant frequency (CF) search calls followed by multiharmonic approach and terminal calls that combine shallow and steep frequency modulated (FM) sweeps during approaches to targets. The three phases of calls all have rapid rise times to full amplitude, and most of the sound energy is in the second harmonic; the fundamental is usually present (11–13 kHz), making the calls clearly audible to the unaided human ear. This combination of characters, but particularly the CF search calls, serves to distinguish these echolocation calls from those of other insectivorous bats. One light-tagged individual hunting insects reacted to targets at distances of about 3 m, suggesting a long-range feeding strategy.

Combining wave‐equation imaging with traveltime tomography to form high‐resolution images from crosshole data

Geophysics ◽  
1991 ◽  
Vol 56 (2) ◽  
pp. 208-224 ◽  
Author(s):  
R. Gerhard Pratt ◽  
Neil R. Goulty
Keyword(s):  
Wave Equation ◽  
High Resolution ◽  
Acoustic Wave ◽  
Equation Method ◽  
Single Frequency ◽  
Acoustic Wave Equation ◽  
Elastic Wave Equation ◽  
Traveltime Tomography ◽  
Combined Use ◽  
Frequency Components

Traveltime tomography is an appropriate method for estimating seismic velocity structure from arrival times. However, tomography fails to resolve discontinuities in the velocities. Wave‐equation techniques provide images using the full wave field that complement the results of traveltime tomography. We use the velocity estimates from tomography as a reference model for a numerical propagation of the time reversed data. These “backpropagated” wave fields are used to provide images of the discontinuities in the velocity field. The combined use of traveltime tomography and wave‐equation imaging is particularly suitable for forming high‐resolution geologic images from multiple‐source/multiple‐receiver data acquired in borehole‐to‐borehole seismic surveying. In the context of crosshole imaging, an effective implementation of wave‐equation imaging is obtained by transforming the data and the algorithms into the frequency domain. This transformation allows the use of efficient frequency‐domain numerical propagation methods. Experiments with computer‐generated data demonstrate the quality of the images that can be obtained from only a single frequency component of the data. Images of both compressional [Formula: see text] and shear wave [Formula: see text] velocity anomalies can be obtained by applying acoustic wave‐equation imaging in two passes. An imaging technique derived from the full elastic wave‐equation method yields superior images of both anomalies in a single pass. To demonstrate the combined use of traveltime tomography and wave‐equation imaging, a scale model experiment was carried out to simulate a crosshole seismic survey in the presence of strong velocity contrasts. Following the application of traveltime tomography, wave‐equation methods were used to form images from single frequency components of the data. The images were further enhanced by summing the results from several frequency components. The elastic wave‐equation method provided slightly better images of the [Formula: see text] discontinuities than the acoustic wave‐equation method. Errors in picking shear‐wave arrivals and uncertainties in the source radiation pattern prevented us from obtaining satisfactory images of the [Formula: see text] discontinuities.

Echolocation calls produced by Trachops cirrhosus (Chiroptera: Phyllostomatidae) while hunting for frogs

1981 ◽  
Vol 59 (5) ◽  
pp. 750-753 ◽  
Author(s):  
R. M. R. Barclay ◽  
M. B. Fenton ◽  
M. D. Tuttle ◽  
M. J. Ryan
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Pressure Level ◽  
Echolocation Calls ◽  
Low Intensity ◽  
Flight Cage ◽  
Trachops Cirrhosus

The echolocation calls produced by Trachops cirrhosus in the field and in a flight cage were recorded as they hunted for frogs. The calls were of low intensity (< 70 dB sound pressure level (SPL) at 10 cm), short (less than 1 ms), multiharmonic frequency modulated sweeps with energy from over 100 to around 50 kHz. During most successful attacks of frogs in the cage, these orientation sounds were produced by the bats which are also known to rely on frog calls to locate prey.

scholarly journals Ultra-low intensity noise, all fiber 365 W linearly polarized single frequency laser at 1064 nm

2020 ◽  
Vol 28 (8) ◽  
pp. 10960 ◽  
Author(s):  
Clément Dixneuf ◽  
Germain Guiraud ◽  
Yves-Vincent Bardin ◽  
Quentin Rosa ◽  
Mathieu Goeppner ◽  
...  
Keyword(s):  
Single Frequency ◽  
Intensity Noise ◽  
Low Intensity ◽  
Linearly Polarized ◽  
Frequency Laser

Echolocation calls of some bats of Gujarat, India

Mammalia ◽  
2020 ◽  
Vol 84 (5) ◽  
pp. 483-492
Author(s):  
Tariq Ahmed Shah ◽  
Chelmala Srinivasulu
Keyword(s):  
Forest Regeneration ◽  
Cross Validation ◽  
Function Analysis ◽  
Insect Pest ◽  
Species Level ◽  
Constant Frequency ◽  
Echolocation Calls ◽  
Insect Pest Control ◽  
Non Invasive ◽  
Leave One Out

AbstractBats play an important role by providing ecosystem services including pollination, seed dispersal, forest regeneration and insect pest control and also serve as bio-indicators. In the present study, we present an acoustic guide to the calls of nine species of bats from Gujarat belonging to families Rhinopomatidae (Rhinopoma hardwickii, Rhinopoma microphyllum), Emballonuridae (Taphozous melanopogon, Taphozous longimanus and Taphozous nudiventris), Rhinolophidaea (Rhinolophus lepidus), Hipposideridae (Hipposideros galeritus) and Vespertilionidae (Scotophilus heathii, Pipistrellus ceylonicus). Discriminant function analysis was used to classify the bat calls to the species level using leave-one-out cross validation. Analysis was carried out separately for constant frequency (CF) calls and frequency-modulated (FM) calls. Bats echolocating with CF calls were classified with 100% success, while in the case of FM calls, the calls were classified with 66.7% accuracy. In species-rich communities, care should be taken while using echolocation calls to identify bats producing FM calls. More such call libraries of bats from other parts of India are needed for non-invasive documentation of chiropteran fauna in different biogeographic zones.

Efficient Generation of High-Reynolds-Number Homogeneous Turbulence by Disturbances Composed of Two Frequency Components

2015 ◽  
Author(s):  
Kotaro Takamure ◽  
Shigehira Ozono
Keyword(s):  
Reynolds Number ◽  
High Reynolds Number ◽  
Random Phase ◽  
Homogeneous Turbulence ◽  
Single Frequency ◽  
Tunnel Length ◽  
Driving Mode ◽  
Spectral Peaks ◽  
Frequency Components ◽  
High Reynolds

We attempted to determine the number of frequency components required for efficient turbulence generation using a multi-fan type wind tunnel where 99 fans were driven to generate turbulence. In a previous study, a random-phase mode was applied, where an input signal composed of forty frequency components was fed to each fan with quasi-random phases. Using this driving mode, we achieved high-Reynolds-number homogeneous turbulence of Reλ ∼ 750 in a relatively short distance. In the present study, in order to understand the elementary process of the evolution, one single frequency or two frequencies were used, instead of forty. When using the single frequency, initial dominant spectral peaks remain at lower frequencies over the tunnel length. In the case of two frequencies, f1 and f2 (f1 = n1f0 and f2 = n2f0; n1 < n2), where n1 and n2 are integers, and f0 is defined as the reciprocal of a basic input data period, the turbulence characteristics depend on the relation between n1 and n2. When n1 and n2 are not coprime (i.e., n2 can be divided by n1), dominant spectral peaks remain over the tunnel length as in the case of using a single frequency, but when coprime (i.e., n2 cannot be divided by n1), the spectral shape becomes relatively smooth with the initial dominant peaks disappearing. However, it was found that the development of turbulence is much slower for the two-frequency case than for the forty-frequency case.

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