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 The Alpha stable distribution in ocean ambient noise modelling

2019 ◽  
Vol 283 ◽  
pp. 08002
Author(s):  
Guoli Song ◽  
Xinyi Guo ◽  
Li Ma
Keyword(s):  
Normal Distribution ◽  
Ambient Noise ◽  
Stable Distribution ◽  
Characteristic Exponent ◽  
Statistical Modelling ◽  
Gaussian State ◽  
Sample Mean ◽  
Noise Interference ◽  
Interference Noise ◽  
Non Gaussian

In view of the non-Gaussian of ocean ambient noise, the  stable distribution is applied to the statistical modelling. Firstly, the one-to-one correspondence between the four parameters of stable distribution and the sample mean, variance, skewness and kurtosis are established according to physical meaning. Then, numerical simulations are conducted to analyze the suitability of stable distribution for non-Gaussian ambient noise. In the case of white noise interference, noise is divided into Gaussian state, leptokurtic, and platykurtic separately. The parameters of stable distribution are estimated by the sample quantile and characteristic function method jointly. The simulation results show that, in the Gaussian state,  stable distribution is equivalent to normal distribution. As for leptokurtic distribution, stable distribution is much better than normal distribution, indicating absolute predominance in impulse-like data modeling. But it is not adaptive for low kurtosis state because its characteristic exponent can’t be bigger than two. Finally, the result is verified by ambient noise collected in three environmental conditions, such as quiet ambient noise, airgun interference noise and ship noise. In all three cases,  stable distribution shows good adaptability and accuracy, especially for the airgun dataset it is far superior to normal distribution.

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.

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.

scholarly journals Lombard effect, ambient noise and willingness to spend time and money in a restaurant amongst older adults

2020 ◽  
Vol 148 (4) ◽  
pp. 2752-2752
Author(s):  
Rachael N. Piper ◽  
Brianna Legner ◽  
Alyse Ruda ◽  
PASQUALE BOTTALICO
Keyword(s):  
Older Adults ◽  
Ambient Noise ◽  
Lombard Effect

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.

The echolocation calls of hoary (Lasiurus cinereus) and silver-haired (Lasionycteris noctivagans) bats as adaptations for long- versus short-range foraging strategies and the consequences for prey selection

1986 ◽  
Vol 64 (12) ◽  
pp. 2700-2705 ◽  
Author(s):  
Robert M. R. Barclay
Keyword(s):  
Prey Selection ◽  
Foraging Strategy ◽  
Prey Detection ◽  
Constant Frequency ◽  
Insectivorous Bats ◽  
Lasiurus Cinereus ◽  
Echolocation Calls ◽  
Close Range ◽  
Search Approach ◽  
Lasionycteris Noctivagans

Amongst aerial-feeding insectivorous bats, differences in the design of echolocation calls appear to be associated with differences in foraging strategy. Recordings and observations of hoary (Lasiurus cinereus) and silver-haired (Lasionycteris noctivagans) bats in Manitoba, Canada, support such an association. Lasionycteris noctivagans use multiharmonic search–approach calls with an initial frequency sweep and a constant frequency tail. Such calls are suited for bats foraging in the open but near obstacles, and pursuing prey detected at relatively close range. This is the foraging strategy employed by this relatively slow, manoeuverable species. Lasiurus cinereus employ single harmonic search–approach calls that are low (20–17 kHz), essentially constant frequency signals. Calls of this design are suited for long-range target detection in open air situations, the foraging strategy used by L. cinereus. Differences in call design may explain dietary differences between the two species. Lasiurus cinereus consistently prey on large insects. The low, constant frequency design of their calls means that small insects are detectable only at close range and are thus difficult for this fast-dying bat to catch. The broad-band calls used by L. noctivagans do not restrict prey detection and these bats prey on a wider range of insects. Similar restrictions on prey detection, caused by echolocation call specializations, may be important in producing what might otherwise be considered active prey selection by some insectivorous bats.

scholarly journals Sometimes noise is beneficial: stream noise informs vocal communication in the little torrent frog

2016 ◽  
Author(s):  
Longhui Zhao ◽  
Jichao Wang ◽  
Steven E. Brauth ◽  
Yezhong Tang ◽  
Jianguo Cui
Keyword(s):  
Ambient Noise ◽  
Animal Species ◽  
Vocal Communication ◽  
Information Source ◽  
High Amplitude ◽  
Dominant Frequency ◽  
Noise Sources ◽  
Running Water ◽  
Sound Communication ◽  
Low Amplitude

Many animal species use acoustic signals for social communication including attracting mates, defending resources and assessing risks. Nevertheless, a variety of ambient noise sources often interfere with sound communication and efficient decision making. In the present study we identified an exception to this generalization in a streamside species, the little torrent frog (Amolops torrentis) which communicates in an environment in which stream noise is always present. To show that stream noise can act as a biological signal which reflects the character of the microhabitat of the sender, we performed female phonotaxis experiments using synthetic male advertisement calls. Calls with high dominant frequency exceeding the ambient stream noise band and calls with lower dominant frequency centered at the frequency range of best hearing were used. The signal-noise ratio was varied by adding noise to each kind of call. We found that females prefer calls with high amplitude stream noise added to those with low amplitude stream noise added for both the high and low dominant frequency stimulus pairs; however, the sound of running water had no attractiveness in the absence of calls. These results show that stream noise can function as an information source by enhancing the attractiveness of calls in the torrent frog. Stream noise associates closely with rocks, topographies and vegetation; thus the sound of running water may provide useful information to signal receivers about variations in microhabitats and thereby act on sexual selection under some circumstances. These data therefore contribute to our understanding of how the perception of mate attractiveness in heterogeneous ecological environments can evolve.

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