Bats enhance their call identities to solve the cocktail party problem

Hase, Kazuma; Kadoya, Yukimi; Maitani, Yosuke; Miyamoto, Takara; Kobayasi, Kohta I.; Hiryu, Shizuko

doi:10.1038/s42003-018-0045-3

Cited by 29 publications

(19 citation statements)

References 40 publications

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“…The alternating short and long IPIs used by P. abramus and E. fuscus seem designed to probe into the entire scene, out to the longest delays in the room, while next looking closely to nearby objects to facilitate rapid guidance reactions. Miniopterus fuliginosus uses FM sounds similar to those recorded in flights here to hunt for flying insects (Hu et al, 2011), and they change the terminal frequency of their FM sweeps when flying in each other's company to avoid mutual jamming (Hase et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

Biosonar interpulse intervals and pulse-echo ambiguity in four species of echolocating bats

Simmons

Hiryu

Shriram

2019

Journal of Experimental Biology

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In complex biosonar scenes, the delay of echoes represents the spatial distribution of objects in depth. To avoid overlap of echo streams from successive broadcasts, individual echolocation sounds should only be emitted after all echoes of previous sounds have returned. However, close proximity of obstacles demands rapid pulse updates for steering to avoid collisions, which often means emitting a new sound before all of the previous echoes have returned. When two echo streams overlap, there is ambiguity about assigning echoes to the corresponding broadcasts. In laboratory tests of flight in dense, cluttered scenes, four species of echolocating bats exhibited different patterns of pulse emissions to accommodate potential pulse-echo ambiguity. Miniopterus fuliginosus emitted individual FM pulses only after all echoes of previous pulses had returned, with no alternating between long and short intervals. Pipistrellus abramus and Eptesicus fuscus alternated between emitting long FM pulse intervals to receive all echoes before the next pulse, and short intervals to update the rapidly changing scene while accepting partial overlap of successive echo streams. Rhinolophus ferrumequinum nippon transmitted CF/FM pulses in alternating short and long intervals, usually two to four closely spaced sounds that produced overlapping echo streams, followed by a longer interval that separated echo streams. Rhinolophus f. nippon is a statistical outlier from the three FM species, which are more similar to each other. The repeated overlap of CF/FM echo streams suggests that CF components have a distinct role in rejection of clutter and mitigation of ambiguity.

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Section: Discussionmentioning

confidence: 99%

Biosonar interpulse intervals and pulse-echo ambiguity in four species of echolocating bats

Simmons

Hiryu

Shriram

2019

Journal of Experimental Biology

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“…Consequently, there are few examples of bats that emit frequencymodulated (FM) echolocation calls to match conspecific calls. However, some FM bats clearly do respond to auditory feedback from conspecifics either by not producing echolocation calls [20] or by modifying call frequency in the presence of conspecifics [21][22][23][24] or ambient noise [25,26]. In contrast, bats that rely on constant frequency (CF) echolocation calls produce long duration sounds that are centered on a narrow frequency band, so it is relatively easy to determine if the frequency of an echolocation call emitted while the bat is at rest is the same or different than another individual.…”

Section: Saccopteryx Bilineatamentioning

confidence: 99%

Behaviour, biology, and evolution of vocal learning in bats

Vernes

Wilkinson

2019

Preprint

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The comparative approach can provide insight into the evolution of human speech, language, and social communication by studying relevant traits in animal systems. Bats are emerging as a model system with great potential to shed light on these processes given their learned vocalisations, close social interactions, and mammalian brains and physiology. A recent framework outlined the multiple levels of investigation needed to understand vocal learning across a broad range of nonhuman species including cetaceans, pinnipeds, elephants, birds and bats. Herein we apply this framework to the current state of the art in bat research. This encompasses our understanding of the abilities bats have displayed for vocal learning, what is known about the timing and social structure needed for such learning, and current knowledge about the prevalence of the trait across the order. It also addresses the biology (vocal tract morphology, neurobiology, and genetics) and phylogenetics of this trait. We conclude by highlighting some key questions that should be answered to advance our understanding of the biological encoding and evolution of speech and spoken communication.

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“…These previous findings confirm that similarities in the FM pattern between sounds, and not the simple spectral pattern, cause jamming of echolocation at a higher order, such as target ranging, which utilizes the template of their own echolocation sounds Raver, 1996, 2000). In fact, during group flight, M. fuliginosus reportedly extend the frequency difference in individual TFs while increasing the intensity of emitted pulses and lengthening the pulse duration (Hase et al, 2018). Furthermore, Hase et al (2018) also demonstrated that the slight TF shift decreases the similarity between the dExp signals.…”

Section: Response Time Of the Tf Shiftmentioning

confidence: 93%

“…In fact, during group flight, M. fuliginosus reportedly extend the frequency difference in individual TFs while increasing the intensity of emitted pulses and lengthening the pulse duration (Hase et al, 2018). Furthermore, Hase et al (2018) also demonstrated that the slight TF shift decreases the similarity between the dExp signals. Taken together, echolocating bats could employ various strategies to avoid acoustic interference; they could improve the signal-to-noise ratio of their echoes by emitting louder and longer pulses, which is referred to as the Lombard effect.…”

Section: Response Time Of the Tf Shiftmentioning

confidence: 93%

“…By changing the value of a, jamming sounds with different frequency sweeps (including CF sounds) were created ( Fig. 1): one CF sound of 45 kHz, which is slightly lower than the average TF (approximately 48 kHz) of this bat species (Hase et al, 2018); and four different types of FM sound with a minimum frequency of 45 kHz, a maximum frequency of 85 kHz and a bandwidth of 40 kHz: (1) downward exponential (dExp), (2) upward exponential (uExp), (3) downward linear (dLin) and (4) upward linear (uLin) FM sounds. The signal length of all sounds was 3 ms.…”

Section: Sound Stimulimentioning

confidence: 99%

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Adaptive frequency shifts of echolocation sounds in Miniopterus fuliginosus according to the frequency-modulated pattern of jamming sounds

Maitani

Hase

Kobayasi

et al. 2018

Journal of Experimental Biology

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When flying in a group, echolocating bats have to separate their own echoes from pulses and echoes belonging to other individuals to extract only the information necessary for their own navigation. Previous studies have demonstrated that frequency-modulated (FM) bats change the terminal frequencies (TFs) of downward FM pulses under acoustic interference. However, it is not yet clear which acoustic characteristics of the jamming signals induce the TF shift according to the degree of acoustic interference. In this study, we examined changes in the acoustic characteristics of pulses emitted by Miniopterus fuliginosus while presenting jamming stimuli with different FM patterns to the bat flying alone. Bats significantly altered their TFs when responding to downward (dExp) and upward (uExp) exponential FM sounds as well as to a constant-frequency (CF) stimulus, by approximately 1-2 kHz (dExp: 2.1±0.9 kHz; uExp: 1.7 ±0.3 kHz; CF: 1.3±0.4 kHz) but not for linear FM sounds. The feature common to the spectra of these three jamming stimuli is a spectrum peak near the TF frequency, demonstrating that the bats shift the TF to avoid masking of jamming sounds on the TF frequency range. These results suggest that direct frequency masking near the TF frequency range induces the TF shift, which simultaneously decreases the similarity between their own echolocation sounds and jamming signals.

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Bats enhance their call identities to solve the cocktail party problem

Cited by 29 publications

References 40 publications

Biosonar interpulse intervals and pulse-echo ambiguity in four species of echolocating bats

Biosonar interpulse intervals and pulse-echo ambiguity in four species of echolocating bats

Behaviour, biology, and evolution of vocal learning in bats

Adaptive frequency shifts of echolocation sounds in Miniopterus fuliginosus according to the frequency-modulated pattern of jamming sounds

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