Animals who try to sound 'bigger' are good at learning sounds

JULY 7, 2020

by Max Planck Society

Some animals fake their body size by sounding bigger than they actually are. Maxime Garcia from the University of Zurich and Andrea Ravignani from the Max Planck Institute for Psycholinguistics studied 164 different mammals and found that animals that lower their voices to sound bigger are often skilled vocalists. Both strategies—sounding bigger and learning sounds—are likely driven by sexual selection, and may play a role in explaining the origins of human speech evolution.

"If you saw a chihuahua barking as deep as a rottweiler, you would definitely be surprised," says Andrea Ravignani, a researcher at the MPI and the Dutch Sealcentre Pieterburen. Body size influences the frequency of the sounds animals produce, but many animals found ways to sound smaller or bigger than expected.

"Nature is full of animals like squeaky rottweilers and tenor chihuahuas," explains Ravignani. Some animals fake their size by developing larger vocal organs that lower their sound, which makes them sound larger than you would expect. Other animals are good at controlling the sounds they produce. Such strategies (called dishonest signalling by biologists) could be driven by sexual selection, as males with larger body size or superior singing skills (hitting very high or low notes) attract more females (or vice versa).

Garcia and Ravignani wondered whether some animals may have learned to make new sounds as a strategy to attract mates. Few animal species are capable of vocal learning, among them, mammals such as seals, dolphins, bats and elephants. For instance, seals can imitate sounds, and some seals copy call types of successfully breeding individuals. Would animals who often 'fake' their body size also be the ones capable of learning new sounds?

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Sounds of intense emotion may be universal language across species, study shows

JULY 11, 2019

by Katie Willis, University of Alberta

People can tell how other people are feeling by the sounds they make and now, new research from the University of Alberta shows that may also apply to different animals.

"The idea is that some species (those that are vocal learners) can understand other species' vocalizations," explained psychology Ph.D. student Jenna Congdon, who led a new study that showed both humans and black-capped chickadees can detect intense emotions such as fear or excitement in other species.

"For instance, a songbird is able to understand the call of distress of a different type of songbird when they are in the presence of a predator, like an owl or a hawk. Or, for example, if your friend scared you and you screamed. Both of these are high-arousal vocalizations, and being able to understand what that sounds like in a different species can be very useful."

Under the supervision of neuropsychologist Chris Sturdy, Congdon conducted two experiments, one examining chickadees and another examining humans. In the experiments, participants distinguished between high- and low-arousal vocalizations produced by other species, including alligators, chickadees, elephants, humans, pandas, piglets, ravens, macaques and tree frogs. Human subjects were able to identify high arousal in different species.

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In both love and war, alligators signal size by bellowing

Date: May 12, 2017

Source: University of Vienna]

In alligators and other crocodilian species, being bigger than your conspecifics can have decisive benefits: Females only accept males larger than themselves as mates and larger alligators are much more likely to win territorial fights. However, direct physical confrontations can lead to lethal injuries so it would be advantageous if fights could be avoided by individuals reliably signalling their body size to potential mates and rivals early on. One way to achieve this is by "honest" acoustic cues to body size in vocalizations. A team around Tecumseh Fitch at the Department of Cognitive Biology at the University of Vienna has now identified cues to body size in calls of American alligators, which is the first finding of this kind in reptiles.

American alligators produce very low-pitched rumbling roars, so called "bellows," year-round and most frequently during mating season. Interestingly, the bellowing displays differ between the sexes, as study co-author Kent Vliet from the University of Florida had previously described: Only male alligators produce a "water dance," visible due to water droplets sprinkling over their backs, preceding the audible bellow.

For the current study, lead-author Stephan Reber and Judith Janisch of the University of Vienna recorded the bellows of 43 adult American alligators at the St. Augustine Alligator Farm Zoological Park in Florida. Then the curators of the institution, Kevin Torregrosa and Jim Darlington, together with the two researchers, measured the head and total body length of all the alligators up close with measuring tapes and hand-held laser-distance-measurement devices.

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Mice Sing Love Songs Like a Jet Engine

By Stephanie Pappas, Live Science Contributor | October 11, 2016 07:46am ET

Ultra-high pitched mouse squeaks have something in common with the roar of a jet engine. New research finds that the rodents make ultrasound bleeps by creating a small air jet in their windpipes, employing a mechanism previously seen only in jet engines and high-speed subsonic flows.

The ultrasonic whistles are important because rodents use them to sing mating songs and make announcements about their territory. The sounds are too high in frequency to be detected by the human ear.

Until now, though, no one knew exactly how these whistles were produced. Researchers led by biologist Coen Elemans of the University of Southern Denmark used high-speed camera scopes to capture images of the larynxes, or voice boxes, of mice as the animals made their vocalizations. The cameras captured 100,000 frames per second for analysis. 

Two competing hypotheses had been put forward to explain how the ultrasonic vocalizations are made. The first suggested that the sounds are the result of superficial vocal-cord vibrations; essentially, air moves through the vocal cords as it would for any typical vocalization. However, the videos showed that the vocal cords weren't vibrating, even superficially.

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Cricket's chirp may have 'predatory roots'

By Victoria Gill

Science reporter, BBC News

10 December 2015 

The song of the male Angnotecous obscurus cricket is of such a high frequency that it is difficult to hear

Scientists have discovered that the chirps of some crickets could be a cunning way to "startle" potential mates into revealing their location.

The Dartmouth College team discovered the insects' communication system and studied females' reactions to the males' songs.

They say the call is likely to have evolved from males impersonating hunting bats and startling females.

Females' shuddering response appears to allow males to locate a mate.

Close examination of females' nervous systems suggested that this shudder evolved from a startle reflex, the researchers say.

The findings are published in the journal Current Biology.

Lead researcher Prof Hannah ter Hofstede investigated this unusual insect duet after a colleague presented some recordings of the insects' particularly high frequency chirps.

"It struck me as very strange that these crickets would use such high frequencies for mating purposes," the scientists said.

Other cricket species avoid sounds at these frequencies, which are similar to the sounds that bats make when navigating and hunting.

Escape behaviour

Prof ter Hofstede used playback experiments - playing males' songs through speakers - to test females' reaction to the high, bat-like chirps.

"I expected the females to walk to the speaker, because this is the usual behaviour for female crickets, but they did not do this - [they instead] made a small jerking motion after each male call," she explained.

"From many observations of males and females together, I noticed that it was always the male walking to the female when she produced these vibrational signals."

Read on ...

Shell’s US Arctic drilling will harass thousands of whales and seals

Exploratory drilling, seismic testing and ice-breaking activities threaten to expose whales to damaging sounds, and ‘a deaf whale is a dead whale’

Rose Hackman in New York

Friday 5 June 2015 17.46 BSTLast modified on Friday 5 June 201520.00 BST

Royal Dutch Shell’s plans for exploratory drilling in the US Arctic this summer will involve the harassment of whales and seals by the thousands, an application document filed by Shell to the National Marine Fisheries Service (NMFS) reveals.

Most notably, Shell estimates its Arctic activities will expose more than 2,500 bowhead whales, more than 2,500 gray whales and more than 50,000 ringed seals to continuous sounds and pulsed sounds, deemed damaging enough to constitute harassment.

The bowhead whale is listed under the US Endangered Species Act. By Shell’s own estimate, 13% of the overall population of bowhead whales still alive are potentially harassed .

The number of gray whales potentially harassed also constitutes 13% of the overall population, while the number of ringed seals potentially harassed amounts to 16%. Under the ESA, the ringed seal is classified as threatened.

Under the Marine Mammal Protection Act, the government may allow for the “taking” or “harassment” of marine mammals, so long as the number taken is small and the impact on the species negligible.

But environmental groups argue the numbers affected by the Shell plans are not small, nor will the impact on species be negligible.

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Brain Picks out Salient Sounds from Background Noise by Tracking Frequency and Time, Study Finds

July 23, 2013 — New research reveals how our brains are able to pick out important sounds from the noisy world around us. The findings, published online today in the journal eLife, could lead to new diagnostic tests for hearing disorders.

Our ears can effortlessly pick out the sounds we need to hear from a noisy environment -- hearing our mobile phone ringtone in the middle of the Notting Hill Carnival, for example -- but how our brains process this information (the so-called 'cocktail party problem') has been a longstanding research question in hearing science.

Researchers have previously investigated this using simple sounds such as two tones of different pitches, but now researchers at UCL and Newcastle University have used complicated sounds that are more representative of those we hear in real life. The team used 'machine-like beeps' that overlap in both frequency and time to recreate a busy sound environment and obtain new insights into how the brain solves this problem.

In the study, groups of volunteers were asked to identify target sounds from within this noisy background in a series of experiments.

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