Chinese disruption is smooth and not lingering, as well as bird language

The following article comes from WeChat public account: Global Science, author Global Science

Article ｜ Adam Fishbein

Translation ｜ Sun Jia

During the new crown epidemic, many people love to listen to birds than before. After listening, we can't help but think of the similarities between Bird Ming and human music and language: the high sound of the high sound of the North American song and the bass humming, the red-winged blackbird "" ”里-—— — 的 There is a structure similar to sentences. When the white throat band (White-Throated Sparrow) opens his mouth, he can make a cheerful whistle.

In traditional definitions, Birdsong refers to the long and complex call from birds to attract spouse and defended territory, which belongs to the acquired acquisition. In modern categories, the call of birds and birds (Bird Call), the latter is usually shorter, simpler, and more diverse (such as sending signals on predators and food), which is congenital instinct. However, these definitions are not static, and some species are simpler than calls. In this article, "Bird Ming" specifically refers to complex long sounds, rather than short "唧" and "啾" sounds.

Researchers and amateur enthusiasts talked about the terms used when Bird Mingson used, reflecting the similarities between Birds and music and language in human ears. When analyzing the researchers, the birds are often decomposed into smaller units- "notes" or "syllable"; and then combine syllables into sequences, called "phrase" or "themes" (themes) "(Motif), each phrase or theme has a unique rhythm and speed. We use these terms to record the possible characteristics of bird singing, such as the number of syllables, or the arrangement mode of a phrase. Such a description method is similar to the syntax term used by humans to mark the word relationship in the sentence, or the notes of the notes in music in music.

On the other hand, how do birds think of the above characteristics? What will the birds in the bird's ears look like? Recently, my colleagues and I have carried out related research, and more and more scientists around the world are doing similar work. The results of the study show that the birds in the bird's ears are not the same as the birds in the human ear. In addition, the birds listening to birds seem not the melody that attracts human ears, but the fine acoustic details of the human perception range in the cry.

Beyond the melody

As early as the 1960s, Bird Ming researchers have found that the sounds in the ears of birds are different from our ideas. There is a classic experimental method that studies wild birds in response to birds, named "Back Experiment". In this experiment, the researchers played similar song recording to birds and recorded their behavioral response. Many birds' response to similar typical tweeting recording is the same as encountering the invaders of the territory -they are close to the speakers of the playback, and they circulate the invaders around the sound source, and at the same time make a threatening call or tweet. Through the different reactions of the birds' sounds and artificial sounds, researchers can understand which calling features will be valued by the birds. In the previous digital era, the researchers will use the tape recorder to record the birds, then cut the stitching tape, re -arrange the syllable, or shorten the interval of the note to create artificial calls. Today, with digital recording equipment and sound editing software, it is much simpler to create artificial sounds.

In a classic background study in the 1970s, Stephen T. Emlen, Cornell University, studied the sound response of Indigo Bunting. The vibrant blue heroes will make a song composed of syllables, and almost always send out two syllables at a time. The wild bird guide often emphasizes this pairing syllable mode when describing the sound of colorfulness. In the spectrum map, this model is very obvious. The spectrum diagram is a chart that calls the tweet, describing how the frequency and amplitude of the sound change will change over time. In perception, the frequency is equivalent to sound height, and the amplitude is equivalent to loudness. Regardless of the sound of the sound or the spectrum chart, humans are easy to identify this pairing syllable mode.

In Emlin's research, the researchers edited the sound of 靛 鹀 鹀 to play the artificial tweeting of the syllables to them. After hearing this recording, Lan Lanyu showed the same intensity of territorial response when he heard the natural tweet. This result shows that although humans feel that the syllable mode is highly recognizable, this model is not important for bird recognition. If the bird watching guideline lets Cai Cai write itself, the call it describes is definitely very different from us.

The sound waveform diagram (top) and spectrum diagram (below) depict the tweet of 靛 鹀 鹀. The X -axis of the spectrum indicates the time, and the y -axis represents the frequency or "sound height" of the sound.

Laboratory studies have found that there are many similarities in auditory sensitivity in auditory sensitivity, including the threshold of distinguishing the difference in tone, and the threshold of the sound interval. At the same time, the results of the study also show that there are amazing differences between birds and humans in the ability to recognize sound sequences and acoustic details.

There is a very key to the results of the laboratory research: Once the tone rises or decreases, the performance of bird recognition in the same melody is worse; humans have this identification ability. If you play a happy birthday song on the piano, we can recognize this song regardless of the sound of the sound. In the 1980s and 1990s, Stewart H. Hulse and colleagues at the University of John Hopkins University in the United States and colleagues showed that for birds, even if the basic mode is maintained Unchanged, once the sound sequence changes, the tune sounds different. Therefore, the melody we hear from Bird Mings may be very different from the birds. Subsequent research supported this assumption. In 2016, Micah Bregman also at the University of California, San Diego, the University of California. The team led by his leader said: European Starling can recognize the transformed sound sequence, provided that the sound must be removed. All fine acoustic details. This result fully shows the importance of fine details in birds to hearing birds.

Ear that values ​​details

The description of sound waveforms can be decomposed into two levels: envelope and fine structure. The package consists of the slow fluctuation of the waveform amplitude, while the fine structure consists of the rapid fluctuation of the frequency and amplitude. In other words, the fine structure is the change of sound in milliseconds. Historically, many bird Ming researchers ignored the fine structure, partly because of the use of spectrum or spectrum. These charts can help people understand Bird Ming intuitively, but it is difficult to make people aware of the changes in the fine structure at a glance. However, as long as the waveforms of a single bird whisper are magnified, these fine acoustic details can be revealed.

Robert Dooling of the University of Maryland, the University of Maryland, created a study of the fine structure of birds with collaborators. For decades, he and his colleagues have been trying to evaluate the ability of bird recognition of the fine structure of birds. In a key study published in 2002, they tested the difference between birds and humans to distinguish the differences in sound structure. All bird species they tested, including Zebra Finch, domesticated Domestic Canary, and Budgerigar -are much better than humans. Birds can distinguish the fine structure differences, two to three times smaller than human subjects. The exact physiological mechanism behind the sensitivity of bird superhuman is still unknown, but it may be related to their internal signs. The inner ear structure of the birds is different from us. The cochlea is relatively short, slightly curved instead of the roll.

In 2015, I studied graduate students at the University of Maryland and began to study the comparison of Bird Ming and human language. At that time, I did not consider the fine structure too much, but intended to study the language and grammatical ability of birds. With the deepening of research and the increase in the number of bird experiments I made, I gradually realized that the key to understanding the content of the bird's reputation may be fine acoustic details, not the order of the syllable.

Carefully analyze the tweet of 鹀 析 析 析 may be more finely acoustic details, not a pair of syllables. The first information chart (above) describes the sound waveform of the beginning of the sound. In the highlighting part of the second syllable, you can see that the frequency and amplitude in a single syllable occur quickly in the time range of the millisecond level (below).

In Du Lin's study of the fine structure of the sound in 2002, the champion of the test bird was spots. This lively small narrow bird native to Australia is the most popular species in the study of modern birds based on laboratory. This is mainly because it can make a tweet and a lot of reproduction in the circle of maintenance. The only male birds can make a bark, and the barking is relatively simple -three to eight syllables form a single theme, which appears repeatedly, and the order is usually the same. Therefore, studying the tweeting of spasm and spurs is simpler than studying other birds. Because the male birds learn the syllable and syllable sequence from the "mentor" (usually their father), people will naturally think that the two levels of syllables and sequences are important for the auditory perception of spots and cysts.

We tested this idea in a 2018 study. The study examines the difference between the theme of natural birds and the theme of the syllable sequence or randomly disrupted the theme of the theme of the syllable sequence. We train birds to report whether they can hear the differences between sounds: they first hear the repeated sounds first, and then press the button to start the test. The sound in the test may change or remain unchanged. If the bird pecks a button when the sound changes, the bird will get food rewards; if the sound is pecking the button when the sound is unchanged, it will be considered as a guess, and the indoor light will go out. We use the above methods to evaluate the resolution ability of the birds to duplicate sounds (the theme of natural birds) and new sounds (syllable sequences upside down or randomly disrupting the theme of artificial bird singing). Of course, from the perspective of birds, they just want to win delicious food.

Interestingly, the performance of the spots of the chest and the cylinder is almost perfect in the upside -down syllables that the ears of humans are unaware of; In the upside -down syllable, it is mainly a fine structure that changes, so it is not surprising that birds win. However, they encountered major difficulties in distinguishing sequences, which was unexpected. Not only because the changes in the sequences in these random syllables are obvious in humans, but because of learning tweets, the spots of the busty bird bird will produce song syllables with a specific sequence. The difficulties of their perception of random syllables may mean that for these ring poultry, although the syllable sequence may be important in the learning process, it does not carry much information in the communication. In view of the results of these artificial bird singing experiments, my colleagues and I began to think about the relationship between the perception of the fine structure of the sound and the communication between natural birds. Although the upside -down syllable is impressive, the birds will never make such a sound. Therefore, the next theme we study is: the degree of recognition of fine acoustic changes in natural birds in birds.

My colleagues published another paper in 2018, which mentioned that the spots of the busty grass can hear the small differences of the fine structure of each other. These tiny differences contain information of gender and individual identity. In order to study the perception of the spots of the spascoon, we have used their characteristics: there are only a single theme, the same syllables, and the same order of repeatedness -at least the researchers heard the same. In fact, the sound of the syllables in the theme of the spots of the chest, the sound of the syllable in the theme, each time there is a slight difference. We tested the ability to identify this difference in busty grass and birds, and found that the birds could easily identify the differences.

In the spectrum diagram shown, the top picture is the natural tweeting theme emitted by the bustybes, as the background sound; the middle picture reversed the second syllable in the natural theme, which is one of the new sounds that are placed to the birds; the bottom picture of the picture; The order of the syllables in the natural theme disrupted as another new voice. The white circle is marked with upside down or random arrangement.

This result means that although we hear, the singing of the strange and the cypress is repeated like the same theme, but the birds sound different. We guess that they may perceive a rich information library, including emotional, health, age, individual identity, and more fine structure information that our ears cannot detect. The sound of other birds sounds duplicate in humans. We have reason to believe that they should also have the ability to perceive the chest -like grass and cylinder.

You may guess: the small sound fluctuation in the bird Ming is only accidental or random results, as if baseball pitcher throws into the curve ball of the home base, it sometimes changes, but it does not intend to do it. In fact, the key to regulating fine structures may be the resonance of birds. Humans use the single source of the top of the neck -called the organ of the throat -to produce sounds, and use their mouths and tongue to shape them into language; the birds are uniquely double -branch structure of the top of the lungs -called Mingming The organ of the tube -generate sound. There are two sound sources in the ring tube, one on the left and right branches, which can be separated independently. The most important thing is that the contraction speed of the muscle of the ring tube is the fastest in vertebrate muscles, which can achieve millisecond level control. It can be seen that the fine acoustic changes in the sound of birds are not inadvertently errors in the beak. Birds can not only perceive this change, but also control it.

Dance of the tube

The above studies have shown that the way bird listening to the sound is different from our previous ideas. Humans listening to music and speeches must rely on the melody and sentence structure in it. Therefore, when we hear birds, we can't help but project the "melody" and "structure". But the order of syllables does not seem to be important for birds, and some birds are difficult to distinguish by simple order changes. In human beings, once the language or music changes, the information or melody passed will be completely disturbed. But the most important thing for birds seems to be the acoustic details of a single syllable in the tweet, which has nothing to do with the sequence of syllables. Moreover, the details they hear beyond the scope of human ears.

To understand the birds in the bird's ears, taking dance for example may be better than language or music. When learning dance, if you want to do the right, you have to follow the correct order. For example, I have studied the actions of Lindy Circle and Charleston in the swing dance class. In this dance, once a transition is messed up, it will cause the structure of this action. But for those who watch dance, there are not much information. The audience pays attention to the skills, rhythm and diversity of action, not the order of action. Birds may be the same. For the birds who make a call, the correct syllable order is very important for the correct "movement"; but for the listening bird, the most important thing is the single action itself.

But this does not mean that Bird Ming's language or music is not obvious. When humans learn to speak, the sounds that are repeated when birds learn by birds -this ability is called sound learning, which is quite rare in the animal world. Our close relatives, and other primates, seem to be unable to do this. Some mammals do show a certain degree of sound learning ability (such as bats, whales, elephants, seals, and sea lions), but none of them have reached human and certain birds (specifically, poultry, parrot and hummingbirds) can reach The sound imitation level. Other types of birds -including pigeons, chicken and owl -nor have sound learning ability. We still need to understand how birds perceive birds. Some studies have shown that there is evidence that the calls of birds convey the specific information of their environment, such as food or predators. But we don't know if there are similar information in the sound of birds -maybe it is stored in the fine structure. We don't know how the birds perceive the fine structure in the natural environment in the natural environment -in the natural environment, the sound will echo between trees and buildings, and it will be affected by noise in the environment.

In addition, it is traditionally believed that Bird Ming is a male behavior in a strict sense, and this view has also been challenged. Recent studies have shown that female birds are screaming. This discovery can't help but make people curious: Is the way male and female listening to the sounds different? In addition, among many tropical birds, the male and female partners will make a highly intertwined duet, which sounds like a continuous song in people.

When I hear the birds next time, try not to imagine it as a pleasant melody or simple sentence, but imagine it as a fast -moving, accurate coordinated dance -it may be as rich as human language or music. Emotional and meaning is expressed in different ways.

This article is authorized to reprint from WeChat public account: Global Science Author: Global Science

Reprinted content only represents the author's point of view

It does not represent the high energy office of the Chinese Academy of Sciences

Edit: Meow Meow

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