Prairie Dog barks have ______ meanings. What did the researcher use to record Prairie Dog barks?

Lecturer: Welcome to this presentation on Prairie Dogs. You can see a picture of these rather cute animals on this slide. As you can see, they are about the size of a rabbit and they have a brown or clay-coloured coat with black-tipped hairs and a black-tipped tail. The underside of the prairie dog is a light tan colour. They have short legs and sharp claws to help them dig their homes. Their bodies are 12-15 inches long with a 3-4 inch tail and they weigh 2-4 pounds.
    I’ve been interested in these animals for a long time and would like to talk about a remarkable discovery. The barks of prairie dogs have distinct, individual meanings. Prairie dogs have different "words" for tall human in yellow shirt, short human in green shirt, coyote, deer, red-tailed hawk and many other creatures. They can even coin new terms for things they’ve never seen before, independently coming up with the same calls or words, according to research done over two decades by a professor from Arizona University, who can now not only call himself a biology professor, but also a prairie dog linguist.
    Prairie dogs of the Gunnison’s species, which were studied intensely, actually speak different dialects in Arizona and in Colorado, but they would probably understand one another, research indicates. So far, this is believed to be...or prairie dogs appear to be demonstrating, the most sophisticated communication system that anyone has shown in animals. Prairie dog chatter is variously described by observers as a series of yips, high-pitched barks or eeks. And most scientists think prairie dogs simply make Sounds that reflect their inner condition. That means all they’re saying are things like "ouch" or "hungry" or "eek." But we now know that prairie dogs are communicating detailed information to one another about what animals are showing up in their colonies, and maybe even gossiping.
    Linguists have set five criteria that must be met for something to qualify as language: It must contain words with abstract meanings; possess syntax in which the order of words is part of their meaning; have the ability to coin new words; be composed of smaller elements; and use words separated in space and time from what they represent. The American researchers focussed their efforts on these five criteria to see if prairie dogs use a language, as defined by human linguists, or not. Work was done in the field and in a laboratory. With digital recorders, they recorded the calls prairie dogs make as they see different people, dogs and other animals of different sizes and with different coat colours, such as hawks and elk. They then analysed the sounds using a computer that dissects the underlying structure and creates a sonogram, or visual representation of the sound. Computer analysis later identifies the similarities and differences.
    The prairie dogs have calls for various predators but also for elk, deer, antelope and cows. It’s as if they’re trying to inform one another what’s out there. So far, the researchers have recorded at least twenty different "words." Some of those words or calls were created by the prairie dogs when they saw something for the first time. Four prairie dogs in the lab were shown a great-horned owl and European ferret, two animals they had almost certainly not seen before, if only because the owls are mostly nocturnal and this kind of ferret is foreign. The prairie dogs independently came up with the same new calls. In the field, black plywood cut-outs showing the silhouette of a coyote, a skunk and a circular shape were randomly run along a wire through the prairie dog colony. Now, there are no black ovals running around out there and yet they all had the same word for black circle. The researchers believe that prairie dogs are genetically programmed with some vocabulary and the ability to describe things.
    The researchers then played back a recorded prairie dog alarm call for coyote in a prairie dog colony when no coyote was around. The prairie dogs had the same escape response as they did when the predator was really there. In other words, there’s no coyote present, but the prairie dogs hear this recording of prairie dogs barking, "Hey, there’s a coyote!" and they say, "Oh, coyote! Better hide." Computer analysis has been able to break down some prairie dog calls into different components, suggesting the creatures have yet another element of a real language. The researchers are quietly confident that they will establish that the prairie dogs will meet the five criteria set by linguists. Then, there will be conclusive proof that animals have language.