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Human and canine hearing don't cover exactly the same frequency range.
Dogs can detect substantially higher-frequency sounds than humans, which is why certain dog whistles can produce sounds that are difficult or impossible for people to hear while remaining audible to dogs.
Their movable ears can also help gather and locate sound.
A room that seems completely quiet to a person may contain sounds that are perfectly noticeable to a dog.
© Louisiana State University School of Veterinary Medicine