养狗的人会知道，狗有时候会对着空荡荡的地方（或是空气）无缘无故地汪汪叫。这真的很挑战狗主人的耐心，这个时候，狗狗到底在想什么呢？

常理上来讲，狗是人类最好的朋友。但是当狗对着房间里空荡荡的角落，对着门，或对着任何一个没有动静的地方汪汪叫时，这份友情可能就要面临考验了。

是狗出现幻觉了吗？还是它正在和人类看不见的生命交谈？亦或是狗只是想把主人逼疯？

A dog can be a person’s best friend, or so the theory goes. But that relationship can be tested when a dog begins barking at an empty corner of a room, at a door, or anywhere where there doesn’t appear to be any activity at all taking place. Is the dog hallucinating? Is it communicating with interdimensional beings? Or does it simply want to drive its owner to the brink of sanity?

美国养犬俱乐部称，对于毫无来由的汪汪叫最常见的解释是它可能并不是真的无缘无故，只不过人类无法察觉到狗能感知到的视觉、听觉和嗅觉线索。

According to the American Kennel Club, the most common explanation for unprompted woofing is that it’s not really unprompted at all. Instead, it’s likely that humans are simply unable to perceive whatever visual, aural, or olfactory cues the dog is sensing.

显然，狗具有超级敏锐的听力，能听到更高音调的声音。理论上，狗可能是在对某种声音作出反应，可能是远处车辆的鸣笛声，而人听不见这个声音。

Dogs are, obviously, equipped with superior hearing, including the ability to detect sounds that are higher in pitch. In theory, a dog could be reacting to a noise that a person nearby wouldn’t be able to hear—possibly a far-off vehicle siren.

如果一条狗在夜里似乎无缘无故地叫起来，这可能是因为四周的声音减弱了，让狗可以听到其他狗的叫声。因为狗是有地盘意识的，一只狗汪汪叫会引发很多只狗都开始模仿。

If a dog barks seemingly unprovoked at night, it might be because ambient noise is lessened and they’re more attuned to the various howling and barking of other dogs. Because dogs are territorial, one dog barking can turn into many.

狗在黑暗中比人看得更清楚，这是因为它们的视网膜能吸收更多光线。如果一条狗对着黑暗中一片漆黑的后院汪汪叫，那么可能是它们注意到了某样东西，也许是一只野生动物，一片叶子，或一位连环杀手。

Dogs are also able to see better in the dark than humans thanks to their ability to get more light into their retinas. If a dog is reacting to what looks to you like an empty backyard at night, it’s possible that something has caught their attention, be it a wild animal, a leaf, or a serial killer.

这并不意味着狗汪汪叫都是因为它们察觉到了什么。有些狗可能只是因为无聊，才自发地叫起来，从而引起主人的注意，这就表明它们需要更多运动或玩乐时间。

That’s not to say that dogs only bark when their canine senses are triggered. Some dogs might bark spontaneously out of boredom, in which case more exercise or playtime is probably needed. They might also be trying to get their owner’s attention.

美国养犬俱乐部建议，狗主人尽量不要在狗汪汪叫的时候训斥它们，因为它们只是保持警觉而已。你应该试着去安抚狗，让狗知道你已经了解它的担忧。如果狗总是一边望向窗外一边叫，你可以试着拉上窗帘，让它们看不到窗外的事物。如果你怀疑狗狗是因为听到了某种声音而叫，你可以播放一些白噪音（比如打开电视或收音机）来盖住这种声音。

The AKC recommends that owners avoid scolding their dogs for barking, since they’re simply trying to remain vigilant. Instead, you can try reassuring the dog to let them know you’re aware of their concern. If they tend to bark while gazing out a window, you can also try to manage their vantage point with curtains. If you suspect the source is an audio cue, some white noise, like a television or radio, can help.

尽管不太常见，但长期汪汪叫也可能是狗狗出现认知问题的信号。如果它不停地叫，而灌木丛里又一无所获，你可能要考虑带狗去看看兽医。

Less often, chronic barking might be a sign of cognitive issues. If barking is persistent and no fugitive is hiding out in your bushes, then you might consider a trip to the vet.

审稿：潘一侨、齐磊