Inside of a Dog: What Dogs See, Smell, and Know

by Alexandra Horowitz

when experimenters analyzed the spectrograms of thousands of dog barks during one of three contexts—a stranger ringing the doorbell, being locked outside, or in play—they found three distinct types of barks. Stranger barks were the lowest in pitch and the harshest: they are nearly spat out. Less variable than the other types, stranger barks are well designed to send a message over a distance, something necessary if caught in a threatening situation alone. They can also be combined into “superbarks,” concatenations of barks that together last much longer than the duration of barking in other contexts. The end result is a bark that most human listeners find to be aggressive. The isolation barks tended to be higher-frequency and more variable: some ranged from loud to soft and back again, some went from high to low. These barks are lobbed into the air one by one, sometimes with great intervals between them. They sound “fearful,” people tend to say. Play barks, too, are high-frequency, but they happen more often one after the other than the isolation barks. They’re directed at someone else, unlike isolation barks: at a dog or human playmate. There is considerable individual variation, of course: not every dog barks alike. The stranger bark of a small dog may come out as rar, rar or raoaw, raoaw, while a larger dog emits a capital-r Rumph.