Compared to dogs, humans have a fairly narrow range of audible frequencies. We can hear sounds in the approximate range of 64 to 23,000 hertz, while dogs can hear sounds in the approximate range of 67 to 45,000 hertz. This greater range explains why you may notice your dog barking without being able to hear what he's barking at. Dogs frequently pick up ultrasonic frequencies that scare them and cause them to bark or howl.
Any sound that is said to be ultrasonic is outside the audible frequency range for humans. This does not mean that it is inaudible for other animals, and in fact ultrasonic sounds in the range of 20 to 100 kilohertz are frequently used to train bats, dolphins and other species. Some dog owners will train their dogs using whistles that emit an ultrasonic frequency, while some people will attempt to quiet barking dogs using ultrasonic sound devices.
Dogs’ anatomy gives them an advantage over humans when it comes to hearing. They have large external ears, and many breeds are able to adjust the shape and direction of their ears in order to better transmit high frequency sounds to their ear drums. Furthermore, a dog’s cochlea, situated in the inner ear, has 3 1/4 turns in comparison to a human’s 2 1/2, which likely provides room for more sound sensory cells.
Some of the high frequency noises that are audible to dogs and may cause them to bark include dog whistles, anti-barking remotes that neighbors sometimes buy in an attempt to quiet a vocal dog, and even some phone apps designed specifically to emit ultrasonic noise. Dogs also pick up on ultrasonic noise pollution from household items like your TV, dryer and washing machine. Too much noise at a high frequency can stress your dog out and cause her to bark.
The type of barking that dogs typically engage in when they hear an unpleasant sound is alarm barking, which they do because they are concerned about an unfamiliar stimulus. If your dog is barking excessively at external stimuli, you should try to find the source of the noise and eliminate it if possible. If it is not possible, train your dog not to bark by calmly and clearly saying “quiet” whenever he starts, then holding his muzzle until he stops. Then ask him to sit and reward him with a treat. Continue with this reward system over a period of time until he no longer barks excessively.
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